The CDC Recaps The 2014-15 Flu Season

P&I Mortality the past 5 Flu Seasons – Credit FluView

 

 

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With this year’s flu season essentially over in the Northern Hemisphere, it is time once again for the CDC to assess the damage, and as many already know – it was a tough flu year.   Between having an H3 dominated year, and a `drifted’ H3N2 virus that largely evaded this year’s vaccine, the impact was particularly hard on those over the age of 65.

 

2014-15 will go down as the third moderately severe flu season in a row, which followed two comparatively mild seasons (2010-11 & 2011-12), proving you just never know what the next flu season will bring.

 

Yesterday the CDC released the following post-mortem analysis of this latest influenza epidemic season.

 

 

2014-2015 Flu Season Drawing to a Close

April 27, 2015 – Flu activity continues to decline, according to the most recent FluView, which reports that influenza-like-illness (ILI) in the United States has fallen below baseline for the second consecutive week since the middle of November. Other key indicators are declining as well, signaling that the 2014-15 flu season is drawing to a close. The April 24, 2015 FluView covers influenza activity reported from April 12-April 18, 2015.

During the 2014-2015 season, influenza activity started early and had a relatively long duration. Influenza-like-illness (ILI) went above baseline the week ending November 22 and remained elevated for 20 consecutive weeks, making this season slightly longer than average. For the past 13 seasons, influenza-like-illness has been at or above baseline for 13 weeks on average, with a range of 1 week to 19 weeks. The ILI curve for this season is most similar to that from the 2012-2013 season, which is the season during which ILI activity remained above baseline for 19 weeks.

This season was severe for people 65 and older especially. While hospitalization rates are almost always highest among people 65 and older, this season CDC recorded the highest hospitalization rates among this age group since this type of record-keeping began in 2005. People 65 and older accounted for more than 60 percent of all reported hospitalizations and from September 28 through April 18, an estimated 313.8 per 100,000 people in the age group were hospitalized from flu. The next highest recorded hospitalization rate in this age group (182.3 per 100,000) occurred during the 2012-2013 season.

The extremely high hospitalization rate in older adults elevated the overall hospitalization rate for all age groups in the United States to 63.6 per 100,000 people. Hospitalization rates for other age groups were either similar to or lower than what has been seen previously. For example, the age group normally next-most affected by severe illness resulting in hospitalization is children 0-4 years of age. While children in that age group did have the second-highest hospitalization rate this season, that rate through the week ending April 18 (55.4 per 100,000) is lower than what was seen during the same week in 2012-2013 (65.9 per 100,000).

During most of the season influenza A (H3N2) viruses predominated however the country experienced a second wave of influenza B flu activity since early March. Second waves of influenza B activity are common. Seasons during which influenza A (H3N2) viruses predominate typically have higher rates of hospitalizations and more deaths, particularly among older people and children. The last season when H3N2 viruses predominated was in 2012-2013.

Flu-related deaths this season were within expected boundaries for an H3N2 dominant season. CDC monitors flu-related deaths through the 122 Cities Mortality Reporting System, which reports the total number of death certificates processed and the number of those for which pneumonia or influenza is listed as the underlying or contributing cause of death in 122 U.S. cities. Pneumonia and influenza diagnoses (P&I) first rose above the epidemic threshold the week ending January 3, 2015 and peaked the week ending January 17, 2015 at 9.3%. This is comparable to recorded percentages for past severe seasons, including the 2003-04 season when P&I reached 10.4% and the 2012-13 flu season when P&I peaked at 9.9%.

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Our eyes now turn to the Southern Hemisphere, where the newly formulated flu vaccine is hoped will make a bigger dent in H3N2’s impact this year. But we never really know whether the Southern Hemisphere will be a continuation of our outgoing flu season, or prove to be a harbinger of changes we might see here come the fall.

HK’s Imported H7N9 Case Dies, Seasonal Flu Continues Strong

 

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As the City of Hong Kong struggles with a particularly severe H3N2 flu season, its 3rd imported H7N9 case of the winter (and 13th overall) has reportedly died in a local hospital a week after his case was announced.  Of the two other H7N9 cases imported into Hong Kong this season, one has recovered while the other remains hospitalized in critical condition.

H7N9 bird flu infected man dead

Sing Tao Daily 

Had earlier to the mainland, after his return confirmed cases of H7N9 avian influenza in 61-year-old man, extended to 6:30 am dead. Food and Health Secretary Ko Wing-man, said most H7N9 cases in Hong Kong imported from mainland China appealed to the public when the areas affected by avian influenza to be alert.

Last month, the patient twice to Zhangmutou, and go to the market to buy two chickens have been slaughtered, after returning discomfort, admitted to Queen Mary Hospital intensive care unit, extended to 6:35 this morning, where he died.

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Of the 602 H7N9 known cases reported by the World Health Organization as of February 23rd, 227 deaths have been reported, yielding an impressive 37% fatality rate.  

But the real CFR (case fatality rate) is likely far lower, as only the `sickest of the sick’ are likely to be hospitalized, tested, and identified as carrying the virus.  And those people who are sick enough to be hospitalized are also more likely to succumb.

 

If we could factor in the mild or moderate cases that never get counted, but recover on their own, that sky-high CFR would probably drop precipitously. 

 

But even a 10-fold drop in mortality would leave us with a very daunting flu, comparable to the 1918 pandemic.

 

Meanwhile, Hong Kong’s seasonal flu continues unabated, and their Centre for Health Protection has published a YTD report showing its impact.  

 

Thus far, seasonal flu has claimed at least 307 lives in Hong Kong this winter.  To put that in perspective, last year 133 deaths were reported – and this year’s flu season is far from over.

 

Update on severe seasonal influenza cases (As of 1 March, 2015, 12 noon)

H7N9 In Guangdong, Seasonal Flu In Hong Kong

Credit HK CHP

 

 

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Hong Kong’s CHP has been notified of an additional H7N9 in Guangdong Province, bringing to 54 the number of cases reported from their neighboring province this winter.  Unfortunately, timely reports from the rest of mainland China are in short supply, making it difficult to characterize this year’s outbreak.

17 February 2015

CHP notified of additional human case of avian influenza A(H7N9) in Guangdong 

The Centre for Health Protection (CHP) of the Department of Health (DH) is today (February 17) closely monitoring an additional human case of avian influenza A(H7N9) notified by the Health and Family Planning Commission of Guangdong Province (GDHFPC), and again urged the public to maintain strict personal, food and environmental hygiene both locally and during travel.

According to the GDHFPC, the female patient aged 33 in Guangzhou was hospitalised for treatment in critical condition.

To date, 574 human cases of avian influenza A(H7N9) have been reported by the Mainland health authorities, respectively in Guangdong (163 cases), Zhejiang (156 cases), Jiangsu (70 cases), Fujian (58 cases), Shanghai (45 cases), Hunan (24 cases), Anhui (17 cases), Xinjiang (10 cases), Jiangxi (nine cases), Shandong (six cases), Beijing (five cases), Henan (four cases), Guangxi (three cases), Jilin (two cases), Guizhou (one case) and Hebei (one case).

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Meanwhile, Hong Kong’s severe flu season continues unabated with daily reports painting a grim picture of both the number of ICU admissions and deaths, with the number of fatal flu cases this winter on track to more than double last year’s total.

 

 

Latest update of surveillance data in winter influenza season

The Centre for Health Protection (CHP) of the Department of Health today (February 17) reported the latest surveillance data of the winter influenza season, and again urged the public to heighten vigilance and get vaccinated early against seasonal influenza.

Regarding severe cases, from noon yesterday (February 16) to noon today, 22 additional cases of influenza-associated admission to intensive care units or death (including 18 deaths) among adults aged 18 or above have been recorded under the enhanced surveillance in collaboration with public and private hospitals reactivated since January 2, bringing the total to 322 (228 deaths) so far. Among them, 306 were A(H3N2), 10 were A pending subtype and six were B. In the last winter season in early 2014, 266 (133 deaths) were filed.

Meanwhile, no additional cases of severe paediatric influenza-associated complication or death among children aged under 18 have been reported since yesterday via the ongoing reporting system and the total this year hence remains at 14 (no deaths) and all were A(H3N2). In 2014, 27 (four deaths) were filed.

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This year’s flu season is so grim - that while located in the Northern Hemisphere - Hong Kong is making arrangements to purchase a quantity of the recently revised Southern Hemisphere vaccine, as announced earlier this month in New flu vaccine ready by April.

As we’ve seen this year in North America, Hong Kong’s flu season has been dominated by a drifted H3N2 virus which has greatly reduced this year’s vaccine effectiveness, and its greatest impact has been on the elderly.

 

HK’s Dr. Ko Wing-man On Flu Reassortment Concerns

Reassortment is the mechanism where two different flu viruses infect the same cell simultaneously, and swap genetic material, producing a new, hybrid virus. -  Credit AFD

 

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At the same time that mainland China is experiencing their third winter wave of H7N9 infections, Hong Kong and the rest of southern China are embroiled in a particularly nasty H3N2 seasonal flu epidemic. 

 

Today’s flu update from Hong Kong’s CHP acknowledges:

 

Regarding severe cases, from noon yesterday (February 7) to noon today, four additional cases of influenza-associated admission to intensive care units or death (including two deaths) among adults aged 18 or above have been recorded under the enhanced surveillance in collaboration with public and private hospitals reactivated since January 2.

This brings the total number to 218 ( 142 deaths) so far. Among them, 207 were A(H3N2), five were B and six were A pending subtype. In the last winter season in early 2014, 266 (133 deaths) were filed.

Meanwhile, no additional cases of severe paediatric influenza-associated complication or death among children aged under 18 have been reported since yesterday via the ongoing reporting system. The total this year hence remains at 11 (no deaths) and all were A(H3N2). In 2014, 27 (four deaths) were filed.

 

Things are so bad - that while located in the Northern Hemisphere - Hong Kong is making arrangements to purchase a quantity of the recently revised Southern Hemisphere vaccine, as announced yesterday in New flu vaccine ready by April.

A couple of weeks ago, in Hong Kong CHP Update On Imported H7N9 Case, we looked at published reports saying that HK CHP director Dr. Ko Wing-man had publically expressed concerns over the possibility that this year’s seasonal flu, and the H7N9 virus, could cross paths and create a new, reassorted virus.

 

Today, based on reports in the South China Morning Post and Sputniknews, Dr. Ko Wing-man has apparently once again voiced those concerns.

 

Hong Kong Health Minister Warns of Possible New Deadly Virus Outbreak

© AFP 2015/ ISAAC LAWRENCE

 16:18 08.02.2015 (updated 16:54 08.02.2015)

Hong Kong's health minister stated that rampant seasonal flu in Hong Kong and the recent strain of bird flu detected in poultry could together give rise to a deadly new virus.

MOSCOW, (Sputnik) – The rampant seasonal flu in Hong Kong and the recent strain of bird flu detected in poultry could together give rise to a deadly new virus, Hong Kong's health minister said Sunday.

“If a person contracts two viruses, a gene recombination is likely to happen,” Ko Wing-man was quoted as saying by the South China Morning Post, adding that the mutation could lead to a more contagious virus.

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A novel/seasonal flu reassortment is not a new concern, nor is this scenario limited to H7N9, or the H3N2 virus. Anytime two different flu viruses inhabit the same host (human, avian, porcine, etc.) at the same time, the potential for seeing a reassortant virus exists. 

Most of the time, however, the resultant hybrid virus fails to thrive and spread, and it is never even noticed.

But when you have an abundance of seasonal flu co-circulating with a novel flu virus like H7N9, the odds of seeing a someone infected with both subtypes – admittedly a rare event – go up.  And the more opportunities these viruses have to get together, the better the chances are they will produce an offspring.

 

Last month, in EID Journal: Timing of Influenza A(H5N1) in Poultry and Humans Worldwide, 2004–2013, we looked exactly these concerns, albeit focusing on H5N1 and seasonal flu interactions.   The author’s wrote:

Abstract

Co-circulation of influenza A(H5N1) and seasonal influenza viruses among humans and animals could lead to co-infections, reassortment, and emergence of novel viruses with pandemic potential.

 

Previously, in the Lancet: Coinfection With H7N9 & H3N2, we saw the first evidence of co-infection with the newly emerged H7N9 virus and a seasonal flu virus in a human. While last October, in EID Journal: Human Co-Infection with Avian and Seasonal Influenza Viruses, China, we looked at co-infections in 2 patients in Hangzhou, in January 2014.

 

In all of three of these cases, no reassortant virus was detected.

But In 2011,  an influenza co-infection in Canada led to the creation of a unique hybrid reassorted virus (see Webinar: pH1N1 – H3N2 A Novel Influenza Reassortment), although it was not passed on to anyone else.

 

And in 2010, in EID Journal: Co-Infection By Influenza Strains, I wrote about a study in New Zealand during the opening months of the 2009 pandemic that discovered at least 11 co-infections (out of 1,044 samples tested) with the older seasonal H1N1 virus and the newly emergent pandemic H1N1 virus.

While rarely detected, influenza A coinfections are probably more common than we realize.  Luckily, most do not result in the production of a hybrid strain, else we’d be hip deep in novel viruses all the time.

 

Over the past few years we’ve seen a growing list of novel (avian, swine, canine) flu viruses emerge (H5N3, H5N2, H5N5, H5N6, H5N8, H7N9, H10N8, H3N8, H6N1, H1N1v, H1N2v, H3N2v, etc. . .), and each carries some risk of reassortment. 

With other novels viruses, or with human viruses. Or conceivably both.

 

How big that risk really is, in terms of producing a pandemic virus, is unknown.  Most of these reassortant hybrids will fail and fade away unnoticed, either being biologically `flawed’ in some way, or simply not as competitive as existing strains.

 

The odds of any one viral assignation producing a viable, humanized virus is probably fairly remote.

The concern is, if these viruses get enough rolls of the genetic dice, they will eventually roll a natural.  Which is why we watch Hong Kong, mainland China, and Egypt so carefully this time of year.

EID Journal: Timing of Influenza A(H5N1) in Poultry and Humans Worldwide, 2004–2013

Figure 3. Monthly average number of highly pathogenic avian influenza A(H5N1) infection outbreaks among poultry (black line) and human H5N1 cases (white bars) for 8 study countries (Bangladesh, Cambodia, China, Egypt, Indonesia, Thailand, Turkey, and Vietnam) that reported 90% of all poultry H5N1 outbreaks and 97% of all human H5N1 cases during 2004–2013.

 

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While it will come as no surprise that they found the incidence of H5N1 infection – both in poultry and people – peaks during the months of January–March, there’s more to the synopsis which appeared yesterday in the CDC’s EID Journal on H5N1 activity over the past decade.

First, a link and the abstract, along with a few snippets from the discussion section (bolding mine) of this detailed, well-timed report, then I’ll return with more.

 

Volume 21, Number 2—February 2015

Synopsis

Timing of Influenza A(H5N1) in Poultry and Humans and Seasonal Influenza Activity Worldwide, 2004–2013

Lizette O. Durand, Patrick Glew, Diane Gross, Matthew Kasper, Susan Trock, Inkyu K. Kim, Joseph S. Bresee, Ruben Donis, Timothy M. Uyeki, Marc-Alain Widdowson, and Eduardo Azziz-Baumgartner

 Abstract

Co-circulation of influenza A(H5N1) and seasonal influenza viruses among humans and animals could lead to co-infections, reassortment, and emergence of novel viruses with pandemic potential.

We assessed the timing of subtype H5N1 outbreaks among poultry, human H5N1 cases, and human seasonal influenza in 8 countries that reported 97% of all human H5N1 cases and 90% of all poultry H5N1 outbreaks. In these countries, most outbreaks among poultry (7,001/11,331, 62%) and half of human cases (313/625, 50%) occurred during January–March.

Human H5N1 cases occurred in 167 (45%) of 372 months during which outbreaks among poultry occurred, compared with 59 (10%) of 574 months that had no outbreaks among poultry. Human H5N1 cases also occurred in 59 (22%) of 267 months during seasonal influenza periods. To reduce risk for co-infection, surveillance and control of H5N1 should be enhanced during January–March, when H5N1 outbreaks typically occur and overlap with seasonal influenza virus circulation.

<SNIP>

Discussion

Our study reaffirms that, in Southeast Asia, H5N1 outbreaks among poultry and human H5N1 cases often occur seasonally, during months when temperatures are relatively cool. Even when accounting for H5N1-endemic countries outside Southeast Asia, most (>50%) poultry H5N1 outbreaks and human H5N1 cases of H5N1 infection occurred during January–March.

Our analysis of 2004–2013 data from 8 countries also suggests that lower ambient temperatures are associated with H5N1 outbreaks among poultry, even though half of our data came from tropical countries, where annual temperature variations are often small. These results are similar to those described by Park and Glass, who observed poultry H5N1 outbreaks during 1997–2006 in Southeast Asia and China and concluded that these outbreaks most often occurred during colder months (10). Other studies have found similar associations (5,25,26). A decrease in temperature can make poultry more susceptible to H5N1 because lower ambient temperature can decrease poultry immunity (27–29). Moreover, cold weather may enable prolonged viral survival in the secretions and feces of infected poultry, and anticipation of seasonal holidays (e.g., Chinese New Year) often results in increases in population density of domestic poultry and in trafficking of poultry (27–34).

Human H5N1 cases were almost 5 times more common in months during which poultry H5N1 outbreaks occurred. These findings reaffirm reports that human H5N1 virus infection is typically preceded by exposure to sick or dead poultry (35) and suggest that human and animal health officials in affected countries should explore the effectiveness of education and outreach efforts before and postexposure prophylaxis during anticipated H5N1 epidemic periods. 

Our data also suggest that one fifth of human H5N1 cases occurred in months during which seasonal influenza was epidemic. Concurrent H5N1 and human seasonal influenza activity provides opportunities for humans and other animals (e.g., swine) to become co-infected with these co-circulating viruses and for the viruses to reassort. Reassortment may generate novel influenza A virus strains with the ability to cause sustained human-to-human transmission.

(Continue . . . .)

The final paragraph excerpted above discusses the dangers of having H5N1 co-infecting humans (or other hosts) with an already humanized seasonal flu virus (i.e. H3N2, H1N1). 

 

Reassortment is the mechanism where two different flu viruses infect the same cell simultaneously, and swap genetic material, producing a new, hybrid virus. -  Credit AFD

 

We know this can happen in the wild, as reassortment in birds and/or swine is the route by which many new subtypes of influenza are created.  It is how the H5N1 virus originally evolved in the 1990s, and how H7N9 abruptly appeared in the spring of 2013. 

 

Over the past year we’ve seen several additional reassortants of concern: including H5N6, H5N8, and H5N3, H10N8, and based on reports from Taiwan this week, a new H5N2.

 

We’ve also seen this process (albeit, rarely) in humans. In 2011 an influenza co-infection in Canada led to the creation of a unique hybrid reassorted virus (see Webinar: pH1N1 – H3N2 A Novel Influenza Reassortment), although it was not passed on to anyone else.

 

Influenza co-infections in humans are rarely documented, but probably occur more frequently than we suppose.  Luckily, the creation of successful reassortant viruses is the exception, not the rule.

 

In the summer of 2013, in the Lancet: Coinfection With H7N9 & H3N2, we saw the first evidence of co-infection with the newly emerged H7N9 virus and a seasonal flu virus in a human. While last October, in EID Journal: Human Co-Infection with Avian and Seasonal Influenza Viruses, China, we looked at co-infections in 2 patients in Hangzhou, in January 2014. In these cases, no reassortant virus was detected.

 

While an influenza co-infection leading to the creation of a biologically `fit’, and competitive, novel virus is the viral equivalent of hitting the lottery, when you have a growing number of viral players (H5N1, H7N9, H5N6, H5N8 . . .),  buying huge numbers of tickets (infecting hosts) every week, the chances of hitting the `right’ genetic combination go from being astronomically bad to being reasonably good over the long run.

Which is why we watch H5N1, H7N9, and the bevy of newly emerged avian viruses carefully for any signs that they are playing too well with others.

When Influenza Goes Rogue

Variability of Flu Seasons - Mash up from Multiple FluView Reports

 

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Most people are aware that over the past century we’ve seen 4 influenza pandemics; the 1918 Spanish Flu, the 1957 Asian Flu, 1968 Hong Kong Flu & the 2009 H1N1 pandemic. Of these, the 1918 pandemic was (by far) the worst, but each of the others exacted a heavy toll as well.

Less well known have been the `rogue’ flu years, when we saw something less than a pandemic, but something substantially worse than a typical flu season.

 

There is, of course, a good deal of variance between `normal’ flu seasons (see chart above), with significant jumps in P&I (Pneumonia & Influenza) mortality registered in the years 2000,  2003 and 2013, while 2012 was the mildest year for influenza in decades.

 

As a paramedic, I worked the `pseudo-pandemic’ of 1977, and I can attest that it had a big impact, even if it didn’t rise to the level of a global pandemic.  In that case, an old nemesis – H1N1 – which had disappeared 20 years earlier after the arrival of H2N2 in the 1957 pandemic, came back.

 

While the exact mechanism of that virus’ return isn’t known, the strain was so similar to one last seen in the 1950s that it has been postulated that it was the result of an accidental lab release in China or Russia (see PLoS ONe The Re-Emergence of H1N1 Influenza Virus in 1977 . . . ).  Hence, it was dubbed the `Russian Flu’.

Those over the age of 20 (I made the cut by 3 years), carried some immunity to the old H1N1 virus, but children and adolescents born after 1957 did not, and so they were the most susceptible to infection.  Emergency rooms were slammed, and while the impact was limited and most patients recovered, in some people’s books 1977 qualifies as a `pseudo-pandemic’ year . . . at least for kids.

H1N1’s impact went far beyond just what happened in 1977, for for the first time in our limited knowledge of influenza strains, we ended up having two seasonal influenza A strains in co-circulation; H3N2 and H1N1. Something that previously, had never been observed.

Another, less well remembered event, was the `Liverpool Flu’ of 1951, which for awhile, killed at a greater rate than did the Great Influenza of 1918.

 

For most of the world, 1951 was an average flu year.  The dominant strain of influenza that year was the so-called `Scandinavian strain', which produced mild illness in most of its victims. In fact, if you look at a graph of flu activity for the United States, running from 1945 to 1956, you'll see nary a blip.

 

But in December of 1950 a new strain of virulent influenza appeared in Liverpool, England, and by the end of the flu season, had spread across much of England, Wales, and Canada. This from an absolutely fascinating EID Journal article: Viboud C, Tam T, Fleming D, Miller MA, Simonsen L. 1951 influenza epidemic, England and Wales, Canada, and the United States.

 

The 1951 influenza epidemic (A/H1N1) caused an unusually high death toll in England; in particular, weekly deaths in Liverpool even surpassed those of the 1918 pandemic. . . . . Why this epidemic was so severe in some areas but not others remains unknown and highlights major gaps in our understanding of interpandemic influenza.

 

According to this study, the effects on the city of origin, Liverpool, were horrendous.

 

In Liverpool, where the epidemic was said to originate, it was "the cause of the highest weekly death toll, apart from aerial bombardment, in the city's vital statistics records, since the great cholera epidemic of 1849" (5). This weekly death toll even surpassed that of the 1918 influenza pandemic (Figure 1)

 

This extraordinary graph shows the excess deaths in Liverpool during this outbreak (red line),  while the black line shows the peak deaths during the 1918 pandemic.  This chart shows excess deaths by   A) respiratory causes (pneumonia, influenza and bronchitis) and B) all causes.

 

For roughly 5 weeks Liverpool saw an incredible spike in deaths due to this new influenza.   And it didn’t remain localized.  While it appears not to have spread as easily as the dominant Scandinavian strain, it managed to infect large areas of England, Wales, and Canada over the ensuing months.

 

Getting started relatively late in the flu season, this new strain never managed to spread much beyond UK and Eastern Canada.  Nor did it reappear the next flu season.  It vanished as mysteriously as it appeared.

 

Another example, but one that affected the transmissibility and not the virulence of the seasonal virus, occurred in 1947.  The so-called `vaccine failure’ year, when a new H1N1 virus swept quickly around the world.

 

In 1947 a new variant of the H1N1 virus appeared on military bases – first noticed in Japan – and quickly spread from there. While it produced a generally mild illness there were apparently low levels of immunity in the population (see EID Journal Influenza Pandemics of the 20th Century).  1947 is little remembered today, except by epidemiologists, because while widespread, this new flu strain produced few excess deaths.

.

And then there were the epidemics that might have been – but that for reasons unknown – didn’t happen.

 

In early 1976, after an absence of nearly two decades, a never-before-seen strain of H1N1 swine flu appeared at Ft. Dix, New Jersey – prompting a national emergency response for its expected return in the fall.  While that failed to happen (see Deja Flu, All Over Again), the following year we were blindsided by the `Russian’ H1N1 flu described above.

Why the 1976 H1N1 Swine flu fizzled out remains a mystery.

 

As we go into each year’s flu season, we are always presented with a  `Forrest Gump’ moment. We never quite know what we are going to get.

 

But we do know that even in a non-pandemic year, we can see tens of thousands of American lives lost due to influenza. Globally, we are talking hundreds of thousands. And that a season can start off mild and unassuming (like 1950) and end up as a raging epidemic. 

 

We also know that a flu season can affect different parts of the world differently.  We may very well see an H3N2-centric flu season this year in North America, but in Europe or Asia, they could easily see H1N1 instead.

 

While every year is a question mark, this year we have a number of additional variables at play. The first comes from the rise in the number of antigenically diverse H3N2 clades being reported around the world (see ECDC: Influenza Characterization – Sept 2014). 

 

Since this fall’s vaccine strains were selected last February, the `balance of power’ among flu H3N2 flu strains has begun to shift, and the H3N2 component for next year’s Southern Hemisphere flu shot has already been changed to meet the challenge of an emerging A/Switzerland/9715293/2013 (H3N2)-like virus. 

Complicating matters, last week it was announced that last year’s LAIV (Live Attenuated Influenza Vaccine)  –  aka FluMist nasal spray vaccine – was not effective against the H1N1(pdm) virus in children aged 2-8, and that it is likely to be ineffective this year as well.

 

And if all of this isn’t enough uncertainty, this year we are watching more novel flu strains than ever before;  H7N9, H5N1, H5N6, H5N2, H5N8, H5N3, H9N2 and H10N8 just to mention the biggest concerns.  You’ll find an excellent overview of these emerging avian flu threats in this weeks’ FAO-EMPRES Report On The Emergence And Threat Of H5N6.

 

As I’ve written here often , flu vaccines are considered very safe – and most years provide a moderate level of protection against influenza. While there are some questions regarding this year’s vaccine `match’ with circulating strains, some protection beats no protection any day of the week.

 

While the vaccine can’t promise 100% protection, it – along with practicing good flu hygiene (washing hands, covering coughs, & staying home if sick) – remains your best strategy for avoiding the flu (and other viruses) this winter.

 

Meanwhile, we have what is shaping up to be a fascinating year for studying all types of flu viruses. 

I Got It From Carol

 

 

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My annual flu shot, that is.      

 

One of the reasons I’m a little late posting this morning is that I had some errands to run, and on the way popped into my local pharmacy to get the flu  vaccine.  Carol is my friendly local CVS pharmacist, and she gives a damn fine shot.

 

I know what you are thinking: It’s only August . . .flu season is still a couple of months away . . . .

 

True, but flu viruses circulate year-round, not just during `flu season’ and flu cases can start to ramp up as early as September.  Since it takes a couple of weeks for flu shot to reach maximum effectiveness, I always try to get the flu shot earlier rather than later.  

 

Here was what the CDC has to say about the timing of getting flu shots.

 

Should I wait to get vaccinated so that my immunity lasts through the end of the season?

CDC and the Advisory Committee on Immunization Practices (ACIP) recommend that flu vaccinations begin soon after vaccine becomes available, ideally by October. However, as long as flu viruses are circulating, it is not too late to get vaccinated, even in January or later. While seasonal flu outbreaks can occur as early as October, flu activity most often peaks in January or later. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against flu virus infection, it is best that people get vaccinated in time to be protected before flu viruses begin spreading in their community. Although immunity obtained from flu vaccination can vary by person, previously published studies suggest that immunity lasts through a full flu season for most people.

There is some evidence, however, that immunity may decline more quickly in older people. For older adults, another flu vaccine option is available called the “high-dose” vaccine, which is designed specifically for people 65 and older. This vaccine contains a higher dose of antigen (the part of the vaccine that prompts the body to make antibody), which is intended to create a stronger immune response in this age group. For more information, see Fluzone High-Dose Seasonal Influenza Vaccine Questions and Answers.

 

I also get the flu vaccine early each year, because if I’m going to promote the practice, I’d darn well better be willing to be first in line to get the shot.  Here are the CDC’s recommendations for who should get the shot each year.

Everyone who is at least 6 months of age should get a flu vaccine this season. This recommendation has been in place since February 24, 2010 when CDC’s Advisory Committee on Immunization Practices (ACIP) voted for “universal” flu vaccination in the United States to expand protection against the flu to more people.

While everyone should get a flu vaccine this season, it’s especially important for some people to get vaccinated.

Those people include the following:

• People who are at high risk of developing serious complications (like pneumonia) if they get sick with the flu.
  • People who have certain medical conditions including asthma, diabetes, and chronic lung disease.
  • Pregnant women.
  • People younger than 5 years (and especially those younger than 2), and people 65 years and older.
  • A complete list is available at People Who Are at High Risk of Developing Flu-Related Complications.
• People who live with or care for others who are at high risk of developing serious complications (see list above).
  • Household contacts and caregivers of people with certain medical conditions including asthma, diabetes, and chronic lung disease.
  • Household contacts and caregivers of infants younger than 6 months old.
  • Health care personnel.

More information is available at Who Should Get Vaccinated Against Influenza.

 

Even though I get the jab every year, I do recognize its limitations.

 

As we’ve discussed before, flu vaccines – while considered very safe – most years only offer a moderate level of protection against influenza, that their VE (vaccine effectiveness) can vary widely between flu shot recipients, and is often substantially reduced among those older than 65 or with immune problems.

 

As an example, in October of 2011, in CIDRAP: A Comprehensive Flu Vaccine Effectiveness Meta-Analysis, we saw a major review indicating the TIV (Trivalent Influenza Vaccine) - during 8 of 12 flu seasons (67%) – produced a combined efficacy of only 59% among healthy adults (aged 18–65 years).

 

They found the protective effects of the flu vaccine could vary considerably from one season to the next, as well as among different age groups (see Study: Flu Vaccines And The Elderly).

 

Still, given their safety record, and relative low cost, I consider them to be good insurance against what can sometimes be a serious illness – particularly as I’m getting older.  As an added incentive, we recently saw a study - that while far from conclusive - suggesting that the Flu Vaccine May Reduce Heart Attack Risk.

 

There is no doubt that we need better flu vaccines – particularly for those at greatest risk from influenza infection; the elderly and those with chronic illnesses (see CIDRAP: The Need For `Game Changing’ Flu Vaccines). But until they can be developed, the vaccines we have can and do help reduce the spread of the virus.

 

While you might not have thought about it, getting your seasonal flu shot each year should be part of your overall preparedness plan. During a disaster or prolonged emergency you are likely to be tired, stressed, and your immune systems could be weakened.

 

The last thing you need during a crisis is to be sick with the flu on top of it.

 

All things considered, getting a flu shot every year makes a lot of sense.  For more, you may wish to revisit:

 

CDC: Flu Shots Reduce Hospitalizations In The Elderly

Research: Low Vaccination Rates Among 2013-2014 ICU Flu Admissions

Two Studies On The 2009 Pandemic Flu Vaccine & Pregnancy

ECDC: 2013-14 Seasonal Influenza Risk Assessment

ECDC Weekly Infographic On Influenza

 

# 8346

 

Each year, usually in late February, the ECDC releases an updated Risk Assessment on their current influenza season, comparing it to previous years, and to reports coming from other regions around the world. 

 

Compared to North America, Europe’s flu season got off to a later start and hasn’t been anywhere near as A(H1)pdm09-dominated (or as severe) as what we’ve experienced on this side of the pond this year. 

From the Report:

In contrast to the season in the US with an overwhelming dominance of A(H1)pdm09 virus and substantial numbers of severe cases, A(H1)pdm09 virus is not as dominant in EU/EEA countries, possibly due to differences in prior exposure to A(H1)pdm09 virus or higher vaccination coverage among the age groups most likely to transmit the disease. In countries not yet affected, the pressure on primary and secondary care services is likely to be less intense than in the US.  

 

This year’s report (13-page PDF file) was posted today on the ECDC website. You’ll find their summary below, along with links to the report.

 

 

Seasonal influenza in Europe: ECDC risk assessment for the 2013-2014 season

04 Mar 2014

​Active circulation of influenza has started late in Europe in the 2013-2014 season, with a different timing across EU/EEA countries, states the annual ECDC risk assessment on seasonal influenza. The first countries affected have been Bulgaria, Greece, Portugal and Spain, where the A(H1)pdm09 influenza virus has dominated. Without any specific geographic pattern, influenza activity has since spread rapidly across Europe. In Bulgaria, Portugal and Spain, the season peaked in weeks 4 and 5/2014, while influenza activity still continues to increase in Greece.

Circulating virus types

In week 07/2014, circulating A(H1)pdm09 virus was dominant or co-dominant in 21 reporting countries while A(H3) was dominant in four countries. In contrast to the season in the US with an overwhelming dominance of A(H1)pdm09 virus and substantial numbers of severe cases, A(H1)pdm09 virus is not as dominant in EU/EEA countries. This may be due to differences in prior exposure to A(H1)pdm09 virus or higher vaccination coverage among the age groups most likely to transmit the disease.

Vaccine effectiveness

Data on viruses circulating so far indicate a good match with the current influenza vaccine. North American studies estimate high to moderate vaccine effectiveness, while a mid-season study from one Spanish region, Navarre, suggests lower effectiveness. This warrants further studies to understand the discrepancies. Vaccination of high-risk groups and healthcare workers, in accordance with national guidelines, in countries that are still at an early stage in their influenza season remains the most effective way of reducing serious outcomes and transmission of the disease.

 

Risk assessment for the remaining season

• In countries with A(H1)pdm09 circulating, especially in countries where influenza activity has already peaked, a later circulation of A(H3) virus is possible. In the event of A(H3) virus circulation, some severe cases are likely, most probably in people older than those typically infected by A(H1)pdm09 virus.
• In countries currently with no/low influenza activity, the dominant influenza virus strain and the intensity are unpredictable, but are likely to be similar to that observed in countries that have already passed their intensity peak (Bulgaria, Portugal and Spain). However, differences in vaccination coverage and natural immunity may influence both intensity and the number of severe cases.
• In the few countries where A(H3) virus has been dominant so far, a second wave or a co-circulation of A(H1)pdm09 virus is possible.

Read full report: Seasonal influenza 2013-2014 in EU/EEA countries

More on seasonal influenza

Weekly infographic on Influenza in Europe 

Spot Shortages Of Tamiflu Reported In Some Regions

Photo Credit – Wikipedia

 

# 8109

 

With the 2013-14 influenza season now well underway, and concerns over the severity of the H1N1 virus – particularly in younger patients and those with co-morbidities – the CDC is urging doctors to consider the early use of antivirals in high risk patients with suspected or confirmed influenza (see CDC HAN Advisory On Early pH1N1 Influenza Activity).

 

While there does not seem to be a national shortage of oseltamivir (Tamiflu ®) – the most commonly prescribed antiviral for influenza – in a few regions (mainly in the South) that have already been hit hard by the flu, some pharmacies are reporting trouble keeping the drug in stock.

 

A couple of  reports on these shortages, after which I’ll be back with a little more on Tamiflu, and this year’s H1N1 flu.

 

Shortage in flu medication worries pharmacists

LITTLE ROCK, Ark. (KTHV) - "We can't find the regular adult dose anywhere right now," Dr. Ray Turnage explained.

Turnage is one of many pharmacists dealing with a shortage of Tamiflu. He said, "There's only one manufacturer for that drug and nationwide all the wholesalers are saying it's a manufacture delay."

Tamiflu is the only medication on the market used to treat the flu and with a shortage in the drug, it could create problems for patients needing it. "Probably the demand is exceeding their supply. So that's the problem is we can't even get adult doses right now," Turnage continued.

Although there have been very minimal cases of the flu this year in Little Rock, with 3 to 4 months left in the flu season, that could change pretty quickly. If it does, Tamiflu in stock could disappear. Turnage said, "That's part of the situation is a few families can, if they can find it, can take all that the pharmacy may have."

(Continue . . .)

 

Shortage reports on Tamiflu in Atlanta, local pharmacies stocked – WSOC-TV

 

The bottom line is, that if you are prescribed Tamiflu, you may have to call around to more than one pharmacy to locate the drug.

While Tamiflu continues to get a strong recommendation from the CDC (see CDC Research On Benefits Of Antivirals For Uncomplicated Influenza), you’ll find no shortage of critics of the drug.  Due in large part to a prolonged reluctance on the part of Roche laboratories to release all of their clinical trial data, and a not totally undeserved reputation of `Big Pharma’ to massage test results. 

 

This has resulted in a vociferous backlash against the government stockpiling of Tamiflu in some quarters (see Dr. Ben Goldacre Opinion Piece). 

 

While academics and activists tend to have a dim view of Roche and their antiviral drug, clinicians obviously see value in oseltamivir,  and continue to prescribe it.  The CDC continues to recommend its use – particularly for high-risk influenza patients - or for the treatment of novel flu (see 2012 blog The CDC Responds To The Cochrane Group’s Tamiflu Study).

 

Although this year’s flu season is being billed in the media as `The Return of Swine Flu’, in truth, the H1N1 virus never departed.  But it has been dominated in North America by the H3N2 virus for the past couple of years.   The following snapshot of last year’s moderately severe flu season comes from last summer’s  MMWR Influenza Activity — United States, 2012–13 Season and Composition of the 2013–14 Influenza Vaccine.

 

Among the seasonal influenza A viruses, 34,922 (68%) were subtyped; 33,423 (96%) were influenza A (H3N2) viruses, and 1,497 (4%) were pH1N1 viruses. In addition, two variant influenza A (H3N2v) viruses were identified.

 

The season before that (2011-12) was the mildest flu season in decades (see 2011-2012 Flu Season Draws to a Close), that while H3N2 dominated, neither strain had a huge impact.

 

The truth is, flu seasons can vary greatly in impact from year-to-year,and with two influenza A strains in global circulation, we usually see one strain or the other dominate (although what strain is dominant in North America my differ from what is dominant in Europe, or Asia the same year).  Often we see 2 or 3 years with one strain in control, and then – as community immunity levels wane – the other takes hold.

 

The CDC’s most recent attempt to estimate the number of deaths associated with flu in the United States finds:

 

An August 27, 2010 MMWR report entitled “Thompson MG et al. Updated Estimates of Mortality Associated with Seasonal Influenza through the 2006-2007 Influenza Season. MMWR 2010; 59(33): 1057-1062.," provides updated estimates of the range of flu-associated deaths that occurred in the United States during the three decades prior to 2007. CDC estimates that from the 1976-1977 season to the 2006-2007 flu season, flu-associated deaths ranged from a low of about 3,000 to a high of about 49,000 people.

 

As much as a 16-fold difference in the number of estimated deaths between a mild flu season, and a heavy one. 

 

Thus far, its been H1N1’s year to roar, and since that strain often impacts those under the age of 65, it tends to get more publicity. The flu death of a young adult from influenza is more unexpected, and has more societal impact, than that of an octagenarian.  And this year, sadly, we are seeing a fair number of such reports (see Texas DSHS Statement On Recent Spike In Flu Activity).

 

Regardless of the strain of flu in circulation, you are much better off avoiding infection rather than treating it. So while it may only provide moderate protection, getting the flu shot each year is cheap insurance. 

That, and following good flu hygiene practices (covering coughs, washing hands frequently, staying home when sick, avoiding close contact with those who are sick),  are your best defense against our yearly flu epidemic.

NPM13: Giving Preparedness A Shot In The Arm

Photo Credit PHIL

 

# 7759

 

Note: This is day 13  of National Preparedness Month.  Follow this year’s campaign on Twitter by searching for the #NPM  & NPM13 hash tag.

This month, as part of NPM13, I’ll be rerunning some edited and updated older preparedness essays, along with some new ones.

 

 

You might not have thought about it, but getting your seasonal flu shot each year should be part of your overall preparedness plan. During a disaster or prolonged emergency you are likely to be tired, stressed, and your immune systems could be weakened.

 

The last thing you need during a crisis is to be sick with the flu on top of it.

 

Which is why yesterday I paid a visit to my local CVS pharmacy and got my yearly seasonal flu shot.  The process (and the shot – nice job, Carol) were painless. And as an added bonus, I discovered that this year they were only offering single-dose (preservative-free) vaccines.

 

According to the CDC, more than 50 million doses of this year’s flu vaccine have already been distributed, so finding a shot should be no trouble.

 

Seasonal Influenza Vaccine & Total Doses Distributed

• This table reflects the cumulative weekly total number of seasonal influenza vaccine doses distributed in the US as reported to CDC by influenza vaccine manufacturers and selected distributors.
• Currently, manufacturers project 135-139 million doses of flu vaccine to be produced this season.

September 9, 2013 9:30 AM ET

 

September might seem a little early to be getting the flu shot, but we are already seeing scattered reports of influenza (see California, South Carolina & Florida) around the country, and it takes a couple of weeks after getting the shot for immunity to kick in. 

 

While the vaccine can’t promise 100% protection, it – along with practicing good flu hygiene (washing hands, covering coughs, & staying home if sick) – remains your best strategy for avoiding the flu this winter.

 

Recent studies (see A Comprehensive Flu Vaccine Effectiveness Meta-Analysis) have shown the flu shot to be moderately effective in preventing influenza – at least among healthy adults under the age of 65. As an added incentive, while far from conclusive, we’ve seen mounting evidence that the  Flu Vaccine May Reduce Heart Attack Risk.

 

For the elderly and for those with immune problems the flu vaccine’s effectiveness is often lower (see Study: Flu Vaccines And The Elderly).

 

In 2011, NFID - the National Foundation for Infectious Diseases - convened a group of experts to address the issues of influenza and the elderly. From that panel a 5-page brief has emerged, called: Understanding the Challenges and Opportunities in Protecting Older Adults from Influenza.

 

While the elderly generally see less protection from the flu vaccine, they state that older individuals may still mount a robust immune response. Even if the vaccine doesn’t always prevent infection in the elderly, studies suggest that the vaccine may blunt the seriousness of the illness in those over 65.

 

For those over 65, the option of taking the new high dose flu vaccine is now available (see MMWR On High Dose Flu Vaccine For Seniors). Early reports are encouraging, but we don’t have data yet on how much more effective it is among that cohort.

 

There is no doubt that we need better flu vaccines – particularly for those at greatest risk from influenza infection; the elderly and those with chronic illnesses (see CIDRAP: The Need For `Game Changing’ Flu Vaccines). But until they can be developed, the vaccines we have can and do help reduce the spread of the virus.

 

And lastly,  flu vaccines have excellent safety records.

 

Yes, taking any medicine – including a vaccine – entails some (usually miniscule) degree of risk. But those risks pale when compared to the dangers of catching the diseases they are designed to prevent. After all, Influenza sickens millions, and kills tens of thousands of people, every year in this country.

 

Ready.gov urges all Americans to follow these 3 steps to better preparedness:

GET A KIT

MAKE A PLAN

BE INFORMED

 

Sage advice. But if you want to be truly prepared, I would add an important 4th step.

 

Get a shot

Revisiting The Numbers Racket

 

 

 

# 6739

 

An excellent piece by Kelly Crowe of CBC News over the weekend questions the credibility of flu mortality numbers and reminds us, once again, that in public health easy answers are often the hardest to deliver.

 

First a link to the article, which I encourage you to read in its entirety. 

 

Flu deaths reality check

Credibility of flu models disputed

By Kelly Crowe, CBC News

Posted: Nov 25, 2012 5:14 PM ET

Do thousands of Canadians really die every year from the flu? The flu folks keep saying so. I've already heard it repeated several times this year and flu season has just started. This is what the Public Health Agency of Canada said in a recent press release: "Every year, between 2,000 and 8,000 Canadians die of the flu and its complications."

(Continue . . . )

 

 

Long time visitors to this blog will recall that we’ve trod this perilous path before - for both seasonal and pandemic flu - along with a variety of other diseases.  

 

Quite understandably, the public and the media expect public health officials to have some kind of handle on the number of deaths caused by infectious diseases in our society. 

 

Particularly with something as ubiquitous as flu.

 

But the truth is, no one really knows.

 

After more than a decade of promoting the `flu kills roughly 36,000 Americans each year’ meme, the CDC revised (and hopefully improved) their estimates in 2010 ( see MMWR: Estimates Of Yearly Seasonal Influenza Deaths)

 

For deaths with underlying pneumonia and influenza causes (the most narrow definition of flu-related fatalities used) the models estimated a yearly average of 6,309 (range: 961 in 1986--87 to 14,715 in 2003--04) influenza-associated deaths.

 

Using a broader criteria (underlying respiratory and circulatory causes including pneumonia and influenza causes)  the models estimated an annual average of 23,607 (range: 3,349 in 1986--87 to 48,614 in 2003--04) influenza-associated deaths.

 

Despite the 12-fold difference in deaths between the 1986-87 and 2003-04 seasons, the operative word here remains `estimated’. 

 

• Estimates are extrapolated based on a surveillance subset of the country, not the whole nation
• There are often co-circulating viruses that may influence overall mortality.
• Surveillance, testing, and reporting may change over time
• Different mathematical models can produce differing results
• There are varying opinions as to what constitutes an influenza-related fatality.

 

When combined with the inevitable variations in the severity of influenza seasons (H3 years are usually more severe than H1 years), this makes it impossible to derive a single number that `works’.

 

In an attempt not to compound a felony, I try to leave it as influenza `kills thousands each year’ or `is the cause of substantial mortality’ in this blog. Sometimes I’ll use the range (3,000-48,000) offered by the CDC, but most of the time I don’t.

 

The same holds true for just about any illness or disease you’d care to mention. 

 

Ask the CDC how many people contracted West Nile Fever this summer, and they will tell you that (as of Nov. 20th) they had recorded  5,207 cases of West Nile virus disease in people, including 234 deaths, but that the real number may be 50 times higher.

Severe (neuroinvasive) cases are pretty easy to spot, but they estimate only 1%-3% of mild cases of West Nile Fever are diagnosed and reported.

 

If we do the math, and assume the 2654 non-neuroinvasive cases officially reported constitute between 1% and 3% of the total number of actual cases we get a range of between 250,000 and 85,000 infections.

 

The chart below illustrates the problem nicely. 

 

 

Relying only on lab confirmed fatalities isn’t much of a solution, either. The `official’ death toll for the 2009 pandemic - as reported by the World Health Organization  - was roughly 18,000 deaths globally.

 

The WHO offered this disclaimer:

 

The reported number of fatal cases is an under representation of the actual numbers as many deaths are never tested or recognized as influenza related. – World Health Organization.

 

Unfortunately, the mainstream media often reported the low official number of deaths without adequately explaining the acknowledged gaps in the data, leading many to believe that the 2009 pandemic was a damp squib.

 

In contrast, earlier this year, in Lancet: Estimating Global 2009 Pandemic Mortality, we saw a study who’s estimate found:

 

We estimate that globally there were 201 200 respiratory deaths (range 105 700—395 600) with an additional 83 300 cardiovascular deaths (46 000—179 900) associated with 2009 pandemic influenza A H1N1. 80% of the respiratory and cardiovascular deaths were in people younger than 65 years and 59% occurred in southeast Asia and Africa.

 

 

With no way to accurately count cases, analysts are reduced to creating mathematical models, fueled by both hard data and assumptions, in order to extrapolate the impact of diseases on the population.

 

The old adage (well, not that old, as it is attributed to George E. P. Box, Professor Emeritus of Statistics at the University of Wisconsin) is that:

 

“All models are wrong, but some models are useful.”

 

To that I would add, that while useful, mathematical models can be extraordinarily difficult to defend.

 

It requires agreement over assumptions.  And among academics, that’s never easy to reach.

 

Going hand-in-hand with the estimates of flu deaths each year has been the purported effectiveness of the seasonal flu shot.

 

Up until about a year ago the CDC’s mantra has been for healthy adults under the age of 65, in years when the vaccine is a good match to circulating strains, effectiveness ranges from 70%-90%.

 

Despite these important qualifiers, the message often ended up being shortened in the media to the flu vaccine being `up to 90% effective’.

 

A little more than a year ago the CDC updated their FAQ on Flu Vaccine effectiveness, and as part of a much longer detailed posting, lowered their estimate of the inactivated flu shot’s effectiveness to read:

 

. . . recent RCTs of inactivated influenza vaccine among adults under 65 years of age have estimated 50-70% vaccine efficacy during seasons in which the vaccines' influenza A components were well matched to circulating influenza A viruses.

 

A number that pretty much matched CIDRAP’s finding (see A Comprehensive Flu Vaccine Effectiveness Meta-Analysis) which would be released a couple of weeks later. That analysis showed the trivalent inactivated vaccine (TIV) had a combined efficacy of 59% among healthy adults (aged 18–65 years).

 

So what are we left with?

 

Well, every time we get into statistics (admittedly not my strong suit) I’m reminded of the story of the statistician who drowned trying to ford a river that was, on average, only 3 feet deep.

 

Still I think we can safely draw a few conclusions.

 

Influenza-like-Illnesses (ILIs) obviously contribute to a good deal of morbidity and mortality each year. 

 

In addition to influenza, these illnesses can be caused by the metapneumovirus, parainfluenzavirus, respiratory syncytial virus (RSV), adenoviruses, or any of the myriad Rhinoviruses (Common cold).  Among others.

 

The percentage of these illnesses that are actually due to the influenza virus varies considerably from year to year, and so only a portion of these deaths are actually `vaccine preventable’.

 

Today’s influenza vaccine, whose effectiveness is described as just `moderate’ by CIDRAP’s recent 160-page Comprehensive Influenza Vaccine Initiative (CCIVI) report, undoubtedly saves lives and reduces hospitalization, but is not the panacea that many would hope for.

 

 

Hence the call for better vaccines.  

 

Despite their limitations, I still get a flu vaccine each year, as I believe partial protection beats no protection any day of the week.

 

As far as the estimate of deaths from influenza are concerned, I doubt this debate can really be solved to everyone’s satisfaction. There is no single, `good’ answer when the parameters change as often as they do with influenza.

 

We live in a world driven by easily adopted memes, 10 second sound bytes, and 140 character tweets.

 

As a result, officials are often tempted to provide us with simplified, easy to digest, answers. While brevity may have many advantages, scientific precision is rarely one of them. 

 

Of course, if someone comes up with a better way to measure the number of deaths from influenza each year, I’ll feature it in this blog.  Until that happens, I’ll simply leave it as the cause of `substantial mortality’.