#15,385
Last week, in The `Other' Vaccine Challenge This Fall, we looked at some of the anticipated logistical problems in this fall's flu vaccination campaign - which like everything else these days - must be conducted against the backdrop of our ongoing COVID-19 pandemic.
No one really knows what to expect with our fall and winter flu season, although there are naturally concerns about dealing with two simultaneous epidemics.
A bad influenza season could make diagnosing COVID cases more difficult, and at the same time substantially add to the pandemic's burden on hospital resources. But curiously, very little flu has been reported anywhere in the world since April, even in the Southern Hemisphere where it is normally at its seasonal peak.
This drop off is likely due to the social distancing and PPE measures (face covers, hand hygiene, etc.) being taken against COVID-19, aided and abetted by a reallocation of surveillance resources to the pandemic.
Whether this trend will continue into the Northern Hemisphere's flu season is anyone's guess.
Two months ago, in COVID-19, The Next Flu Season, And The Temporary Immunity Hypothesis, we looked at the complex and poorly understood dynamics of co-circulating respiratory viruses, and the possibility that getting infected with one virus might (temporarily) reduce your chances of being infected by another.
The reality is, we can't wait to see whether flu returns this fall or winter to begin to give out flu shots. The vaccine takes a couple of weeks to take effect, and we can't vaccinate 150 million people on short notice, particularly in the midst of a COVID-19 pandemic.
So this year, like every year, we will go into a flu season of unknown intensity. And we won't know how effective this year's flu vaccine will be until well into the flu season.
None of this is to argue against getting the flu shot. I will get it again this year (my 16th year running), and while getting the flu vaccine isn't an ironclad guarantee of avoiding infection, most years it provides moderately good protection against circulating influenza viruses.
And according to the CDC, for those who are vaccinated - but still get the flu - they are less likely to have a severe bout.
But increasingly influenza and other respiratory infections have also been linked to a significant seasonal increase in heart attacks and strokes.
- Last September, in PLoS One: Transient Depression of Myocardial Function After Influenza Virus Infection, we looked at a study that found transient myocardial function changes among a small group of influenza patients studied.
- In 2018's NEJM: Acute Myocardial Infarction After Laboratory-Confirmed Influenza Infection, we saw a study that found a `significant association ' between recent (lab confirmed) influenza infection and Myocardial Infarction.
- And in May 2017, in Int. Med. J.: Triggering Of Acute M.I. By Respiratory Infection we looked at research from the University of Sydney that found the risk of a heart attack is increased 17-fold in the week following a respiratory infection such as influenza or pneumonia.
Despite some less-than-stellar influenza Vaccine Efficiency (VE) numbers - particularly among those in the highest risk groups (65+) - we've seen evidence that vaccination does reduce complications like heart attacks and strokes.
- In 2015, in UNSW: Flu Vaccine Provides Significant Protection Against Heart Attacks,we saw a study that found that if you are over 50 - getting the flu vaccine can cut your risk of a heart attack by up to 45%.
- In 2018, a study appearing the American Heart Association's journal Circulation, found a substantial reduction in deaths among heart failure patients who received a yearly flu shot (see AHA: Study Shows Flu Shots Reduce Deaths From Heart Failure).
- Eighteen months ago, in Chest: Flu Vaccine Reduces Severe Outcomes Among Hospitalized Patients With COPD, researchers found a lower mortality rate, less critical illness, and a 38% reduction in influenza-related hospitalizations in vaccinated vs unvaccinated individuals.
- And last summer, in Flu Vaccine May Lower Stroke Risk in Elderly ICU Patients, we saw a study that found influenza vaccinated ICU survivors had a lower 1-year risk of stroke and a lower 1-year risk of death than unvaccinated survivors.
First a link and excerpt from the AAIC press release (and abstract). Follow it to read it in its entirety, I'll have a postscript when you return.
FROM THE ALZHEIMER’S ASSOCIATION INTERNATIONAL CONFERENCE 2020
CHICAGO, JULY 27, 2020 — Flu (influenza) and pneumonia vaccinations are associated with reduced risk of Alzheimer’s disease, according to new research reported at the Alzheimer’s Association International Conference ® (AAIC®) 2020.Three research studies reported at AAIC 2020 suggest:
● At least one flu vaccination was associated with a 17% reduction in Alzheimer’s incidence. More frequent flu vaccination was associated with another 13% reduction in Alzheimer’s incidence.● Vaccination against pneumonia between ages 65 and 75 reduced Alzheimer’s risk by up to 40% depending on individual genes.● Individuals with dementia have a higher risk of dying (6-fold) after infections than those without dementia (3-fold).
“With the COVID-19 pandemic, vaccines are at the forefront of public health discussions. It is important to explore their benefit in not only protecting against viral or bacterial infection but also improving long-term health outcomes,” said Maria C. Carrillo, Ph.D., Alzheimer’s Association chief science officer.
The paper's abstract can be read at the following link:
Some past blogs on neurological diseases tentatively linked to viral infections include:
The Lancet: COVID-19: Can We Learn From Encephalitis Lethargica?
Neuroinfluenza: A Review Of Recently Published Studies
JNeurosci: Another Study On The Neurocognitive Impact Of Influenza Infection
The exact mechanisms behind these neurological manifestations are unknown, as seasonal flu viruses are generally not regarded as being neurotropic. But some researchers have suggested that these neurological symptoms may be due to neuroinflammation induced by the host's immune response.
While we are still short of having absolute proof that flu vaccines provide tangible protection against developing Alzheimer's or Parkinson's disease - or can greatly reduce the odds of having a post-infection heart attack or stroke - the evidence continues to mount suggesting it is at least plausible.
Which is why I'll be rolling up my sleeve again this fall. I'll happily settle for some degree of short-term protection against influenza, and consider any potential long-term benefits a bonus.
Because now that I'm in that dreaded `high risk' age group, I can use any advantage I can get.
