J. Global Health: Global Distribution and Health Impact of Infectious Disease Outbreaks, 1996–2023 (A Retrospective Analysis)

 

#18,723

In 2017 (and again in 2018) the WHO released a short list (n=8) of priority diseases (see WHO List Of Blueprint Priority Diseases) - that in their estimation had the potential to spark a public health emergency and were in dire need of accelerated research:

• Crimean-Congo haemorrhagic fever (CCHF)
• Ebola virus disease and Marburg virus disease
• Lassa fever
• Middle East respiratory syndrome coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS)
• Nipah and henipaviral diseases
• Rift Valley fever (RVF)
• Zika
• Disease X

As it turned out, a variant of #4 on their list (SARS-MERS) sparked the worst pandemic in a century less than 3 years later, while we've seen repeated outbreaks from the others. 

Last summer the WHO unveiled an expanded 38-page Pathogens Prioritization report, increasing the number of priority pathogens to more than 30. Additions included 7 different influenza A subtypes (H1, H3, H3, H5, H6, H7, and H10), and 5 bacterial strains that cause cholera, plague, dysentery, diarrhea and pneumonia. 

 Today we've a retrospective analysis of disease outbreaks reported to the WHO from around the globe since 1996, which find > 3,000 significant events. Central Africa (DRC) and China (see Viral Reassortants: Rocking The Cradle Of Influenza) lead the pack, followed by the Middle East and parts of Southeast Asia. 

They report: 

Influenza was the most frequently reported disease, with a total of 771 outbreak events, followed by Ebola virus and MERS-CoV. Other frequently reported diseases included yellow fever, cholera, and meningitis. 

But of course, not every outbreak is reported, and the details on those that are can sometimes be sparse. 

This is a lengthy and fairly detailed retrospective, so I've only reproduced the link and abstract below.  Follow the link to read it in its entirety.  I'll have a postscript after the break.

May 16, 2025

Global distribution and health impact of infectious disease outbreaks, 1996–2023: a worldwide retrospective analysis of World Health Organization emergency event reports

Qiao Liu1, Min Liu1,2,3, Wannian Liang4,5, Xuanjun Li1, Wenzhan Jing5,6, Zhongdan Chen7, Jue Liu1,2,3,8,9

Abstract

Background

Over 30 priority pathogens with pandemic potential were identified, underscoring the need for targeted surveillance and prevention. As infectious disease outbreaks increase globally, particularly from zoonotic and vector-borne pathogens, understanding their distribution is crucial for effective public health responses. We aimed to provide a comprehensive analysis of global infectious disease outbreaks from 1996–2023, addressing gaps in previous research.

Methods

We sourced data from the World Health Organization emergency events webpage, focusing on key details like disease name, location, date, and fatalities. We calculated case fatality rates (CFR) to assess outbreak severity. We categorised outbreaks into six types – respiratory, vector-borne, foodborne/waterborne, direct contact infections, non-infectious conditions, and others. Data extraction was independently performed and cross-verified for accuracy.

Results

Between 1996–2023, a total of 3013 global outbreak events were reported. The Democratic Republic of the Congo had the highest frequency of outbreaks, with 272 events, followed by China with 254, and Saudi Arabia with 202. Influenza was the most frequently reported disease, with 771 outbreaks, followed by Ebola (n = 342) and Middle East respiratory syndrome-related coronavirus (MERS-CoV) (n = 305). Significant outbreaks included the 2023 global dengue outbreak, which accounted for five million cases and 5000 deaths. The CFR was highest for the Marburg virus at 76.86%, followed by haemorrhagic fever at 63.63%, and Ebola at 63.00%. The data underscore the varying severity and distribution of outbreaks, highlighting the critical need for robust global health surveillance and targeted interventions.

Conclusions

In this study, we highlighted the significant impact of influenza, Ebola, and MERS-CoV. The high case fatality rates of viruses like Marburg and Ebola emphasised the need for early detection and rapid response systems. Strengthening global cooperation, investing in health care infrastructure, and integrating digital surveillance technologies are crucial to enhancing preparedness and reducing future outbreak impacts.

          (Continue . . . )

In the 1990s researcher George Armelagos of Emory University posited that since the mid-1970s the world had entered into an age of newly emerging infectious diseases, re-emerging diseases and a rise in antimicrobial resistant pathogens (see The Third Epidemiological Transition (Revisited). 

And the following timeline, from the UK HAIRS group would seem to bear that out.

UK HAIRS Timeline - 20 years of Emerging Viruses

Emerging infectious diseases have become such an important public health threat that the CDC maintains as special division – NCEZID (National Center for Emerging and Zoonotic Infectious Diseases) – to deal with them, and in the 1990s the CDC established the EID Journal dedicated to research on emerging infectious diseases.

Recent studies suggest that the frequency, and impact, of pandemics are only expected to increase over the next few decades.

BMJ Global: Historical Trends Demonstrate a Pattern of Increasingly Frequent & Severe Zoonotic Spillover Events

PNAS Research: Intensity and Frequency of Extreme Novel Epidemics

And yet, at this critical juncture in history, we are dismantling our disease surveillance, investigative, and reporting systems at a furious rate (see Flying Blind In The Viral Storm). Many nations - including our own - have chosen to ignore the IHR 2005 regulations and stop (or severely limit) reporting to the WHO and WOAH on outbreaks (see From Here To Impunity).

While I can't tell you if H5Nx,  MERS-CoV, or Nipah will spark the next pandemic, one thing is all but certain; Something will.  

And when that happens, we'll regret every day we squandered not aggressively preparing for its arrival. 

Eurosurveillance: Air and Surface Sampling for Clade Ib Monkeypox Virus in United Kingdom Hospitals, 2024 to 2025

Monkeypox Virus - Credit CDC PHIL

#18,722

While the public often dismisses mpox as a `niche' or `lifestyle' disease - and unlikely to affect them - it is a cousin to the smallpox virus which (during the 20th century alone) killed hundreds of millions of people (cite).

Last January, the CDC published a review called The Rise of Mpox in a Post-Smallpox World, which characterized the virus as having `pandemic potential' no less than 4 times.

Reports of mpox are rising in Africa where the disease is endemic and in new countries where the disease has not been previously seen. The 2022 global outbreak of clade II mpox and an ongoing outbreak of the more lethal clade I mpox highlight the pandemic potential for monkeypox virus.

Waning population immunity after the cessation of routine immunization for smallpox plays a key role in the changing epidemiologic patterns of mpox. Sustained human-to-human transmission of mpox is occurring widely in the context of insufficient population immunity, fueling genetic mutations that affect the accuracy of some diagnostic tests and that could lead to changing virulence.

We've been following the evolution and spread of mpox (formerly Monkeypox) in this blog for more than 15 years, including studies warning of its increasing threat. 

We now have at least 4 clades of Mpox in circulation (I, Ib, II, IIb), with Clade Ia and Ib considered the most severe. Two clades (IIb and Ib) have managed to spread internationally, and the WHO's most recent risk assessment puts their global risk as Moderate to High.

Although the vast majority of Mpox cases outside of Africa have occurred among men who reported recent male-to-male sexual contact (MMSC), a small - but notable - number of cases reported no such activity.

A 2023 MMWR report (Possible Exposures Among Mpox Patients Without Reported Male-to-Male Sexual Contact). suggested other possible routes - including fomites - might be a factor. Since 2022 we've seen several studies on extensive environmental contamination with the Mpox virus - both in household and hospital settings - including:

MMWR: High-Contact Object & Surface Contamination in a Household of Persons with Monkeypox Virus Infection

EID Journal: Environmental Persistence of Monkeypox Virus on Surfaces in A Household

Eurosurveillance: Surface Contamination in Hospital Rooms Occupied by Patients Infected with Monkeypox

Admittedly, viral DNA may be detected, even when the virus is no longer viable or is in concentrations too low to be infectious. But in the EID Journal report above, researchers were able to isolated viable MPXV on household surfaces after at least 15 days, although low titers (<102 PFU) suggested a limited potential for indirect transmission. 

All of which brings us to a new study published in Eurosurveillance, conducted by the UKHSA, on environmental contamination from Mpox clade Ib in a hospital setting. Viral DNA was detectable in > 70% of samples taken.

 

The results are similar to those reported (above) from clade IIb studies in 2022-2023. 

I've only posted the link and some excerpts. You'll want to follow the link to read the study in its entirety.  I'll have a bit more after the break. 

Air and surface sampling for clade Ib monkeypox virus in United Kingdom hospitals, 2024 to 2025  
Barry Atkinson1,2 , Susan Gould2,3,4 , Ian Nicholls1 , Khanzadi Nazneen Manzoor1 , Jack Smith1 , Andrew J. Hindle5 , Anne J. Tunbridge5 , Joby Cole5,6 , Paul Collini5,6 , Alejandra Alonso7 , Geraldine O’Hara8 , Cecilia Tuudah8 , Jonathan A. Otter8 , Berkin Hack8 , Caroline Taylor9 , Thomas Pottage1 , Tom Fletcher2,3,4 , Jake Dunning2,9,10

Between late October 2024 and the end of January 2025, the first eight patients with clinical symptoms of clade Ib monkeypox virus (MPXV) infection were identified in the United Kingdom (UK). Seven of them were admitted for clinical observation and monitoring to airborne high consequence infectious disease (HCID) centres. To understand if the immediate environment of patients with clade Ib mpox can become contaminated with MPXV, we investigated whether this virus could be detected in environmental surface and air samples collected from the seven patients’ rooms or anterooms.

          (SNIP)

Environmental sampling in isolation rooms
 
Environmental air and surface sampling was conducted as previously described [2]. Briefly, environmental sampling was performed on seven separate occasions in rooms occupied at the time by patients with confirmed clade Ib MPXV infection (five sampling events) or ca 16 hours post discharge of patients with confirmed clade Ib MPXV infection (two sampling events). One of these sampling events took place in a room occupied by two co-habiting infected individuals (Cases 2 and 3), and two separate sampling events were performed around the same individual 6 days apart (Case 5). The sampling scheme aimed to sample the same surfaces in all rooms and to collect air samples both before and during a bed linen change; however, minor variations were made to account for different room set-ups, such as the absence of a sink in one of the patient-rooms.

         (SNIP)  

MPXV DNA was detected in 66/90 surface samples collected (Table 2). Unsurprisingly, samples from frequently touched points often contained detectable MPXV DNA, with MPXV detected in bathroom tap handle samples collected during all seven sampling events. Similarly, the shower handle and toilet flush samples contained detectable MPXV DNA from six of seven sampling events.

         (SNIP)

Discussion

The results from the currently reported investigations confirm that clade Ib mpox patients contaminate their immediate environment and that infection-competent virus may be present, which may pose a risk of onward transmission. While it is not possible to accurately quantify this risk using data from these investigations, they do support the need for defined infection prevention and control (IPC) measures when cases are detected to minimise the risk of exposure to viable virus in the environment that could present a transmission risk.

Findings from these environmental sampling investigations broadly align with those from studies performed in healthcare settings during the 2022 clade IIb public health emergency of international concern (PHEIC) [2,5-10]. Such information may contribute to the discussion regarding potential phenotypic differences between clade Ib and IIb MPXV; however, it is important to note the small sample size in both datasets. 

Our investigations again demonstrate that MPXV can be detected in air samples collected when bed linen is changed; however, detection of MPXV in air samples was uncommon in this study (only one of seven bed linen-change samples contained detectable MPXV DNA), despite the inclusion of some patients with high lesion-counts.

          (Continue . . ,)

We have a long history of underestimating or pigeonholing viruses, thinking that the way they behaved yesterday, and the day before, tells us how they will behave tomorrow and all the days, weeks, and years that follow.

It may be comforting, but that isn't how viruses - and evolution - work.

We've seen recent reports of  household transmission' of mpox clade Ib (including to children) in the UK (see Eurosurveillance report), and in Germany and Belgium (see ECDC: Epidemiological Update).

Last month, the UK reported their first `community acquired' case of Mpox clade Ib; one with no travel history or link to a previously identified case.  The numbers may be limited, but they serve as a proof of concept.

Making the better we understand the ways this virus can spread, the better our chances of containing it. 

PAHO: Epidemiological Update Avian Influenza A(H5N1) in the Americas Region (May 15th)

 

#18,721

It's been just over 2 months since the last epidemiological update on H5N1 was published by PAHO (the Pan American Health Organization), and while the number of of new cases reported by the United States has slowed, the threat has not gone away. 

In April, we saw Mexico Report their 1st Human H5N1 Case in a 3-year old girl from (largely agricultural) Durango State, and a couple of weeks later we looked at WHO Guidance: Surveillance for Human Infections with Avian Influenza A(‎H5)‎ Viruses which urged member nations to step up surveillance and reporting.

How much testing, and sharing of information, is really going on is difficult to say.  

While the 2005 IHR agreement requires nations to report certain disease outbreaks and public health events to the WHO in a timely manner, this goal has long been hampered by a lack of any enforcement options in the agreement (see Adding Accountability To The IHR). 

Last March, in Nature: Lengthy Delays in H5N1 Genome Submissions to GISAID, we learned that the average delay for submitting non-human sequences was 7 months, and that Canada came in last at 20 months.  

I've only posted the link and some excerpts from the 12-page PDF report.  Follow the link to read it in its entirety.

Epidemiological UpdateAvian Influenza A(H5N1)in the Americas Region15 May 2025

Global Context

In 2020, the highly pathogenic avian influenza (HPAI) virus1 subtype H5N1 of clade 2.3.4.4b caused an unprecedented number of deaths in wild birds and poultry in numerous countries in Africa, Asia, and Europe (1). In 2021, this virus spread through major waterfowl flyways to North America and, in 2022, to Central and South America (1). By 2023, outbreaks in animals were reported from 14 countries and territories, mainly in the Americas (1, 2).

In recent years, there has been an increase in the detection of the influenza A(H5N1) virus in non-avian species worldwide, including terrestrial and marine mammals, both wild and domestic (companion and production). Since 2022, 22 countries on three continents, including the Americas, have reported outbreaks in mammals to the World Organisation for Animal Health (WOAH) (3).

Historically, since the beginning of 2003 and as of 22 April 2025, 973 human cases of avian influenza A(H5N1), including 470 deaths (48% case fatality rate), were reported to the World Health Organization (WHO) from 25 countries globally (4).

Summary of the situation in the Americas Region

Since 2022 and as of epidemiological week (EW) 18 of 2025, a total of 19 countries and territories2 in the Americas Region reported 4,948 animal outbreaks3 of avian influenza A(H5N1) to WOAH (3), representing 235 additional outbreaks since the last epidemiological update on avian influenza A(H5N1) published by the Pan American Health Organization/World Health Organization (PAHO/WHO) on 4 March 2025 (3, 5).

Since 2022 and as of 12 May 2025, 75 human infections caused by avian influenza A(H5) have been reported in five countries in the Americas, with one additional case reported since the 4 March 2025 PAHO/WHO epidemiological update on avian influenza A(H5N1) (Figure 1) 6).

The most recent human case of avian influenza A(H5N1) reported in the Americas Region was reported in Mexico on 2 April 2025 (6-8), 71 cases have been reported in the United States of America – one in 2022 and 70 since 2024 (9), one case in Canada was confirmed on 13 November 2024 (10), one case in Chile was reported on 29 March 2023 (11), and one case in Ecuador was reported on 9 January 2023 (12).

          (SNIP)

PAHO/WHO urges Member States to work collaboratively and in an intersectoral manner to preserve animal health and protect public health. It is essential that preventive measures for avian influenza be implemented at the source, protocols for detection, notification and rapid response to outbreaks in animals be established, surveillance for both animal and human influenza be strengthened, epidemiological and virological investigations be carried out in relation to animal outbreaks and human infections, genetic information about viruses be shared, thereby fostering collaboration between animal and human health settings, effectively communicating risk , and ensuring preparedness for a potential influenza pandemic at all levels (30, 31).

          (Continue . . . ) 

Eurosurveillance: Human Infections with Eurasian Avian-like Swine Influenza Virus Detected by Coincidence Via Routine Respiratory Surveillance Systems, the Netherlands, 2020 to 2023

 

#18,720

Conventional wisdom holds that swine variant flu infections don't transmit well in humans, and that most of the (rare) cases reported are due to exposure to pigs; usually on farms or at agricultural exhibits.  

While largely true, there are a few caveats. Primarily that swine variant infections are generally mild, and are undisguisable from seasonal colds or flus without specialized laboratory testing. Something that is rarely done for flu patients who are mildly ill. 

Over the years we've seen estimates that the cases we see are likely only the tip of the iceberg.  A dozen years ago, during a small outbreak (n=13) of H3N2v in the United States - researchers estimated that fewer than 1 in every 200 cases was identified (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012).

Results. We estimate that the median multiplier for children was 200 (90% range, 115–369) and for adults was 255 (90% range, 152–479) and that 2055 (90% range, 1187–3800) illnesses from H3N2v virus infections may have occurred from August 2011 to April 2012, suggesting that the new virus was more widespread than previously thought. 

We've seen similar estimates with other novel viruses, including H7N9 in China and MERS-CoV in Saudi Arabia, while seroprevalence studies have indicated that spillovers of H9N2 - and even H5N1 - often go unreported. 

While there is no evidence of sustained transmission of swine variant influenza, we have seen a significant number of sporadic cases which report no (direct or indirect) contact with pigs, which raises questions about how that person was exposed.  

A little over a month ago, in Emerg. Microbes & Inf.: Eurasian 1C Swine Influenza A Virus Exhibits High Pandemic Risk Traits, we looked at growing concerns over the Eurasian avian-like swine influenza A(H1N1)v virus clade 1C.2.1, which has become endemic in pig populations in Europe and Asia. 

They reported: 

Since 2010, at least 21 spillover events of 1C virus into humans have been detected and three of these occurred from July to December of 2023.

         and

The 1C virus exhibited phenotypic signatures similar to the 2009 pandemic H1N1 virus, including human receptor preference, productive replication in human airway cells, and robust environmental stability. Efficient inter- and intraspecies airborne transmission using the swine and ferret models was observed, including efficient airborne transmission to ferrets with pre-existing human seasonal H1N1 immunity. Together our data suggest H1 1C influenza virus poses a relatively high pandemic risk.

Yesterday's Eurosurveillance reports on 3 swine 1C cases serendipitously detected through routine surveillance since 2020 - 2 of which had no direct contact with pigs -  from the Netherlands.  They key messages being:

The Eurosurveillance report is lengthy and informative, and worth reading in its entirety. I've posted the link and some excerpts below.  I'll have a bit more when you return. 

Human infections with Eurasian avian-like swine influenza virus detected by coincidence via routine respiratory surveillance systems, the Netherlands, 2020 to 2023 

Dirk Eggink1, Annelies Kroneman1 , Jozef Dingemans2 , Gabriel Goderski1 , Sharon van den Brink1 , Mariam Bagheri1 , Pascal Lexmond3 , Mark Pronk3 , Erhard van der Vries5 , Evelien Germeraad4 , Diederik Brandwagt1 , Manon Houben5 , Mariëtte van Hooiveld6 , Joke van der Giessen1 ,  Ron Fouchier3 , Adam Meijer1

Sporadic human infections with avian or swine influenza A virus (swIAV) have been reported. Zoonotic influenza, including human infections with avian influenza A virus or swIAV, is notifiable in the Netherlands and national and international guidelines state that local and national public health services need to be timely notified of laboratory-confirmed cases allowing source finding and contact tracing.

Swine influenza A viruses are genetically and antigenically distinct for different continents, due to introductions into pig populations from different origins and at different time points. Limited inter-continental spread between pigs or pig farms seems to occur [1-3]. In Europe, four swIAV haemagglutinin (HA) lineages are enzootic:

• H1 classical swine lineage (clade 1A) including H1pdm09-like viruses,
• H1 human seasonal lineage (clade 1B),
• H1 Eurasian avian-like lineage (clade 1C)
• and European human-like H3 lineage.

These HA lineages are combined with four neuraminidase (NA) lineages: N1pdm09-like, avian N1 and two swine N2 lineages. Knowledge about circulating genotypes of swIAV is limited and difficult to obtain due to limited surveillance of swIAV on pig farms in most countries in Europe, including the Netherlands, especially after the European Surveillance Network for Influenza in Pigs (ESNIP 3) was terminated in 2013 [1].

Human infections with swIAV have been detected sporadically in Europe whereas in the United States (US), such infections have been detected more frequently [2,4-6]. These infections occurred mainly after close contact with infected pigs on agricultural fairs [5]. In addition, the A(H1N1)pdm09 pandemic in 2009 was highly likely caused by direct spillover from infected pigs and subsequent human-to-human transmission [7].

In the Netherlands, swIAV was detected in six persons 1986–2019 [4,8-13]. The previous detections of swIAV infections in humans in the Netherlands were mostly coincidental, in hospitalised persons presenting with severe disease [10], as no surveillance system to detect zoonotic spillovers from pigs to humans is in place with the aim to monitor specific risk groups upon exposure. This contrasts with monitoring of individuals exposed to poultry infected with highly pathogenic avian influenza A virus (HPAI) for which passive and active monitoring is in place in the Netherlands.

Here we describe detection of Eurasian swIAV infection in three persons during routine influenza surveillance activities in 2020, 2022 and 2023 in the Netherlands. 

          (SNIP)

Interestingly, the three patients described here were detected via routine surveillance systems and NIC activities. The occurrence of these infections outside the traditional respiratory season is remarkable, although it is not possible at this point to draw conclusions about the risk of infection during or outside the respiratory season.

In the Netherlands, there is no passive or active surveillance of humans exposed to pigs infected with swIAV, like farmers, their family members, veterinarians or individuals involved in transport or slaughtering of pigs. The experience in the US with swIAV exposure and human infections associated with visits to agricultural fairs suggests that close contact could be a major factor in zoonotic transmission, although the lack of direct exposure to (infected) pigs in two out of the three patients described, illustrates that other routes of transmission could exist.

Due to the possible cross-reactivity of anti A(H1N1)pdm09-like antibodies, present in most, if not all, humans, with the zoonotic viruses, serological assays could not be used for source and contact tracing to investigate possible unnoticed human-to-human transmission.

This likely results in underreporting of human infections with swIAV, in particular, as most patients with ILI in the general population are not sampled, let alone subtyped, especially those from mild to moderately severe cases that do not seek healthcare [28]. Therefore, (mild) human infections with swIAV could easily remain undetected.

Undetected infections might result in human adaptation by adaptive mutations or reassortment with seasonal influenza viruses, which could increase risk for human-to-human transmission.

          (Continue . . . ) 

While avian flu currently gets the bulk of our attention due to the rapid evolution and spread of HPAI H5N1, we also keep close tabs on swine flu, because pigs are considered to be excellent reservoirs and `mixing vessels' for influenza. 

While there are numerous swine-variants around the world, here in the United States the CDC has identified 3 as having some pandemic potential. 

• H1N2 variant [A/California/62/2018] Jul 2019 5.8 5.7 Moderate
• H3N2 variant [A/Ohio/13/2017] Jul 2019 6.6 5.8 Moderate
• H3N2 variant [A/Indiana/08/2011] Dec 2012 6.0 4.5 Moderate

The CDC currently ranks a Chinese Swine-variant EA H1N1 `G4' as having the highest pandemic potential of any flu virus on their list. But there are others worth noting, including the H1pdm09N1av virus in Danish pigs and repeated spillovers of H1N2v in Brazil.

And of course, we now have increased concerns over the potential for avian H5N1 to spillover into pigs, as it already has with dairy cows.  Thus far, only two pigs have tested positive in the United States, but elsewhere in the world we've seen sporadic reports of spillovers.

WHO H5N1 detected in pigs in China (2004)

EID Journal: Asymptomatic H5N1 In Pigs (2010)

An Unusual Report Of H5N1 in Pigs (Indonesia 2016)

Sci. Rpts.: Evidence Of H5N1 Exposure In Domestic Pigs - Nigeria (2018)

Seroconversion of a Swine Herd in a Free-Range Rural Multi-Species Farm against HPAI H5N1 2.3.4.4b Clade Virus (2023)

But the reality is, most of the world isn't even looking.  Even here in the United States, testing of pigs for novel flu viruses is largely voluntary and anonymous. Since pigs are generally able to carry novel flu viruses (including H5N1) asymptomatically, passive surveillance is unlikely to detect infections. 

While most of the emerging novel viruses we look at in this blog will probably never pose a genuine global health threat - there are a lot of contenders out there - and it only takes one overachiever to make an indelible mark on the world.  

The NERC 2025 Summer (Electrical Grid) Reliability Assessment

 

#18,719

Last month's 18-hour blackout across most of Spain, Portugal, and parts of France - which followed a nearly 48-hour grid down event in Puerto Rico two weeks before - is a reminder how easily our world can be turned upside down by an infrastructure failure, natural disaster, or malicious attack.

While the cause of Europe's blackout continues to be investigated, the fact is prolonged power outages have become increasingly common, due to the increased load on power systems and the number weather-related disasters around the globe. 

During 2024 the United States saw 27 Billion-dollar weather disasters, resulting in the deaths of at least 568 people, and economic losses of over $180 billion dollars.  Many involved prolonged power outages. 

In addition to ageing infrastructure, and ever increasing power demands, there are threats from cyber attacks (see DHS: NIAC Cyber Threat Report), solar flares and CMEs (see FEMA: Preparing the Nation for Space Weather Events), and even potential disruptions due to earthquakes, volcanic eruptions, and tsunamis. 

These are serious enough threats that in December of 2018, in NIAC: Surviving A Catastrophic Power Outage, we looked at a NIAC (National Infrastructure Advisory Council) 94-page report that examined the United State's current ability to respond to and recover from a widespread catastrophic power outage. 

It is the job of the North American Electric Reliability Corporation (NERC) to "ensure the reliability of the North American bulk power system", a mandate given to it in 2006 as a result of the 2003 Northeast blackout which affected more than 50 million people in the United States and Ontario, Canada.

Yesterday (May 14th) NERC released their 2025 Summer Grid Reliability Assessment (54 pages, PDF), which warns:

Record Load Growth, High Temperatures Expected to Strain Grid This Summer

WASHINGTON, D.C. – Load growth is expected to drive higher peak demand this summer and could strain resources in some areas during certain periods. According to NERC’s 2025 Summer Reliability Assessment, aggregated peak demand is forecast to increase across all 23 assessment areas by 10 GW—more than double the increase from 2023 to 2024. New data centers, electrification, and industrial activity are contributing to higher demand forecasts.

While all areas are projected to have adequate resources for normal summer conditions, above-normal electricity demand, periods of low wind and solar output, and wide-area heat events that disrupt available transfers and generator availability could leave system operators short on supply in at-risk areas, the assessment finds. New resource additions—primarily solar and some batteries—are helping to meet surging load growth. However, these additions are offset by ongoing generator retirements and introduce more complexity and energy limitations into the resource mix.

Full Announcement | 2025 SRA | 2025 SRA Infographic |  2025 SRA Video 

Regardless of how it happens (natural or deliberate), or the scale (local, regional, national), our fragile power grid is the Achilles heel of our nation, and our economy.   

Most disasters boil down to unscheduled camping - for days, or sometimes weeks - in your home, in a community shelter, or possibly even in your backyard.  

 My `standard advice' is that everyone should strive to have the ability to withstand 7 to 10 days without power and water. Recommended preps include:

• A battery operated NWS Emergency Radio to find out what was going on, and to get vital instructions from emergency officials
• A decent first-aid kit, so that you can treat injuries
• Enough non-perishable food and water on hand to feed and hydrate your family (including pets) for the duration
• A way to provide light when the grid is down.
• A way to cook safely without electricity
• A way to purify or filter water
• A way to handle basic sanitation and waste disposal. 
• A way to stay cool (fans) or warm when the power is out.
• A small supply of cash to use in case credit/debit machines are not working
• An emergency plan, including meeting places, emergency out-of-state contact numbers, a disaster buddy, and in case you must evacuate, a bug-out bag
• Spare supply of essential prescription medicines that you or your family may need
• A way to entertain yourself, or your kids, during a prolonged blackout

Some of my preparedness blogs on how to become better prepared in case the lights go out include:

 #NatlPrep: Prolonged Grid Down Preparedness

Post-Milton Improvements To My Power Preps

The Gift of Preparedness 2024

Being prepared for prolonged power outages doesn't guarantee you and your loved ones will come through a major disaster unscathed.

But it is relatively cheap insurance, and when things go pear-shaped, it can substantially improve your chances. 

EID Journal: Investigation of Influenza A(H5N1) Virus Neutralization by Quadrivalent Seasonal Vaccines, United Kingdom, 2021–2024

Credit ACIP

#18,718

While its fearsome and oft quote 50% case fatality rate (CFR) is probably overstated - inflated due to detection bias, where severe and/or hospitalized patients are more likely to be tested and identified - even a 5% fatal outcome from H5N1 would make it the worst pandemic on record. 

H5N1 also has a reputation for hitting younger adults and children the hardest (see Nature Comms: Immune history shapes human antibody responses to H5N1 influenza viruses).

We can see a similar impact in the 1918 pandemic's infamous `W shaped Epi curve’ (below) which indicates that those in their teens, 20s, and 30s were particularly hard hit by that H1N1 virus.

Given the challenges of quickly bringing a safe, and effective, H5N1 vaccine to the masses (see SCI AM - A Bird Flu Vaccine Might Come Too Late to Save Us from H5N1), there is understandably a lot of interest in how much preexisting immunity there might be in the community due to prior influenza exposures or seasonal vaccinations. 

It's not a new idea.  In 2007's Seasonal Vaccine May Provide Small Protection Against Bird Flu we looked at two reports suggesting some (small) amount of cross-protection might be afforded by the seasonal flu shot.  

More recently, it has been suggested that repeated receipt of the seasonal flu shot might provide some small degree of protection, due to the similarity of the H1N1 and H5N1 NA gene segment (see EID Journal: A(H5N1) NA Inhibition Antibodies in Healthy Adults after Exposure to Influenza A(H1N1)pdm09).

Last summer, however, in CDC A(H5N1) Update: Population Immunity to A(H5N1) clade 2.3.3.4b Viruses, the CDC reported finding extremely low to no population immunity, even among those who recently received a seasonal flu vaccine. 

Throughout the fall and winter we continued to see preprints and studies - albeit using different methods and materials (see below) - keeping the idea alive. 

Preprint: Pre-existing H1N1 Immunity Reduces Severe Disease with Cattle H5N1 Influenza Virus

Preprint: Targets of influenza Human T cell Response are Mostly Conserved in H5N1

Two More Preprints Suggesting Prior H1N1 Infection May Provide Some Cross-Protection Against `Bovine' HPAI H5N1

Two EID Journal Articles On Prior Immunity From A(H1N1)pdm09 Infection Against H5N1 (in Ferrets)

While today's study may not be the last word on the subject, researchers in the UK found:

• While QIVs significantly boosted neutralizing antibodies against seasonal A(H1N1), they detected little to no neutralizing antibody response against the two H5N1 strains

• Most participants (all age < 59) had no detectable neutralizing titers against the Texas H5N1 strain, and only a few had low-level titers for the Cambodia strain.

• No evidence that QIV vaccination provided a boost in cross-reactive immunity to H5N1

I've reproduced the link, abstract, and some excerpts from the study, but you'll want to read it in its entirety.  I'll have a postscript after the break. 

Dispatch

Investigation of Influenza A(H5N1) Virus Neutralization by Quadrivalent Seasonal Vaccines, United Kingdom, 2021–2024

Phoebe Stevenson-Leggett1, Lorin Adams1, David Greenwood1, Abi Lofts, Vincenzo Libri, Bryan Williams, Sonia Gandhi, Charles Swanton, Steve Gamblin, Edward J. Carr1, Ruth Harvey1, Nicola S. Lewis1, Mary Y. Wu, Emma C. Wall

Abstract

We tested cross-neutralization against highly pathogenic avian influenza A(H5N1) virus in adults vaccinated with 2021–2023 seasonal quadrivalent influenza vaccine in the United Kingdom. Seasonal quadrivalent influenza vaccines are unlikely to protect vulnerable persons against severe H5N1 disease during widespread transmission. Enhanced measures are needed to protect vulnerable people from H5N1 virus infection.

(SNIP)

The Study

We compared humoral neutralization of 2 H5N1 viruses, A/dairy_cattle/Texas/24-008749-002/2024 (2.3.4.4b) and A/Cambodia/NPH230776/2023 (2.3.2.1c), in serum samples alongside a seasonal influenza A(H1N1) virus isolate, A/Wisconsin/67/2022, before and after QIV in participants from the University College London Hospitals–Francis Crick Institute Legacy study cohort (https://clinicaltrials.gov/study/NCT04750356External Link) (Appendix Figure). 

The study included 61 adults (median age 49 [range 38–58] years); 44 (72%) were women, and 17 (28%) were men. Thirty (49%) adults were vaccinated in only the 2021–22 season, but all 61 were vaccinated in >1 study season (2021–22, 2022–23, and 2023–24). Median sampling duration after vaccine dose for 2021–22 was 81 (interquartile range [IQR] 61–81) days, for 2022–23 was 67 (IQR 38–68) days, and for 2023–24 was 77 (IQR 44–77) days. Twenty-seven (44%) participants reported a single underlying condition (Table).

In line with their effectiveness against seasonal influenza, each QIV generated a statistically significant boost in serum neutralization of A/Wisconsin/67/2022 in each season tested (p = 0.003–0.007 by χ2 test) (Figure). In contrast, HPAI H5 virus neutralization in our cohort of healthy adults was blunted or absent.

In prevaccine serum samples, we detected neutralization above background against A/Cambodia/NPH230776/2023 in a few samples but did not detect any neutralization against A/dairy_cattle/Texas/24-008749-002/2024 isolate (Figure). No seasonal QIV resulted in a cross-neutralization boost against either HPAI H5 virus (Figure).

Ongoing adaptation of HPAI H5N1 clade 2.3.4.4b virus in cows and other mammal hosts found on dairy farms, including rodents and cats, substantially increases the risk for a major HPAI H5N1 virus epidemic or pandemic in humans (2,4). The paucity of human serologic memory against either H5N1 virus strain raises the potential for widespread vulnerability to infection within the adult population. We observed a predictable boost to neutralizing titers against the contemporary seasonal influenza A(H1N1) virus (A/Wisconsin/67/2022) that was absent for the 2 clinically relevant H5N1 viruses tested in our high-throughput neutralization assay (Appendix). Neutralizing antibody titers have long been used as a correlate of protection against seasonal influenza (12); thus, our observations suggest seasonal QIVs are unlikely to offer adequate serologic protection against H5N1 virus.

Immunity against influenza evolves throughout the lifespan, and early infection exposures influence subsequent antibody responses after infection and vaccination (13). Few participants in our study had detectable neutralizing titers above background to the 2.3.2.1c A/Cambodia/NPH230776/2023 virus and none to the 2.3.4.4b A/dairy_cattle/Texas/24-008749-002/2024 virus. Together with our observed lack of QIV boosting, our results suggest that strategies reliant on existing population-level or QIV-based immunity against H5N1 virus infection must be approached with caution.

One limitation of this study is the lack of in vivo challenge to test for cross-protection. Some studies have reported transient protection against H5N1 challenge after transferring QIV-vaccinated human serum to mice, which was not accurately predicted by in vitro assays, including virus neutralization assays (14,15). Cross-neutralization might also occur in the absence of nAbs, but without in vivo testing, we cannot conclusively determine the extent to which the QIV might provide protection against H5N1 virus. A second limitation is that our cohort, predominately working age, healthy adults receiving occupational QIV, do not represent a population at high risk for severe influenza disease and death.

However, they represent an immunocompetent population and would be expected to have the most robust detectable immunity. Third, although we tested 2 H5N1 viruses associated with recent human disease, despite extensive efforts, we could not eliminate background signal in our assay. Thus, we were unable to fully quantify neutralization at lower titers and opted to describe the range within which we detected background signal.

As of 2025, no neutralization titers were available from postinfection serum samples in dairy farm workers to further refine that cutoff (6). Further investigation is required to address the issue of background signal. However, other studies suggest nonspecific inhibition by human serum as a possible explanation for low-level readouts for protection (15).

Finally, our use of whole virus to assess nAb titers did not allow determination of the extent to which hemagglutinin- or neuraminidase-specific antibodies might have contributed to overall neutralization. However, the high-throughput live-virus neutralization we describe (Appendix) is a highly valuable tool for pandemic preparedness, offering a method for near real-time analysis of serum-based immunity to emerging viruses in large cohorts.

Conclusions

The effectiveness of QIV against influenza A(H5N1) virus remains uncertain, and clarification on the extent of cross-protection in humans is urgently needed. Considering that uncertainty, timely and effective deployment of targeted vaccines would be crucial during widespread influenza A(H5N1) outbreaks. To reduce risks for severe illness and death requires enhanced measures that mitigate the spread of HPAI H5N1 viruses to humans, accelerated pipelines for H5-directed influenza vaccines, and systems that rapidly and equitably reach clinically vulnerable persons worldwide (2).

Dr. Stevenson-Leggett is a specialist COVID Unit postdoctoral researcher at the Francis Crick Institute. Her research interests include high-throughput, live virus neutralization. Mr. Adams is a PhD student within the World Health Organization’s Worldwide Influenza Centre. His research interests include in vitro pathogenicity assessment of influenza viruses, including H5N1 strains.

The exclusion of those over the age of 58 from this study is undoubtedly due to the fact that those born prior to 1968 were likely first exposed to H2N2 or H1N1 influenza (both HA Group 1 viruses), and may have some small degree of preexisting immunity to the H5N1 virus (see Science: Protection Against Novel Flu Subtypes Via Childhood HA Imprinting).

While this advantage is thought to be small, and is likely offset by increasing comorbidities among this older cohort, it might be enough to skew the results. 

There are still good reasons to get the seasonal flu vaccine, prior to - and even during - an H5Nx pandemic.  

1. It still may provide some small boost to your immune response.  Neutralizing antibodies aren't the only immune defense against infection. 
2. It could help prevent a co-infection with H5N1 and seasonal flu, which has the potential for being more severe - or worse - generating a reassorted virus (see  Preprint: Intelligent Prediction & Biological Validation of the High Reassortment Potential of Avian H5N1 and Human H3N2 Influenza Viruses).

We've also seen cautionary reports (see St. Jude Researchers: Current Antivirals Likely Less Effective Against Severe Infection Caused by Bird Flu in Cows’ Milk), suggesting our antiviral armamentarium may be inadequate for dealing with an H5 pandemic. 

Although there may be other treatments developed in the opening months of a pandemic (mAbs, convalescent serum, etc.), our first line of defense in the next pandemic will - once again - rely heavily on NPIs (non-pharmaceutical interventions),

Things like face masks, hand washing, ventilation, staying home while sick, and avoiding crowds.

Which is why I'm recommending that people consider now (see A Personal Pre-Pandemic Plan) what they will do when the next global health crises emerges.