Preprint: Antibodies elicited by the 2025-2026 influenza vaccine in humans

CDC FluView Week 52

 #19,013

While reporting of flu activity is probably still lagging due to the holidays, later today we should get the latest CDC FluView report on what - by all accounts - is shaping up to be a brutal seasonal flu season (see map above).

The subclade K H3N2 virus we began tracking more than 2 months ago (see Increasing Concerns Over A `Drifted' H3N2 Virus This Flu Season) continues to plague Australia long after their flu season should have ended, and has now become dominant in the Northern Hemisphere. 

Despite significant antigenic changes in this `drifted' subclade K, we've seen early indications that this year's vaccine may not be a total `miss', and is still worth getting (see UKHSA Preprint: Early Influenza Virus Characterisation and Vaccine Effectiveness in England in Autumn 2025, A Period Dominated by Influenza A(H3N2) Subclade K).

When I got my flu shot in October I already had a strong inkling that the H3N2 component was going to be `suboptimal', as the WHO had already changed the formulations for next year's Southern Hemisphere flu shot.

Still, some protection is better than no protection, and so I gladly rolled up my sleeve.  

Yesterday a new preprint appeared from Scott Hensley and others at the University of Pennsylvania, which further characterizes this year's vaccine match, conducting  serological testing (hemagglutination inhibition (HAI) assays) on blood samples from 76 adults taken before - and about a month after - vaccination

While they report reduced antibody titers compared to the vaccine strain, they found the vaccine was likely `somewhat effective' against subclade K, and still worth getting. 

After vaccination, about 70% had antibody levels usually associated with protection against the vaccine strain (J.2), while nearly 40% reached that level for the subclade K virus.

As with all studies, there are some limitations worth noting, including.

• Only 1 vaccine formulation (standard dose egg-based 2025-2026 Flulaval Trivalent influenza vaccine) was tested
• Challenge was limited to 1 strain of the subclade K virus (A/New York/GKISBBBG87773/2025)
• Follow-up sera collection was 27-30 days post-vaccination, telling us relatively little about the duration of protection.  

How all this plays out in terms of real-world protection (against both infection, and severe disease) won't be fully known until after the flu season has ended, but these are fairly encouraging results.

First the link, and a few excerpts from, the preprint.  I'll return with more after the break. 

Antibodies elicited by the 2025-2026 influenza vaccine in humans
Jiaojiao Liu, Shuk Hang Li, Naiqing Ye, Tachianna Griffiths, Elizabeth M Drapeau, Reilly K. Atkinson, Ronald G. Collman, Scott E. Hensley

doi: https://doi.org/10.64898/2026.01.05.26343449
This article is a preprint and has not been certified by peer review

Abstract

A new H3N2 variant (named subclade K) possesses several key hemagglutinin substitutions and is circulating widely during the 2025-2026 influenza season. In this report, we completed experiments to determine if the 2025-2026 seasonal influenza vaccine elicits antibodies in humans that recognize this variant.

We find that H3N2 subclade K viruses are antigenically advanced; however, the 2025-2026 seasonal influenza vaccine elicited antibodies in many individuals that efficiently recognized these viruses.

Thus, the current seasonal influenza vaccine will likely be somewhat effective at preventing H3N2 subclade K virus infections.

       (SNIP)

Conclusions 

Collectively, our data suggest that H3N2 subclade K viruses are antigenically advanced compared to the 2025-2026 H3N2 vaccine strain; however, the antigenic differences that we observed in sera from some humans are not as large as previously reported in ferrets2 .

While we find that human antibodies elicited by vaccination react more efficiently to the H3N2 vaccine strain relative to subclade K H3N2 viruses, we found that many individuals produced antibodies that efficiently recognized subclade K H3N2 viruses after vaccination. 

Our study highlights the benefits of receiving influenza vaccinations, even in seasons that include circulation of variant viruses.

        (Continue . . . )

There are other good reasons to get this year's flu shot, if you haven't done so already

• It is always possible we could see an extended flu season, much like Australia has reported;  one that lingers on into April or May. 

• Even if  H3N2 begins to wane in the weeks ahead, we could see a late season surge in H1N1 or Influenza B.

• And with increasing levels of  HPAI H5 in the environment, there is (a likely small) potential for a co-infection with H5 and seasonal flu to produce a pandemic strain (see Preprint: Intelligent Prediction & Biological Validation of the High Reassortment Potential of Avian H5N1 and Human H3N2 Influenza Viruses).

Antigenic `Shift' or Reassortment

While rare, this isn't just a theoretical concern; twice in my lifetime (1957 & 1968) avian flu viruses did precisely that; reassorted with a seasonal flu virus and launched a human pandemic.

• The first (1957) was H2N2, which according to the CDC `. . . was comprised of three different genes from an H2N2 virus that originated from an avian influenza A virus, including the H2 hemagglutinin and the N2 neuraminidase genes.'

• In 1968 an avian H3N2 virus emerged (a reassortment of 2 genes from a low path avian influenza H3 virus, and 6 genes from H2N2) which supplanted H2N2 - killed more than a million people during its first year - and continues to spark yearly epidemics more than 50 years later.

While increased uptake of the flu vaccine isn't guaranteed to prevent another reassortment event, it should reduce the chances. 

As would taking other steps to prevent infection; such as wearing masks in crowded indoor areas, using hand sanitizer, and staying home when you are sick. 

Or we can do nothing, and take our chances. 

Nature Comms: Adjuvanted Influenza Vaccination Increases Pre-existing H5N1 Cross-reactive Antibodies

 

#19,012

Despite the initial CDC assessment (see July 14th, 2024 H5N1 Update) that `. . . that there is extremely low to no population immunity to clade 2.3.4.4b A(H5N1) viruses in the United States', we seen studies suggesting there may be some limited immunity; particularly in those born before 1968. 

A few recent examples include:

mBio: Low levels of influenza H5N1 HA and NA antibodies in the human population are boosted by seasonal H1N1 infection but not by H3N2 infection or influenza vaccination

Preprint: Cross-Reactive Human Antibody Responses to H5N1 Influenza Virus Neuraminidase are Shaped by Immune History

Preprint: Neuraminidase Imprinting and the Age-related Risk of Zoonotic Influenza 

Simply put, the first influenza virus you are exposed to (HA Group 1 or 2) is believed to affect your immune response for the rest of your life (see Nature: Declan Butler On How Your First Bout Of Flu Leaves A Lasting Impression). 

How much real-world protection early or past H1/H2 exposure might offer against H5Nx - or how long it might last - are unknown, but it has been suggested it might provide an `edge' against severe disease.

 

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 potential stop-gap measures that might help blunt the opening months of a pandemic.

So far, boosting with existing H1N1 vaccines has shown very limited value (see EID Journal: Investigation of Influenza A(H5N1) Virus Neutralization by Quadrivalent Seasonal Vaccines, United Kingdom, 2021–2024).

But today we have a study which suggests using an interesting - but potentially controversial - option; deploying a standalone booster ASO3 adjuvanted H1N1 vaccine, similar to the one used in Europe during the 2009 pandemic. 

Given its highly publicized link to an increased incidence of narcolepsy - particularly in children and adolescents (see Finland: Task Force Report On Pandemrix-Narcolepsy Link) - an ASO3 adjuvanted vaccine would likely face stiff headwinds from an already vaccine-hesitant society. 

First, a link, and the abstract to the study - which contains some surprises - after which we'll take a deeper look into their findings. 

Adjuvanted influenza vaccination increases pre-existing H5N1 cross-reactive antibodies 

Mariana Alcocer Bonifaz, Disha Bhavsar, Claire-Anne Siegrist, Arnaud Didierlaurent & Benjamin Meyer
Published: 07 January 2026article number , (2026)

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 Abstract

Highly pathogenic H5N1 avian influenza viruses of clade 2.3.4.4b cause sporadic human infections and currently raise concerns about a new influenza pandemic. Heterogeneities in disease severity have been observed in the past and are reported among infected farm workers in the United States. These may be attributed to differences in pre-existing H5N1 cross-reactive antibodies. 

In this study, we characterize H5N1 cross-reactive antibody landscapes in the current population (#NCT05794412 and #NCT01022905) and assess the effect of AS03-adjuvanted pandemic H1N1 and non-adjuvanted seasonal influenza vaccination on H5N1 cross-neutralizing and IgG antibody titers targeting a range of influenza virus-derived antigens. We detect H5N1 cross-neutralizing antibodies using a vesicular stomatitis virus-based pseudovirus system that correlate well with antibodies inhibiting the spread of authentic H5N1 viruses, anti-group 1 hemagglutinin stalk and anti-trimeric hemagglutinin antibodies.

Additionally, we find that AS03-adjuvanted pandemic H1N1 vaccination increases H5N1 cross-reactive antibodies significantly in a pandemic H1N1 immunologically partially naïve population. Furthermore, we show that immune imprinting causes distinct H5N1 cross-reactive antibody patterns pre-vaccination.

(SNIP)

In conclusion, we could show that low levels of H5N1 cross-neutralizing antibodies exist in the population in 2009 and more recently in 2023. Low dose AS03-adjuvanted pandemic H1N1 vaccination was able to substantially induce H5N1 cross-reactive antibodies and could overcome the effect of immune imprinting on H5N1 cross-reactive antibody patterns in a pH1N1 immunologically partially naïve population.  

       (Continue . . . )

In a nutshell, the authors report:

• Most adults carry weak antibodies against today's H5N1 bird flu from past human flu infections or vaccines, which may reduce the severity of infection.

• A low-dose AS03 adjuvanted H1N1 vaccine increases these antibodies nearly 4-fold -  compared to just 30% from the standard seasonal flu shot.

• This effect would likely be of greatest benefit to those exposed to HA Group 2 viruses (H3N2) early in life, as HA Group 1 subjects saw less impact.

• In a bit of a twist, receipt of the regular seasonal flu shot within a few weeks of the booster actually dampened its effect. 

While there is no mention of the past safety concerns over ASO3 in this paper, it would clearly be a factor in any adoption of this strategy. Absolute risk was deemed low 15 years ago, and varied by geographic regions, but the EMA Recommended Restrictions On Use of Pandemrix Vaccine in those under the age of 20 in 2011.

It would be of interest to know if other adjuvants - like MF59 (widely used in Europe) - would produce similar gains.  But in a severe enough pandemic, even an AS03 vaccine might be an attractive option. 

As we've discussed previously (see Manufacturing Pandemic Flu Vaccines: Easier Said Than Done), producing and delivering billions of doses of a safe and effective H5 vaccine is a tall order, and success is not guaranteed. 

We've also seen warnings that our current influenza antivirals may be lacking (see St. Jude Researchers: Current Antivirals Likely Less Effective Against Severe Infection Caused by Bird Flu in Cows’ Milk) along with signs of growing antiviral resistance in avian flu (see Emerg. Microbes & Inf: Oseltamivir Resistant H5N1 (Genotype D1.1) found On 8 Canadian Poultry Farms).

Add in the growing anti-science bias of the public, often fueled by AI generated clickbait videos and political rhetoric, even a low CFR H5 pandemic could be disastrous.  

While I could certainly do without another pandemic in my lifetime, nature's laboratory may have other plans. 

Which why we need to explore a wide range of options now, before we desperately need them. 

PNAS: Reconstructing the Early Spatial Spread of Pandemic Respiratory Viruses in the United States

 
#19,011

Long-time readers are aware of my limited grasp of statistics, and probably suspect I'll drown someday trying to ford a stream that is - on average - 2 feet deep. Which is why I won't even try to dissect the advanced methods used in today's study from Columbia University's Mailman School of Public Health. 

But their findings; that early cryptic spread of pandemic viruses are hard to predict - even when viewed in retrospect - is worthy of deeper discussion.

First, in broad strokes, a brief summary from the press release.

News Release 5-Jan-2026
Study examines how the last two respiratory pandemics rapidly spread through cities
Peer-Reviewed Publication

Columbia University's Mailman School of Public Health
The researchers set out understand the geographic spread of the two pandemics to inform strategies to prevent future pandemics. They applied detailed data on the dynamics of the two infectious diseases to a computer model to simulate their spread using known patterns of air travel and commuting, as well as potential superspreading events. They focused on over three hundred metropolitan areas in the U.S.

In the simulations, both pandemics were widely circulating in most of the metro areas within weeks, before government interventions or early case detection. While the specific transmission pathways across locations were different for the last two pandemics, the spatial expansion was driven by several shared transmission hubs such as the New York and Atlanta metropolitan areas. Their spread was largely driven by air travel rather than commuting, though random dynamics introduced substantial uncertainty in transmission routes, which makes it hard to predict where the outbreaks will happen in real time.

        (SNIP)

Beyond reconstructing the historical spread of the last two pandemics, the study also provides a generalizable framework to infer early epidemic dynamics that may be applied to other pathogens. While mobility, particularly air travel, is a key driver of pandemic spread, the researchers caution that other factors also play a role, including community demographics, school schedules, winter holidays, and weather conditions.

        (Continue . . . )

A link, and some excerpts from the full study, after which we'll look at some of the real-life implications.  

Reconstructing the early spatial spread of pandemic respiratory viruses in the United States
Renquan Zhang, Rui Deng, Sitong Liu , +4 , and Sen Pei  
January 6, 2026
https://doi.org/10.1073/pnas.2518051123
Vol. 123 | No. 2

Abstract

Understanding the geographic spread of emerging respiratory viruses is critical for pandemic preparedness, yet the early spatiotemporal dynamics of the 2009 H1N1 pandemic influenza and severe acute respiratory syndrome coronavirus 2 in the United States remain unclear. 

While mobility and genomic data have revealed important aspects of pandemic spatial spread, several key questions remain: Did the two pandemics follow similar spatial transmission routes? How rapidly did they spread across the United States? What role did stochastic processes play in early spatial transmission?

To address these questions, we integrated high-resolution disease data with a robust, data-efficient inference framework combining air travel, commuting flows, and pathogen superspreading potentials to reconstruct their spatial spread across US metropolitan areas.

The two pandemics exhibited distinct transmission pathways across locations; however, both pandemics established local circulation in most metropolitan areas within weeks, driven by several shared transmission hubs. Early spatial spread was more strongly associated with air travel than with commuting, though stochastic dynamics introduced substantial uncertainty in transmission routes, creating challenges for timely detection and control.

Simulations indicate that broad wastewater surveillance coverage beyond top transmission hubs coupled with effective infection control may slow initial spatial expansion. Our findings highlight the rapid, stochastic spread of pandemic respiratory pathogens and the difficulties of early outbreak containment.

        (Continue . . . )
 

For those who are as statistically challenged as am I; `stochastic' is just a fancy word for "random" or "probabilistic".  We often talk about the R0 (r-naught) of a virus - how many people one person is likely to infect - but that's just an average. 

Some people may get sick, wisely stay home, and infect no one else. Others may mask their symptoms with OTC cold/flu meds and fly to a convention; becoming a superspreader that infects dozens. 

Individual choices - both good and bad - can affect how quickly a pandemic spreads. As can many external factors, like the weather, holidays, community demographics, and school closures. 

And of course, not all viral threats are created equal. 

The SARS-COV virus of 2022-2023 famously did not spread asymptomatically, which made quarantine of symptomatic individuals effective (see SARS and Remembrance), making containment possible. 

H1N1 and COVID, however, could be spread asymptomatically and via aerosols, and that made them virtually unstoppable.   

The reality is, it doesn't take a super virus to spread uncontrollably. Even a (relatively) mild H1N1 virus swept the world in 2009, and supplanted the old H1N1 virus, all in a matter of weeks.

While many countries implemented border closings, passenger screenings, and airport thermal scanners to try stop H1N1 and COVID; at best they only delayed entry by a matter of days or weeks.   

Most viruses take days - up to a week or longer - to incubate. And with 7 million airline passengers each day, any attempts to identify and isolate infected passengers are probably doomed from the start.

Today's study is a reminder that once a respiratory pandemic virus is transmitting efficiently in the community, our ability to stop it is laughably small. 

The authors of today's study do suggest airport wastewater surveillance at key transmission hubs (testing sewage from aircraft, airport terminals, and related infrastructure) would be a cost effective early warning system. 

This would not only pick up asymptomatic carriers, or tell us where to deploy medical assets, it might even alert us to emerging threats before they become fully transmissible.

As much merit as that idea has - given our current level of pandemic denial, and unwillingness to test and share data -  I'm not particularly hopeful.

Arch. Pub. Health: Excess Primary Healthcare Consultations in Norway in 2024 Compared to Pre-COVID-19-pandemic Baseline Trends

#19,010

From very early on in the SARS-CoV-2 pandemic, we saw concerns raised over the potential long-term impact of COVID infection; often centered around cardiac or neurological involvement.

In early April 2020, the New York Fire Department reported a 400% increase in sudden cardiac arrest death calls beginning in late March (see NBC affiliate Massive Spike in NYC ‘Cardiac Arrest’ Deaths Seen as Sign of COVID-19 Under counting).

In June, JAMA published an original investigation which found a huge increase in out-of-hospital cardiac arrests in New York City during the peak of their COVID-19 epidemic, writing:

From March 1 to April 25, 2020, New York City, New York (NYC), reported 17 118 COVID-19–related deaths. On April 6, 2020, out-of-hospital cardiac arrests peaked at 305 cases, nearly a 10-fold increase from the prior year.

Admittedly, most of these cases were never tested for COVID-19, making any link circumstantial. The following month, however, in JAMA: Two Studies Linking SARS-CoV-2 Infection To Cardiac Injury, we saw physical evidence of cardiac injury due to COVID infection, even among a relatively young cohort of previously healthy adults.

By mid-summer, it was becoming apparent that COVID was far more than just an acute respiratory infection (see Nature Med. Review: Extrapulmonary manifestations of COVID-19), and could produce blot clots, along with neurological, renal, and cardiovascular damage.

 In late July we saw this cautionary editorial published in JAMA.

Coronavirus Disease 2019 (COVID-19) and the Heart—Is Heart Failure the Next Chapter?
Clyde W. Yancy, MD, MSc1,2; Gregg C. Fonarow, MD3,4
JAMA Cardiol. Published online July 27, 2020. doi:10.1001/jamacardio.2020.3575

Since then, studies showing post-acute impacts of COVID infection have exploded, with many citing repeated COVID infections as increasing the risk of long-term health damage. A few (of many) include:

Nature: Long-term Cardiovascular Outcomes of COVID-19

AHA: COVID-19 May Trigger New-Onset High Blood Pressure

NIH: Study Shows SARS-CoV-2 Infects Coronary Arteries, Increases Plaque Inflammation

EHJ: Accelerated Vascular Ageing After COVID-19 Infection: The CARTESIAN Study

Terms like `Long COVID' and PASC (Postacute Sequelae of COVID) are now officially recognized, but their impact remains poorly quantified (and often disputed).

Much of the evidence is anecdotal, or inferential, because 90% of the world stopped testing, and reporting on ICU admissions and deaths, more than 3 years ago (No News Is . . . Now Commonplace).

The world desperately wanted to move on from COVID, and it decided the best way to do so was by touching up the X-rays.  But of course, the health burden of COVID - recognized or not - remains. 

Today we've a study from the Norwegian Institute of Public Health and others, that looks at the trajectory of primary care consultations in Norway both before - during - and after the COVID pandemic.

What they found was the number of consultations in 2024 were about 7% above pre‑pandemic expectations (see graphic at top of this blog). Most of these were coded as being for respiratory, fatigue, psychological, cognitive, and some infectious/gastrointestinal complaints.

Patterns that have often been associated with PASC or `Long COVID', but remain exceedingly difficult to establish a causal link.  

The authors - who cite (and are critical of) Norway’s national COVID strategy which `. . . emphasizes the assumed benefits of sustaining population immunity through repeated SARS-CoV-2 infections' - hypothesize that repeated COVID infections have led to population‑level health impacts, with PASC and post‑COVID immune dysfunction driving much of the cited excess primary care consultations.

The authors note, in particular, the impact this has had on women, children, adolescents, and young adults.

I've reproduced the abstract below, but you'll want to follow the link and read the full article.  I'll have a brief postscript when you return.

Excess primary healthcare consultations in Norway in 2024 compared to pre-COVID-19-pandemic baseline trends

Research
Open access
Published: 02 January 2026
article number , (2026)

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We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Abstract

Background

The risk of post-acute sequelae of COVID-19 (PASC) is estimated at 3–6% per infection in 2024. We hypothesized that widespread SARS-CoV-2 infections could lead to population-level consequences. Our previous study identified substantial increases in Norwegian primary healthcare consultations in 2023—compared to pre-pandemic levels—for conditions associated with acute COVID-19 and PASC. This study extended that analysis to 2024. We then assessed whether observed patterns were compatible with our hypothesis.

Methods

We used data from the Norwegian Syndromic Surveillance System, which captures nationwide primary healthcare consultations for 102 ICPC-2 codes (out of a possible 710) that are relevant for infectious disease surveillance and some post-acute infection syndromes. Bayesian linear regression models were fitted to 2010–2019 trends, adjusting for population changes, to estimate expected values for 2024. Excess consultations were calculated by age and sex. A COVID-19 community spread was proxied by vaccination-adjusted weekly hospitalization rates.

Results

In 2024, there were 17,800,365 consultations, corresponding to an absolute excess of 1,185,231 consultations, or a 7.1% relative excess, compared to the modelled baseline. The 10 code combinations with largest absolute excess in 2024 were respiratory infections (325,726 excess consultations; 20% relative excess), fatigue (205,381; 70%), psychological symptom/complaint other (188,978; 87%), acute stress reaction (182,079; 76%), feeling depressed (126,783; 133%), hyperkinetic disorder (112,763; 116%), abdominal pain/cramps general (84,544; 29%), memory disturbance (39,177; 63%), conjunctivitis (34,643; 59%), and infectious disease other/NOS (33,556; 81%). COVID-19 community spread showed the strongest correlations with conjunctivitis, strep throat, respiratory infections as a group (R**), fatigue, infectious disease other, memory disturbances, and pneumonia. Deviations from pre-pandemic trends varied: respiratory and psychological disorders worsened from 2020 onward and several conditions showed dramatic excess from 2022–2024. Females 15–29, children, adolescents, and young adults had disproportionately large relative excesses for consultations for memory disturbances.

Conclusions

Primary healthcare consultations in 2024 significantly exceeded pre-pandemic expectations, especially for conditions linked to acute COVID-19 and PASC, though the two cannot be differentiated in these data. While other factors undoubtedly also play a role, findings are compatible with ongoing population-level health impacts associated with repeated SARS-CoV-2 infections, particularly among women, children, adolescents, and young adults. These results emerged under a national COVID-19 strategy that does not account for post-acute consequences of SARS-CoV-2 infection.

(Continue . . . )

The author's hypothesis, and findings, certainly resonate with what I've seen, and written extensively about, for the past 6 years. But proving causality is always difficult, even when the patterns neatly `fit' the hypothesis. 

A task that is made even more onerous by the deliberate dismantling of COVID surveillance, testing, and reporting around the world.  

Society has used this lack of data to trivialize COVID infection (and reinfection) to the point that vaccine uptake has plummeted, and mask-wearing - and other protective measures - have become anathema. 

Meanwhile, COVID continues to exact a heavy toll, while the public remains oblivious to - or highly skeptical of - other threats that may be in the pipeline. 

While ignorance may yield temporary bliss, we risk a very rude awakening down the road. 

South Korea MAFRA: Special Quarantine Measures Implemented for one Month to Prevent the Spread of HPAI

19,009

Like many other countries, this fall South Korea has been hit particularly hard by this fall's return of avian flu, and over the past 30 days we've seen 3 major declarations from MAFRA and local authorities regarding their response. 

South Korea: MAFRA Reports Increased Infectivity & Pathogenicity of This Year's Avian Flu Strains

South Korean City (Naju) Orders Extraordinary Emergency Measures Due to HPAI

South Korea: MAFRA Identifies Biosecurity Breaches On HPAI Infected Poultry Farms

While South Korea has dealt with avian flu off and on for 2 decades - including the disastrous arrival of H5N8 in early 2014 - this year they have been unusually wary; with their CDC holding a 19-day Nationwide, Mock-Training Exercise to Prepare for Zoonotic Influenza in early September.

Six weeks ago, South Korea's MAFRA Ordered Strengthened Quarantine Measures After 3 HPAI H5 Subtypes (H5N1, H5N6, H5N9) Detected In Wild Birds, and last month they announced a 10-fold increase in infectivity of this year's returning virus. 

While we've seen strong responses by South Korea to HPAI outbreaks in the past,  today MAFRA has announced unusually stringent nationwide quarantine and biosecurity measures; even for them. 

Few countries have been as open about their concerns over - and their response to - HPAI, and so other governments, agencies, and poultry producers may want to take note. 

First, the translated announcement, after which I'll have a brief postscript on a curious aspect to today's announcement.

       (Translation)

Special quarantine measures implemented for one month in January to prevent the spread of highly pathogenic avian influenza.

2026.01.05 15:38:20 Avian Influenza Prevention and Control Division

The Central Disaster and Safety Countermeasures Headquarters for Highly Pathogenic Avian Influenza ( Chief: Minister of Agriculture, Food and Rural Affairs Song Mei - ling , hereinafter referred to as the Central Disaster and Safety Countermeasures Headquarters ) announced that as the risk of additional outbreaks has increased due to the recent increase in the occurrence of highly pathogenic avian influenza (AI), it will hold a quarantine countermeasures meeting chaired by Minister of Agriculture, Food and Rural Affairs Song Mei- ling on Monday , January 5 to review the situation of highly pathogenic avian influenza outbreaks and quarantine measures and further strengthen quarantine management .

1. Situation

This winter ('25/'26 season ) , there have been 30 cases of highly pathogenic avian influenza in poultry farms and 22 cases in wild birds .

* Poultry farm outbreak status ( 30 cases in total ): Gyeonggi 9 cases ( Anseong 3, Paju 1, Hwaseong 2, Pyeongtaek 3), Chungbuk 7 cases ( Goesan 1, Yeongdong 1, Jeungpyeong 1, Jincheon 2, Eumseong 2), Chungnam 5 cases ( Boryeong 1, Cheonan 3, Asan 1), Jeollabuk-do 2 cases ( Gochang 1, Namwon 1), Jeollanam-do 6 cases ( Naju 4, Yeongam 2), Gwangju Metropolitan City 1 case

** Status of wild bird detection ( total 23 cases ): Gyeonggi 1, Chungbuk 1, Chungnam 6, Jeonbuk 4, Jeonnam 4, Gyeongbuk 3, Gyeongnam 1, Busan 1, Gwangju 1, Seoul 1

This winter season, for the first time in Korea , three types of viruses ( serotypes : H5N1, H5N6, H5N9) were detected in wild birds and poultry farms , and in particular, the highly pathogenic avian influenza virus ( serotype H5N1) confirmed in Korea this winter season was confirmed to be more than 10 times more infectious than in previous years, making the situation very serious with a higher risk of additional outbreaks than ever before .

As seen in the past when the most cases occurred in December and January , the number of cases of highly pathogenic avian influenza has been increasing since December during this winter season as well , and the cases are particularly concentrated in the Gyeonggi , Chungcheong , and Jeolla regions where chicken and duck are raised. In order to minimize damage, all poultry farms and related personnel must be on alert and implement more thorough quarantine management than before, such as entry control and disinfection .

* Monthly occurrence : (September ) 1 case → (October ) 1 case → (November ) 4 cases → (December ) 22 cases → ( January '26 ) 2 cases

* Occurrence by region : 9 cases in Gyeonggi , 12 cases in South and North Chungcheong , 8 cases in South and North Jeolla , 1 case in Gwangju Metropolitan City

2. Special quarantine measures

The Central Disaster and Safety Countermeasures Headquarters will strengthen quarantine measures as follows to prevent and control highly pathogenic avian influenza .

First , as a special measure to prevent further outbreaks of laying hens, dedicated officers will be assigned to laying hens nationwide (539 farms with over 50,000 hens ) for two weeks from January 5 to January 16 to control the entry of livestock vehicles into the farms and conduct intensive inspections for any violations of quarantine regulations.

* ① Register the number and company of pre-risk livestock vehicles ( eggs , feed , manure ) , control the entry of other vehicles , ② On-site inspection when registered vehicles enter and exit , ③ Instruct and inform drivers of registered vehicles and related companies on quarantine rules

Second , the Avian Influenza Special Quarantine Team and the Ministry of Agriculture, Food and Rural Affairs field response team ( section chief level, etc. ) will be dispatched simultaneously to three risk areas and 11 regions where there is concern about additional outbreaks to conduct quarantine management, including special inspections .

* 3 special quarantine areas : Gyeonggi ( Hwaseong , Pyeongtaek , Anseong ) , South Chungcheong ( Cheonan , Asan ) , North Chungcheong ( Eumseong , Jincheon )

* Field response team 11 risk areas : Gyeonggi Pyeongtaek and Anseong , Chungcheongnam-do Cheonan , Chungcheongbuk - do Eumseong , Jincheon and Cheongju , Sejong , Jeollabuk -do Buan and Gimje , Jeollanam -do Yeongam and Naju

Third , to eliminate sources of contamination inside and outside poultry farms , livestock facilities, and vehicles, the period until January 14, 2026 will be designated as a “ National Intensive Disinfection Week ,” and roads around migratory bird arrival areas and nearby poultry farms will be disinfected at least twice a day .

Fourth , to strengthen disinfection and prevent transmission through vehicles, we will strengthen management by conducting surprise environmental inspections on high-risk livestock vehicles ( egg and feed transport , manure disposal ) entering and exiting poultry farms nationwide from January 5 to January 16 .

* Collect samples from disinfection facilities (222 locations , 1,100 cases ) and conduct detailed tests.

Fifth , we plan to conduct a comprehensive quarantine strengthening campaign in January in cooperation with producer groups . Poultry farms will be divided into three color-coded quarantine zones , and staff will change into colored boots for each zone and conduct intensive disinfection and rat catching operations .

* Promotion of changing boots when moving from the farm yard - polluted area ( red boots ) ↔ inside the anteroom - buffer area ( yellow boots ) ↔ inside the barn - clean area ( blue boots ) in laying hen farms

Sixth, in order to raise awareness and encourage autonomous quarantine in poultry farms, a special inspection and publicity week ('25.12. 31~'26.1. 13) will be designated for poultry farms nationwide, where daily inspections and guidance and education on key quarantine rules will be intensively provided , and quarantine rules will be delivered to farms within the jurisdiction every week through communication channels of city /county ( director in charge ) .

In addition, we will provide guidance and education on quarantine rules tailored to the language of each country for foreign workers working on poultry farms , and further strengthen publicity through the broadcast of disaster warnings to the public.

4. Requests

Minister of Agriculture, Food and Rural Affairs Song Mei-ryeong said , “ This winter, three types of viruses (H5N1, H5N6, H5N9) have been detected in wild birds and poultry farms , and the infectivity of the viruses has been confirmed to be more than 10 times higher than in the past. Therefore, all poultry farm workers and quarantine officials should further strengthen quarantine measures such as controlling the entry and exit of people and vehicles and disinfection, and do their best by mobilizing all available human and material resources . ”

In addition , “ Local governments in Gyeonggi , Chungcheong , and Jeolla regions, where there have been many recent outbreaks , should actively utilize the 1:1 poultry farm manager system through the local disaster response headquarters, which includes quarantine and disaster departments, to prevent the spread to surrounding areas , and intensively inspect quarantine area management and whether poultry farms are following quarantine rules . ”

In addition , he emphasized, “January is the month with the most avian influenza cases following December, so poultry farms should thoroughly follow basic quarantine rules such as controlling the entry of people and vehicles and disinfecting inside and outside the farm with the mindset of protecting their own farm, ” and requested , “ In particular , as there have been many cases in laying hen farms this season , to prevent further outbreaks , disinfection and access control for vehicles transporting eggs and feed, which are major risk factors for transmission , should be doubled or tripled . ”

Aside from ramping up their agency response to 11, there is another glaring change in this latest announcement. Previous statements have focused heavily on farm biosecurity lapses, and repeatedly warned of increased fines and other penalties for future violations. 

Curiously, today's announcement has zero mention of fines or penalties. 

While I'm sure that blatant disregard for biosecurity is still punishable, it is possible (and yes, I'm speculating) that this may be a tacit admission from MAFRA that even high-compliance farms are vulnerable to this year's crop of highly infectious avian flu viruses. 

If that should prove to be the case, then South Korea - and potentially many other countries - could be facing a particularly difficult second half to this year's avian flu season. 

 Stay tuned. 

Referral: JAMA - COVID-19 in Pregnancy Linked With Risk of Neurodevelopmental Disorders in Early Childhood

 

Photo Credit – CDC

#19,008

While we are still in our year-end science `news drought', we do have a release from JAMA, and a link to a new study Obstetrics & Gynecology, which shed new light on the impact of maternal COVID infection on the health of the unborn child. 

This is a topic we've looked at previously, including in 2022's Nature: Deleterious Effects of Nervous System in the Offspring Following Maternal SARS-CoV-2 Infection.  

We've also looked at the impact of maternal influenza (and other viral)  infections on the unborn child, where we've seen similar patterns emerge. A few examples include:

Pregnancy, Influenza & Elevated Psychosis Risks In Adult Offspring

JAMA Psych: Long-term Risk of Neuropsychiatric Disease After Exposure to Infection In Utero

Pregnancy, Influenza & Elevated Psychosis Risks In Adult Offspring

JAMA Psych: Long-term Risk of Neuropsychiatric Disease After Exposure to Infection In Utero

Many researchers believe this is more likely due to Maternal Immune Activation (MIA) - which includes cytokine releases and fever - than to fetal exposure to a specific pathogen. 

In today's report, researchers report that in a study of  > 18 000 live births in the Mass General Brigham health system between March 2020 and May 2021, 861 were exposed to maternal SARS-CoV-2 infection.

When compared to the unexposed cohort, those exposed to COVID-19 in utero had a 29% higher risk of neurodevelopmental delays (e.g. speech or motor issues) by age 3.

Researchers found that males were at higher risk than females, and the risk appeared greatest in those exposed during the third trimester of pregnancy.  

While the results are compelling, this was a single retrospective study; which may have been subject to screening bias and other confounders. Meaning it falls short of proving a `causal connection'.  

That said, its findings do fall in line with other studies we've seen on COVID and other maternal viral infections, and it deserves serious consideration. 

Since neither of these articles appear to be open-access, for copyright reasons I'll just provide the links below for you to follow.  

First up is a plain-language summary published by JAMA at:

COVID-19 in Pregnancy Linked With Risk of Neurodevelopmental Disorders in Early Childhood
Samantha Anderer1

The full research paper can be accessed at:

Neurodevelopmental Outcomes of 3-Year-Old Children Exposed to Maternal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection in Utero

Shook, Lydia L. MD; Castro, Victor MS; Ibanez-Pintor, Laura MD; Perlis, Roy H. MD, MSc; Edlow, Andrea G. MD, MScAuthor Information
Obstetrics & Gynecology 147(1):p 11-20, January 2026. | DOI: 10.1097/AOG.0000000000006112