HK CHP: Another Cryptic Announcement of H9N2 Cases From the Chinese Mainland

 

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While China has never been particularly verbose in the reporting of novel flu cases, until recently we could count on (often, belatedly) learning of the location, onset date, gender, and age of the patient.  

Sometimes they would even characterize the infection as being mild, moderate, or severe. 

Two months ago, in HK CHP: Mainland China Retrospectively Reports 4 More H9N2 Cases, we saw a departure from this format with the announcement (see below) of 4 retrospectively identified cases from last February. 

Details were unusually scant (even for China), with the only identifiers provided being the province, `an individual' and the month.  Last month, Hong Kong's CHP reported 4 more cases in the usual format: 

Not ideal, but more in keeping with what we've come to expect.  Today, however, Hong Kong's CHP is back to reporting new in the barebones format; providing only the month, province, and describing the patient as `an individual'. 

Credit HK CHP - Avian Flu Report Week 51

Often we get clarification from the WHO's periodic Influenza at the human-animal interface report, the latest of which was published yesterday.  Unfortunately, the details are similarly obtuse, reading more like a logic word puzzle than an epidemiological report. 

A(H9N2), China

Since the last risk assessment of 5 November 2025, China notified WHO of four cases of infection with influenza A(H9N2) on 6 November 2025 and three cases on 12 December 2025.

All but two cases were in children. Cases were detected in Guangdong (one), Guangxi (three), Henan(one) and Hubei (two) provinces. The cases had onsets of symptoms in September, October and November 2025. Four cases had reported exposure to backyard poultry, two had exposure to live poultry markets and the source of exposure for one case was under investigation at the time of reporting. 

All cases had mild illness and recovered, except one in an elderly person with underlying conditions who was hospitalized at the time of reporting with severe pneumonia. No further cases were detected among contacts of these cases. A(H9) viruses were detected in environmental samples collected during the investigations around some of the cases.

By combining several other reports, one is able to deduce that 2 of the 3 cases reported today by Hong Kong were likely adults, and one (elderly, with underlying conditions) remains hospitalized with pneumonia.  

But that's about it. 

Sadly, this type of sparse or belated reporting by public health agencies has become increasingly common, and it hasn't been restricted to just China. 

While there are legally binding agreements between nations to report novel flu cases, and other emerging public health threats, the reality is there are no meaningful penalties for non-compliance (see From Here To Impunity).

A week scarcely goes by without the WHO, PAHO, or WOAH reminding member nations to abide by these agreements. In nearly every study we review (see here, here, here, here, and here), the authors desperately call for better surveillance and reporting.

But the political and economic advantages to minimizing - or sanitizing - `bad news' apparently now outweigh any obligation to share scientific information, or inform the public. 

But on the plus side - when the next pandemic threat does emerge - our leaders can truthfully say they never saw it coming. 

Viruses: Replication and Transmission of Influenza A Virus in Farmed Mink

 

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Mink are highly susceptible to both influenza A and SARS-CoV-2 infection, and over the past 16 years we've looked a a number of concerning spillovers, including:

• In 2009's That Touch Of Mink Flu, where at least 11 mink farms in the Holstebro municipality of Denmark were reported to be infected with a variant of the human H3N2 virus.
• Also in 2007, an antigenically distinct H3N2 Swine Influenza was detected in Canadian Mink, reported in a 2009 Journal of Clinical Microbiology study called Characterization of a Canadian Mink H3N2 Influenza A Virus Isolate Genetically Related to Triple Reassortant Swine Influenza Virus.
• A year earlier CIDRAP reported on a European mink found infected with an aggressive form of the H5 flu virus in the Blekinge region of southern Sweden near where H5N1 had been detected in wild birds.
• And even as far back as 1984, a large outbreak in Swedish mink farms was found to be due to the H10N4 avian virus.

Mink are a member of the Mustelidae family of carnivorous mammals, which also includes otters, badgers, weasel, martens, ferrets, and wolverines. Many of these species are susceptible to flu viruses – most notably ferrets – which are often used in influenza research.

Over the past decade we've seen literally dozens of reports of spillovers into mink, including the generation of mink-variant COVID strains which - at least temporarily - circulated in humans in Europe back in 2020 (see Preprint: Emergence & Spread of SARS-CoV-2 Variants from Farmed Mink to Humans and Back - Denmark, June-November 2020).. 

Alarms were raised, again in the fall of 2022 when H5N1 began spreading rapidly through a large mink farm in Spain (see Eurosurveillance: HPAI A(H5N1) Virus Infection in Farmed Minks, Spain, October 2022).

This mink-derived H5N1 virus from Spain carried a rare mutation (PB-T271A), which is believed to `enhance the polymerase activity of influenza A viruses in mammalian host cells and mice'. In 2023 the CDC issued an IRAT Risk Assessment On Mink Variant of Avian H5N1, finding it's scores had risen in 6 of the 10 parameters used to evaluate their zoonotic potential.

Spillovers into farmed animals are particularly worrisome, because they allow for serial transmission across a large number of hosts, which may result in host adaptation.

    

In 2023 we saw scores of fur farms (both mink & fox) in Finland hit by HPAI, resulting in massive culls. 

During that protracted outbreak, in PNAS: Mink Farming Poses Risks for Future Viral Pandemics, we looked at an opinion piece by Professor Wendy Barclay & Tom Peacock on why fur farms - and mink farms in particular - are high risk venues for both flu and SARS.

Since then, new studies have continued to highlight the risks, including last January's Zoonosis & Public Health: Detection of a Reassortant Swine- and Human-Origin H3N2 Influenza A Virus in Farmed Mink in British Columbia, Canada.

All of which brings us to a new study, published 3 days ago in the journal Viruses, which finds that (among a small cohort (n=37) of Chinese farmed mink) past LPAI H9N2 exposure was quite common (89.2%), while they found no detectable antibodies for human H1N1 or avian H3N2, H4N2, H5N1, H6N6, or H11N9.

These pre-exposed mink, however, remained highly susceptible to other influenza A subtypes (only H1N1 and H6N6 were tested), raising  concerns over the ability of mink to serve as `mixing vessels' for influenza reassortment. 

While this study is subject to a number of limitations (cohort size, limited range of viral challenges, etc.), it provides additional evidence on the zoonotic risks of fur-farming; particularly involving mink. 

I've only posted the link, and a few excerpts. Follow the link to read the study in its entirety. 

Replication and Transmission of Influenza A Virus in Farmed Mink

Viruses 2026, 18(1), 9;https://doi.org/10.3390/v18010009 (registering DOI) This article belongs to the Special Issue Surveillance, Prevention, and Treatment of Avian Influenza

 Abstract

Farmed mink are frequently exposed to circulating influenza A viruses (IAVs), as confirmed by viral isolation and serological evidence. Previous work reveals that naïve mink serve as susceptible hosts for both avian and human influenza strains, highlighting their potential role in influenza ecology.

In this study, we investigated whether farmed mink naturally pre-exposed to H9 retain the capacity to serve as “mixing vessels” for reassorting human and avian IAVs. Our results demonstrate that they remain fully susceptible and permissive to infection by both avian H6N6 and human H1N1 influenza strains.

Notably, efficient transmission of these viruses occurred among farmed mink, confirming their potential to sustain viral exchange. These findings indicate that farmed mink represent highly permissive hosts capable of facilitating reassortment between circulating human and avian IAVs.

Given this risk, current mink farming practices may substantially increase the likelihood of a pandemic emergence. We therefore urge immediate revision, stringent enhancement, and rigorous enforcement of biosecurity protocols and active surveillance systems in fur farming operations.

        (SNIP)

4. Discussion

Our study demonstrates that influenza-pre-exposed mink retain their capacity to serve as “mixing vessels” for avian and human influenza A viruses (IAVs), reinforcing the zoonotic risks associated with intensive mink farming.

Despite serological evidence of frequent H9N2 exposure to farmed mink [1,19], these animals remained fully susceptible to heterosubtypic strains, including avian H6N6 and human-origin H1N1 viruses. Both strains replicated efficiently in the respiratory tract and exhibited sustained transmission among pre-exposed mink, confirming their potential to facilitate reassortment between avian and human IAVs.

These findings parallel observations in swine, a well-documented mixing vessel, but highlight a critical gap in biosecurity oversight for mink farming, underscoring their role as underappreciated reservoirs for viral evolution.

        (Continue . . . .)

As we've discussed previously - while the next pandemic virus could certainly emerge directly from the wild - the practice of raising millions of highly (flu & COVID) susceptible animals in densely packed farms unnecessarily raises our pandemic risks. 

While there is a growing movement to ban fur farms - particularly in the EU - Poland and Russia remain major fur producers, as well as the United States and Canada. 

China, however, remains the largest global producer and exporter of farmed fur, accounting for 2/3rds of the world's mink farms. Reportedly fox and raccoon dogs are raised on many of these same farms, increasing the odds of inter-species transmission of novel viruses.

Whether we can summon the political will to take the necessary steps needed to prevent the next pandemic remains to be seen.

But time is definitely not on our side. 

Spain: AEMPS Warns of Counterfeit FLU/COVID Tests Entering European Market

 

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In the midst of what is likely to be the worst flu season in years, Spain's Agencia Española de Medicamentos y Productos Sanitarios (AEMPS) is reporting on a new, and potentially harmful, complication; counterfeit influenza/COVID test kits.  

Counterfeit, or adulterated medicines - or fake diagnostic tests - which are usually purchased online, aren't a new problem.  

In 2013 The Lancet reported that 1/3rd Of Malaria Drugs Are Fake Or Sub-Standard, while two years later - in 2015's The Lancet: WHO Estimates That 50% Of Drugs For Sale Online Are Fake - we looked at a long report on the spectacular growth of fake online prescription drugs. 

In 2020 our own government repeatedly warned of substandard and unsafe PPEs and hand sanitizers flooding the market during the pandemic (see NIOSH & FDA Updates On Counterfeit N95 Respirators & Hand Sanitizers).

Also 5 years ago, in Interpol Warning On Fake/Counterfeit COVID Vaccines, Interpol issued an Orange Notice on the risks of seeing fake, substandard, or possibly even stolen vaccines offered online or even entering the supply chain.

More recently (2023), in response to more than 300 deaths (mostly in children) across 7 countries, we looked at the WHO's 6th Alert On Contaminated Cough Syrup - manufactured primarily in India -which contained dangerous (even fatal) amounts of diethylene glycol (DEG) and /or ethylene glycol (EG) as contaminants.

Over the past 5 years we've seen repeated reports of fake or counterfeit COVID home diagnostic tests being sold in the United States (see FDA statement).  

This week, however, Europe is reporting the arrival of counterfeit combo Flu/COVID home test kits. 

First the translated announcement, after which I'll have a brief postscript.

The Spanish Agency for Medicines and Health Products (AEMPS) reports the detection of counterfeit units of the COVID-19 and Influenza A+B Antigen Combo Rapid Test on the European market.

Publication date: December 19, 2025
Category: Medical devices, counterfeit products
Reference: PS, 65/2025

The manufacturer Safecare Biotech (Hangzhou) Co., Ltd. has confirmed that the products with reference FCO-6032 have been tampered with and that the batch number FCO24090516 is counterfeit.

The Agency establishes a series of recommendations for action aimed at distributors, pharmacies and users

The Spanish Agency for Medicines and Health Products (AEMPS) has been informed, through the competent Portuguese authority, of the marketing in the European market of counterfeit units of the COVID-19 and Influenza A+B Antigen Combo Rapid Test, manufactured by Safecare Biotech (Hangzhou) Co., Ltd., with reference FCO-6032 and batch number FCO24090516.

According to information provided by the competent Portuguese authority, the manufacturer has confirmed that the product has been tampered with and that the batch number FCO24090516 is fake.

Current situation in Spain

The Spanish Agency for Medicines and Health Products (AEMPS) has launched an investigation to determine the distribution of the affected products and the situation in Spain. At this time, it is unknown whether the counterfeit test has been distributed in the country.

However, it is reported that there are compliant units of the self-diagnostic product COVID-19 and Influenza A+B Antigen Combo Rapid Test from the same manufacturer and with reference FCO-6032 on the market, so this information note only affects the counterfeit product.

Affected products

Counterfeit products can be identified by the following:

• A label with altered information regarding the batch number, manufacturing date, and expiration date has been affixed. The counterfeit product details appearing on the label are as follows:
• Batch number: FCO24090516
• Date of manufacture: 09/2024
• Expiration date: 09/2026
• The batch number and expiry date have been removed from the test cassette included in the kit, so only the symbols appear.
• The expiration date has been removed from the tube containing the extraction solution ( buffer ).
• The swab included in the kit is not the same as the one used by the original product manufacturer. The original swab manufacturer is Dalian Rongbang Medical Healthy Devices Co. Ltd., with its authorized representative Lotus NL, BV (Netherlands).

Information for users

• Check if you have the affected product. If so, do not use it.
• Remember that self-diagnostic tests should only be purchased through pharmacies. This ensures the proper origin, storage, and preservation of the test. Furthermore, only through this channel will the user have access to a pharmacist and their advice.

Information for distributors and pharmacies

• Examine your traceability records and check if you have any units of the affected product. If so, do not distribute them, remove them from sale, and inform the Spanish Agency for Medicines and Health Products (AEMPS) at psdivcontrol@aemps.es , indicating the details of the company that supplied you with the product.
• If you are aware of an incident related to the use of these products, please report it to the AEMPS surveillance system.

Admittedly, counterfeit test kits aren't the most egregious example of fake or adulterated medical products (think: watered down antibiotics, fentanyl laced recreational drugs, or cosmetics laced with heavy metals, etc.), but people do rely on their results to make potentially life-or-death decisions. 

While exact numbers are impossible to come by, there are estimates that hundreds of thousands of people are killed each year from fake or adulterated drugs. Serious, albeit non-fatal consequences, are believed even more common. 

In 2024, the WHO published:

Substandard and falsified medical products
3 December 2024  
Key facts

• Substandard and falsified medical products affect people all around the world.
• At least 1 in 10 medicines in low- and middle-income countries are substandard or falsified.
• Countries spend an estimated US$ 30.5 billion per year on substandard and falsified medical products.
• Substandard and falsified medical products are often sold online or in informal markets.

Sadly, with an Internet increasingly filled with dangerously misleading A.I. generated slop, social media influencers who appear willing to tout any product or trend for the `clicks', and well-funded bad actors who continue to manufacture these credible looking products, we've created an environment where it is all too easy to be fooled. 

Caveat Emptor. 

USDA APHIS Reports Wisconsin Dairy Herd Infected With Genotype D1.1

 

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Despite the recent lull in new infected dairy herds reported to the USDA, 5 days ago that agency announced that Wisconsin had Become the 18th State to Detect HPAI H5N1 in Dairy Cattle, after a positive bulk milk sample was detected under the National Milk Testing Strategy testing program.

At the time, only the clade (2.3.4.4b) and subtype (H5N1) were available, with results pending on the genotype. 

Throughout 2024, only genotype B3.13 was detected in cattle, and the USDA worked under the assumption that this was likely the result of a single spillover (in Texas in late 2023) and that the virus was subsequently transported by cattle shipped to other states. 

They believed this to be a `rare', one-off event, sparked by a single rogue genotype, and unlikely to be repeated. A hope that was widely embraced by many other countries, comforted by the lack of spread of B3.13 outside of the United States.

But in July 2024, in Germany: FLI Statement On Experimental Infection Of Dairy Cows With European H5N1 Virus, researchers reported `. . . not only the US isolate but also a recent H5N1 virus from a wild bird in Germany was able to multiply very well in the udder.'

In November of 2024 a different genotype (D1.2) was detected in two pigs on a farm in Oregon, but even bigger news came in February of 2025, when the USDA announced The Occurrence of Another Highly Pathogenic Avian Influenza (HPAI) Spillover from Wild Birds into Dairy Cattle.

This time, it was genotype D1.1, which has emerged the previous fall in wild and migratory birds, and had sparked numerous poultry outbreaks and roughly 2 dozen human infections, some serious (1 fatal). 

Several weeks later a 3rd spillover into cattle was announced by the USDA (see APHIS Statement On HPAI Genotype D.1 In Arizona Dairy Cattle), where they reported:

Whole genome sequencing indicates that this detection is a separate wild-bird introduction of HPAI to dairy cattle, now the third identified spillover event into dairy cattle.

This finding may indicate an increased risk of HPAI introduction into dairies through wild bird exposure.

Since the first cattle outbreak in Texas we've also seen - in addition to (1) HPAI H5 in goats and (2) alpacas in the United States - (3) serological evidence of HPAI exposure in goats and sheep in Pakistan, (4) the UK's Defra reported H5N1 Detected In Domestic Sheep with Mastitis last spring, and again in May; (5) we saw serological evidence of H5N1 in sheep in Norway.

This growing evidence that it wasn't just the North American genotype B3.13 that posed a threat to (dairy) cattle finally led to the following WOAH Statement last October on High Pathogenicity Avian Influenza (HPAI) in Cattle, calling for increased surveillance and testing. 

Early yesterday evening (Friday) the USDA announced that the aforementioned Wisconsin herd has also tested positive for the D1.1 genotype, calling it yet another spillover event. 

Update: Genetic Sequencing Results for Wisconsin Dairy Herd Detection of Highly Pathogenic Avian Influenza

Contact: aphispress@usda.gov

WASHINGTON, D.C., December 19, 2025—On December 14, 2025, USDA’s Animal and Plant Health Inspection Service (APHIS) announced the first detection of highly pathogenic avian influenza (HPAI) in a dairy herd in Wisconsin. On December 17, the National Veterinary Services Laboratories (NVSL) completed whole genome sequencing and confirmed that the virus is H5N1 clade 2.3.4.4b genotype D1.1. Analysis indicates that this detection is a new spillover event from wildlife into dairy cattle, separate from previous events.

Key Points

• Most detections in U.S. dairy herds have resulted from movements linked to the original spillover event that occurred in the Texas Panhandle in late 2023, involving the B3.13 strain.
• In early 2025, through the National Milk Testing Strategy, USDA detected two spillover events in Nevada and Arizona dairy herds. Both were identified early, and no further herd infections occurred through animal movements. These events involved the D1.1 strain.
• The Wisconsin herd, also detected through the National Milk Testing Strategy, represents a new, separate spillover event and involves the D1.1 strain. At this time, no additional dairy herds have been identified as infected in association with this event.

Public Health and Food Safety

This detection does not pose a risk to consumer health or affect the safety of the commercial milk supply. Pasteurization effectively inactivates HPAI virus, and milk from affected animals is diverted or destroyed to prevent entry into the food supply. The Centers for Disease Control and Prevention (CDC) continues to consider the risk to the public to be low.

The Importance of Biosecurity

USDA remains committed to working with state partners to monitor, investigate, and mitigate the spread of HPAI in livestock. The detection does not change USDA’s HPAI eradication strategy. Biosecurity is still key to mitigating the risk of disease introduction or spread between premises.

APHIS recommends enhanced biosecurity measures for all dairy farms. Producers should immediately report any livestock with clinical signs, or any unusual sick or dead wildlife, to their state veterinarian.

Until early 2024 there was scant evidence that HPAI H5 could naturally infect ruminants, but as we saw 10 weeks ago in Preprint: The Potential of H5N1 Viruses to Adapt to Bovine Cells Varies Throughout Evolution, H5N1s ability to infect bovines (and other mammals) has changed markedly in recent years.  

Phenotypes of the Reassortant viruses observed in this study

Currently the threat of the `bovine' B3.13 genotype to humans is perceived as being less than from other, more virulent, strains. But this expansion of genotypes capable of spilling over to bovines and other mammals could increase that threat.

So much so, that two weeks ago we looked at WPRO Table-Top Exercise Crystal: A `Bovine' Novel Flu Outbreak Scenario, which envisioned `. . . a novel influenza A infection related to dairy farms, with sustained human-to-human transmissions and further spread to many countries.'

This is, as far as I can tell, the first large-scale international acknowledgement that a mammalian livestock driven novel flu epidemic was plausible.

As to how likely it might be, only time will tell. 

Virulence: Cats Are More Susceptible to the Prevalent H3 Subtype Influenza Viruses Than Dogs

 Cats Infected With H7N2 - NYC 2016

#18,993

Nine years ago this week the New York City Health Department Issued a Statement On An Avian H7N2 Outbreak In Cats, that quickly spread across multiple animal shelters in NYC. 

Initially (on Dec 14th, 2016) it was announced that that 45 cats at a  Manhattan shelter were infected with an LPAI H7N2 virus, but that number would increase nearly 10-fold in the days to come. 

A week later, the plot thickened, when the NYC Health Department released a Statement On the Human H7N2 Infection of a veterinarian working at one of the shelters. 

While not at the top of our pandemic concerns, in 2007 four people were presumed to have been infected by H7N2 in the UK following local outbreaks in poultry (see Eurosurveillance report). 

Two years later, in J Infect Dis: Serological Evidence Of H7N2 Infection Among Animal Shelter Workers, NYC 2016, we would see evidence that at least at least one other animal worker showed serological evidence of prior infection, and 5 others exhibited low positive titers to the virus, indicating possible infection.

While the exact source of this outbreak remains unknown, it likely started with a stray cat's chance encounter with an infected bird.

Although we'd seen sporadic reports of cats infected with H5N1 - particularly in Asian zoos which fed raw chicken to captive tigers - this was a wake-up call for the potential for cats (and potentially other companion animals) to serve as intermediary hosts for other types of zoonotic influenza. 

Cats As Potential Vectors/Mixing Vessels for Novel Flu

Since then, we've seen hundreds of cats infected with HPAI H5 (see One Health: Outbreak of HPAI a(H5N1) Among House Cats: A Case Series Involving Oseltamivir Treatment) in both the United States and around the world, along with sporadic reports of other avian flu spillovers, including H3N8 in China. 

A few (of many) past blogs includes:

J. Virulence: HPAI H5N1 Virus Infection In Companion Animals

Viruses: The Seroprevalence of Influenza A Virus Infections in Polish Cats During a Feline H5N1 Influenza Outbreak in 2023

CDC MMWR: HPAI H5N1 Virus Infection of Indoor Domestic Cats Within Dairy Industry Worker Households — Michigan, May 2024

Emerg. Microbes & Inf.: Marked Neurotropism and Potential Adaptation of H5N1 Clade 2.3.4.4.b Virus in Naturally Infected Domestic Cats

As we've previously noted (see below), China has recently become increasingly concerned over the evolution and spread of several novel H3 viruses. 

• Preprint: Fatal Human H3N8 Influenza Virus has a Moderate Pandemic Risk.

• Emerg Microbes Infect: A fatal Case of Acute Encephalitis Associated with a Novel influenza H3N2 Recombinant Virus Possessing Human-origin H7N9 Internal Genes 

• Virology: Assessment of the Public Health Risk of Novel Reassortant H3N3 Avian Influenza Viruses That Emerged in Chickens

• Preprint: Fatal infection of a novel canine/human reassortant H3N2 influenza A virus in the zoo-housed golden monkeys

All of which brings us to new study, published this week in the journal Virulence, which finds that cats are far more susceptible to influenza H3 infection than dogs, making them a plausible intermediate host. 

First, the link and some excerpts from the study (but follow the link to read it in its entirety), after which I'll have a brief postscript. 

 

Cats are more susceptible to the prevalent H3 subtype influenza viruses than dogs

Jie Deng , Chunhui Ma , Junting Yu , Bo Chen , Shoujun Li  & Pei Zhou 

Article: 2605799 | Received 06 May 2025, Accepted 13 Dec 2025, Accepted author version posted online: 17 Dec 2025

Cite this article https://doi.org/10.1080/21505594.2025.2605799  

 

ABSTRACT

Recent reports have highlighted the increasing frequency of influenza A virus (IAV) spillover events from other species to dogs and cats. IAV, particularly the H3 subtype, exhibits a broad host range and a propensity for interspecies transmission, as exemplified by the sustained circulation of H3N2 and H3N8 canine influenza viruses in dog populations. This raises concerns about the potential role of companion animals as intermediate hosts in influenza virus transmission. 

To evaluate the susceptibility of dogs and cats to the prevalent H3 subtype influenza viruses, we experimentally inoculated groups of both species with three prevalent influenza viruses: H3N2 avian influenza virus (AIV), H3N8 avian influenza virus, and H3N2 swine influenza virus (SIV). Results showed that while all inoculated dogs exhibited seroconversion to all three viruses at 7, 14, and 21 days post-inoculation (dpi), they displayed no clinical signs, viral shedding, or evidence of viral replication in their organ tissues. 

In contrast, despite the cats did not exhibit apparent clinical signs, all inoculated cats exhibited seroconversion to all viruses at 7, 14 and 21 dpi, sustained nasal viral shedding for approximately one week, and demonstrated viral replication in their lungs, trachea, and nasal turbinate.

Our findings underscore the higher susceptibility of cats compared to dogs to H3 subtype influenza viruses. These results emphasize the critical need for enhanced surveillance of cats within the influenza virus transmission network.

        (SNIP)

Through experimental infection, our study significantly advances our understanding of the infectivity and pathogenicity of various H3 subtype influenza viruses in dogs and cats. Based on our previous studies and the current findings, we can conclude that dogs are resistant to H3N8 EIV2, H3N2 AIV, H3N8 AIV, and H3N2 SIV, while cats are susceptible to H3N8 EIV2, H3N2 AIV, H3N8 AIV, H3N2 SIV, and H3N2 CIV (Table 1).

This pronounced susceptibility of cats, however, contrasts with the epidemiological observation that stable influenza virus circulation has become established in dog populations (e.g., equine-origin H3N8 CIV and avian-origin H3N2 CIV) but not in cats.

A critical factor explaining this paradox is the demographic behavior of cats. Specifically, efficient cat-to-cat transmission is highly dependent on close contact, a condition typically limited in dispersed household settings but readily met in high-density confined environments such as animal shelters.

This demographic constraint is supported by historical evidence of H7N2 and H3N2 influenza outbreaks in feline shelters (Figure1), underscoring the imperative for targeted surveillance in populations where close proximity may promote viral adaptation and sustained transmission.

       (Continue . . . )

While we are understandably focused on the potential for HPAI H5 to spark a pandemic, history suggests that H1, H2, or H3 (avian/swine/canine) novel flu viruses are far more likely to do so (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?). 

Trying to predict what pathogen will win the genetic lottery and spark the next global public health crisis is a mug's game. There are just too many viral contenders, and far too little surveillance and reporting. 

But another pandemic - whether from influenza A, another coronavirus, or something completely out of left field - is all but inevitable. 

The only real question is, will we be ready?

WHO EURO Statement: More than half of WHO European Region experiencing intense, early influenza season driven by new strain

Credit WHO Global Respiratory Rept #556

#19,992


For the past 6 weeks we've been following reports of unusual seasonal flu activity - both in the Southern and Northern Hemispheres - which has been attributed to the recent emergence of a `drifted' H3N2 virus (subclade K), which dominated the Southern Hemisphere's flu season.

A month ago, in UKHSA Preprint: Early Influenza Virus Characterisation and Vaccine Effectiveness in England in Autumn 2025, A Period Dominated by Influenza A(H3N2) Subclade K, we saw early evidence that the 2025-2026 Northern Hemisphere vaccine may not be as effective against this emerging strain, although it is still expected to provide some protection against severe disease. 

Unusually -  Australia's flu season - which would normally have ended in August - continues (albeit well off the highs of July) well into their summer (see Australian CDC chart below)

Over the past six weeks we've also seen reports of uncharacteristically early, and robust, flu outbreaks in places like Japan, South Korea, China, and much of Europe. Some countries are now urging the public to wear face masks in public, and many school closures have been reported.

According to the most recent CDC FluView (Week 49), influenza is slowly rising in the United States, but it hasn't really taken off yet (see map below).   

While Europe's flu woes aren't guaranteed to be duplicated here, the odds are pretty high that the above picture will change radically in the the weeks ahead.  Which means, if you haven't gotten a flu shot, there is still time. 

More than half of WHO European Region experiencing intense, early influenza season driven by new strain
17 December 2025
Media release

17 December 2025 | Copenhagen

Influenza is sweeping across the European Region earlier than usual, with a newly dominant virus strain placing health systems under significant pressure in some countries. The public is recommended to take simple protective action to keep themselves and others safe this winter.

The influenza season has begun roughly 4 weeks earlier than in previous seasons. At least 27 of the 38 countries reporting data in the WHO European Region are now seeing high or very high influenza activity. In 6 countries – Ireland, Kyrgyzstan, Montenegro, Serbia, Slovenia and the United Kingdom – more than half of patients tested for influenza-like illness were positive for influenza.

“The flu comes around every winter, but this year is a little different,” said Dr Hans Henri P. Kluge, WHO Regional Director for Europe. “A new strain – A(H3N2) subclade K – is driving infections, though there is no evidence that it causes more severe disease. This new variant of seasonal flu now accounts for up to 90% of all confirmed influenza cases in the European Region. It shows how even a small genetic variation in the flu virus can place enormous pressure on our health systems because people do not have built-up immunity against it.”

While it may not prevent infection, early data from the United Kingdom confirm that the current seasonal influenza vaccine lowers the risk of severe health outcomes from A(H3N2) influenza virus. Vaccination remains the single most important preventive step to avoid severe health outcomes. This is especially important for those at higher risk, including older people, those with underlying conditions, pregnant women and children. In addition, health workers are also a priority group for vaccination to protect their own health and the health of their patients.

As in other seasons, school-aged children are the primary drivers of community spread. However, adults aged 65 and older constitute the majority of severe cases requiring hospitalization, highlighting their critical priority for vaccination.

How to stay safe this winter

Cases will continue to rise until the influenza season peaks, likely in late December or early January. Most people will recover from influenza on their own. People with severe symptoms or other medical conditions should seek medical care.

WHO reiterates proven measures to curb transmission and save lives.

• Get vaccinated. This is the best defence, especially for high-risk priority groups and health workers, who should also follow infection prevention measures and wear a mask when necessary.

• Stop the spread. Stay home if unwell. If you have respiratory symptoms, wear a mask in public to prevent passing the virus to others. When sneezing or coughing, cover your mouth and nose. Clean hands regularly. Open windows and doors frequently to improve air flow indoors.

“The current flu season, though serious, does not represent the level of global emergency we faced during the COVID-19 pandemic. Our health systems have decades of experience managing influenza, we have safe vaccines that are updated annually and we have a clear playbook of protective measures that work. If we use the proven tools that we already have – vaccination, health-conscious behaviour and strong public health systems to protect the most vulnerable – then we will weather this predictable, seasonal storm.”

“It is also vital in the current climate of mis- and disinformation to seek credible information from trusted sources like national health agencies and WHO,” concluded Dr Kluge. “In a challenging flu season, trustworthy evidence-based information can be life-saving.”