Monday, March 23, 2026

(Referral) Nature: Human MERS-CoV cases are falling but pose an ongoing pandemic threat

 

#19,093

Since the arrival of the COVID pandemic we've witnesses a sharp, and welcome, decline in the number of MERS-CoV cases reported from the Middle East. 

At first, it was thought this respite was due the the `fog' of the pandemic, and shifting surveillance priorities. 

While detection and reporting of cases has always been challenging (see EID Journal: Estimation of Severe MERS Cases in the Middle East, 2012–2016), this decline now seems legit; potentially caused by a combination of:

  • Possible limited cross-protection due to COVID (infection and/or vaccination).
  • Behavior changes (mask wearing, better hand hygiene, reduced camel contact, etc.) since COVID
  • Improved infection control (again, likely driven by COVID) in healthcare facilities, which often accounted for large outbreaks previously.
Encouraging, but none of these changes are guaranteed to be permanent. Over time acquired immunity can wane, behaviors can change, and lapses in infection control can always resume. 

While the number of cases remains low, over the past 12 months we've seen several high-profile reports of spillovers, including France MOH: 2 Travelers Returning From Arabian Peninsula Diagnosed with MERS-CoV  and WHO: Saudi Arabia Reports 9 New MERS-CoV Cases.

Not surprisingly, over the past year we've also seen a resurgence in MERS-CoV-related studies, including:


All of which brings us to a WHO-authored commentary - published last week in Nature - which warns that the MERS-CoV continues to circulate in dromedary camels in the Middle East, that it appears to maintain its virulence, and it remains a plausible pandemic threat.

Since this is not an Open Access report released under the CC license, I've only posted the link below.  It is free to read, but you may have to set up an account. 

Nevertheless, it is well worth reading in its entirety.  I'll have a bit more after you return.

Comment
Published: 19 March 2026

Human MERS-CoV cases are falling but pose an ongoing pandemic threat

Lorenzo Subissi, James R. Otieno, Asma Abi Mohamed Shah, Laith Jamal Abu-Raddad, Anurag Agrawal, Amna Omair Al Mehairi, Ahmed Mohammed Albarraq,  Amal Barakat, Ismail Mahat Bashir, Leon Caly, Meera Chand, Christian Drosten, Nuno R. Faria, Adeola Fowotade, Anne von Gottberg, Bart L. Haagmans, Baoying Huang, Jason Kindrachuk, Marion P. G. Koopmans, Bette Korber, Yee-Sin Leo,  Placide Mbala-Kingebeni, Nada M. Melhem, Vincent J. Munster, …Maria D. Van Kerkhove 

Nature Health (2026) Cite this article

Human cases of Middle East respiratory syndrome coronavirus (MERS-CoV) have declined in recent years, but continued surveillance and research is needed to understand this trend and mitigate future zoonotic threats.

While MERS-CoV and new variants of SARS-CoV-2 are both plausible candidates for producing the next pandemic, we continue to watch a growing number of novel coronavirus threats in the wild.

Just a few, of many, include:






Recent studies suggest that the frequency, and impact, of pandemics are only expected to increase in the years ahead.


While I can't tell you what type of emerging disease will spark the next pandemic - or when - it is all but guaranteed to happen again. And very much like we were in the run-up to COVID, the world is nowhere near prepared to go through that again.

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Sunday, March 22, 2026

Vet Research Comms: First report of serological and molecular detection of influenza A (H1N1) in European bison (Bison bonasus)

 

European Bison - Credit Wikipedia

#19,092


It was 2 years ago this week (March 24th, 2024) that I wrote about Curious Reports of Unknown Disease In Dairy Cows (Texas, Kansas & New Mexico), that in short order would be identified as HPAI H5N1.

HPAI testing appears to have been delayed for several weeks because - up until then - cattle had been considered poorly susceptible to influenza A (see A Brief History Of Influenza A In Cattle/Ruminants), despite successful experimental infection with H5N1.  

Since then we've seen more than 1,000 dairy herds infected with HPAI H5 in the United States, along with spillovers to goats, pigs, and alpacas. Testing remains largely voluntary, however,  and some estimates suggest that significant under-reporting of H5N1 in dairy herds is likely.

Over the past two years we've seen a number of studies suggesting that Influenza A in general (including HPAI H5), can and does infect livestock, including bovines, pigs, and goats.  A few of many studies include:
Netherlands: NOS.NL Reports 5 Dairy Cows Have Now Tested Positive for H5N1

Preprint: Highly Pathogenic Avian Influenza H5 Virus Exposure in Goats and Sheep (in Pakistan).

Germany FLI: Statement On Experimental Infection Of Dairy Cows With European H5N1 Virus 

Despite this growing resume, much of the world continues to act as if the spillover of HPAI H5 is somehow just an `American problem' - due to an aberrant local strain of the virus - and unlikely to spread beyond our borders.

Last October, WOAH embraced an 11-page OFFLU technical document (see OFFLU Guidelines for High Pathogenicity Avian Influenza Virus Risk Mitigation in Cattle) which - among other things - finally made HPAI in cattle a `reportable disease'. 

But it isn't at all clear how seriously governments and farmers are taking these recommendations - both here in the United States - and around the world.  

Today we've another (admittedly minor) data point; The first detection of influenza A (H1N1pdm) in a European Bison. This comes from a retrospective study, using samples collected between 2017 and 2023, and the positive sample came from 2018.

Almost all of the testing of cattle for HPAI in the United States (and elsewhere) has been conducted on lactating cows, but this detection was in a 4 year-old male bison which lived at a farm in Poland.

This report is notable because it adds yet another wild ruminant species to the list of  influenza A susceptible mammals, and it highlights the risks of bidirectional spillover of IAV at the wildlife-livestock-human interface.

I've just reproduced the abstract. Follow the link to read the report in its entirety. I'll have a brief postscript after the break.

First report of serological and molecular detection of influenza A (H1N1) in European bison (Bison bonasus)

Brief Report
Open access
Published: 21 March 2026
Volume 50, article number 212, (2026)
Veterinary Research Communications

Download PDF

Anna Didkowska, Víctor Martín-Santander, Anna Golke, Marlena Wojciechowska, Wanda Olech, Olga Szaluś-Jordanow, Tomasz Dzieciątkowski, Álex Gómez, Sergio Villanueva-Saz, Ewelina Kwiecień, Pablo Quilez, Krzysztof Anusz & Diana Marteles-Aragüés 

Abstract

Influenza A virus is a zoonotic pathogen capable of infecting a wide range of hosts, yet data on infections in wild ruminants are limited. The European bison (Bison bonasus), Europe’s largest terrestrial mammal, had not previously been identified as a host for Influenza A virus. This study aimed to provide the first molecular and serological evidence of H1N1 pandemic influenza A virus (A/H1N1pdm) infection in European bison, contributing to the understanding of Influenza A virus ecology at the wildlife–livestock interface. 

We retrospectively analysed 335 serum samples collected from European bison between 2017 and 2023 using a commercial ELISA detecting antibodies against all Influenza A virus subtypes. Tissue samples (heart and liver) from ELISA-positive animal were further tested by RT-qPCR targeting hemagglutinin (HA) and neuraminidase (NA) genes of A/H1N1pdm, A/H3N2, and A/H5N1. PCR-positive products were sequenced for confirmation.

Seroprevalence of Influenza A virus was 0.3% (1/335; 95% CI: 0.02–1.71). Influenza A virus RNA (A/H1N1pdm) was detected in the heart and liver tissue of a 4-year-old captive male from Borecka Forest, culled in 2018. The animal exhibited pulmonary congestion, emphysema, and posthitis at necropsy. 

This study provides the first molecular and serological confirmation of H1N1pdm infection in European bison. The findings highlight the potential susceptibility of this species to Influenza A virus and raise questions about possible transmission routes, including spillover from domestic animals or humans.

(Continue . . . )

We saw similar detections of (of non-HPAI) influenza A reported in steers and bulls last year in Virology: Detection of Antibodies Against Influenza A Viruses in Cattle, where the authors wrote:

Our results demonstrate that IAVs other than H5N1 can infect cattle, infections are not limited to dairy cows, and that bovine infections with swine and human IAVs have occurred prior to the H5N1 outbreaks.
All results highlight the value in monitoring IAV epidemiology in cattle, as the viruses might adapt to cattle and/or reassort with the currently circulating H5N1 HPAIV, increasing risk to humans.

Yesterday, in Referral: (OFFLU Report) Beyond poultry: Rethinking monitoring and control of HPAI H5Nx anticipating spillover risks for mammals, we saw renewed calls for enhanced surveillance of farmed animals: particularly cattle, goats, sheep, fur bearing mammals, and pigs. 

Last December more than 30 countries participated in a WPRO Table-Top Exercise Crystal: A `Bovine' Novel Flu Outbreak Scenario;' one which envisioned an epidemic that would have been considered by many as bordering on the absurd just 24 months ago.

 

Today, due to the speed at which HPAI is evolving, it is all too plausible.

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Saturday, March 21, 2026

Referral: (OFFLU Report) Beyond poultry: Rethinking monitoring and control of HPAI H5Nx anticipating spillover risks for mammals.

 

WOAH SitRep #79


#19,091

Yesterday OFFLU - the WOAH/FAO joint network of expertise on avian influenza - published a paper from some of the most recognizable names in influenza research, that offers practical steps for combating the growing threat from HPAI H5Nx.

In a nutshell, the authors posit that we can no longer afford to think of HPAI H5Nx as simply an avian or poultry-centric disease. Its epidemiology has changed in recent years to permit sustained, year-round carriage in aquatic birds, and increased spillover to multiple mammals species. 

They argue that surveillance and reporting systems must be adapted to protect animal and human health. They warn that `. . . dedicated HPAI surveillance strategies targeting wild and domestic mammals are largely absent in most countries.' 

They also find the most critical surveillance gap is among farmed mammals, a topic we've covered often (see OFFLU Guidelines for High Pathogenicity Avian Influenza Virus Risk Mitigation in Cattle).

The authors then present a framework for creating a `spillover prevention plan' utilizing a One Health approach. One that focuses prevention and surveillance on four groups of mammals:
  • Mammals housed in groups (livestock, fur farms, zoos, catteries)
  • Companion animals (cats, dogs, etc.)
  • Free‑ranging mammals (wild and feral)
  • Humans with relevant exposures.
As I can find no explicit copyright notice anywhere in the PDF, I'm reluctant to quote extensively from the paper. However, since it is relatively short (7-pages), I can highly recommend following the link to read it its entirety.  

Beyond poultry: Rethinking monitoring and control of HPAI H5Nx anticipating spillover risks formammals.March 2026 

This document was developed by OFFLU, the Network of Expertise on Animal Influenza established by the World Organisation for Animal Health (WOAH) and the Food and Agriculture Organization of the United Nations (FAO), through its Wildlife and Avian Technical Activities. 

Authors and Affiliations Lineke Begeman* 1,2, Fabien Filaire* 1,2, Lorcan Carnegie1 , Martin Beer3 , Francesco Bonfante4 , Nicola Lewis5,6, Guillaume Fournie6,7,8 , Erik A Karlsson9 (OFFLU Vice-Chair), Marcela Uhart10 (OFFLU Chair), Ron Fouchier2 , Thijs Kuiken2 (*contributed equally). 

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Friday, March 20, 2026

UC Davis: High pathogenicity Avian Influenza in Pinniped conservation

 
Credit https://doi.org/10.1098/rstb.2024.0320


#19,090

Just over 3 weeks ago, in California: Background on the Outbreak of H5N1 in Elephant Seals at Año Nuevo Natural Reserve, we looked at early reports from California Parks and UC Santa Cru on the first detection of HPAI H5N1 in North American Elephant Seals.
Initial reports suggested that at least 7 seal pups had tested positive after dozens of seals at California's Año Nuevo Reserve had developed respiratory and neurological symptoms. 

Since then, according to local news outlets (see CIDRAP report), the number of  HPAI positive seals has increased to 16, along with an otter and a sea lion.  The actual count is likely much higher, as only a limited number of mammals have been tested. 

Compared to what we've seen in South America, this remains a small outbreak, but over the past 5 years we've seen evidence of this virus becoming more `mammalian friendly'.  

Dairy cows, domestic cats, and peridomestic animals like mice, skunk, and foxes have all been affected, but marine mammals appears to be close to achieving  sustained mammal-to-mammal transmission. 

    • Several mutations were detected months later in sea lions in the Atlantic coast, indicating that the pinniped outbreaks on the west and east coasts of South America are genetically linked. These data support sustained mammal-to-mammal transmission of HPAIV in marine mammals over thousands of kilometers of Chile’s Pacific coastline, which subsequently continued through the Atlantic coastline.
Although exact numbers are impossible to come by, a little over a year ago in Nature Reviews: The Threat of Avian Influenza H5N1 Looms Over Global Biodiversity, we saw a partial tally.
The most noteworthy mass-mortality events include more than 200,000 wild birds in coastal areas of Peru6; 24,000 sea lions in South America7; 20,500 wild birds in Scotland8; 6,500 Cape cormorants in Namibia9; and 17,400 elephant seals, including >95% of the pups in Argentina10.
These figures, however, largely underestimate actual mortalities, owing to a pervasive lack of monitoring, testing and reporting — particularly in inaccessible areas and in disadvantaged countries4,7.

Aside from the devastating impact on these mammals and the marine ecology, the possibility exists that HPAI could make strides towards human adaptation as it spreads through other mammalian species. 

All of which brings us to a study published earlier this month in Philosophical Transactions B which details the impact of HPAI on pinnipeds, and offers some recommendations on how its impact might be managed. 

Since this article was submitted months before the current outbreak in California, I've included some excerpts from a UC Davis press release which incorporates these latest developments.

The full 17-page PDF can be downloaded at the link below. 

High pathogenicity avian influenza in pinniped conservation 

Elizabeth Ashley; Ralph Eric Thijl Vanstreels; Michelle Barbieri; Wendy Puryear; Frances Gulland; Cara Field; Christine Kreuder Johnson; Marcela Uhart  Published online: 05 Mar 2026 https://doi.org/10.1098/rstb.2024.0320

Abstract

Since 2020, H5Nx high pathogenicity avian influenza viruses (HPAIVs) have caused widespread disruptions not only to global agriculture and trade but also to the health of free-ranging wildlife. Pinnipeds have experienced greater mortality from H5Nx HPAIV than any other mammalian taxa. Emergent virus strains, persisting over long time periods and vast geographic distances, have repeatedly triggered large-scale mortality events in pinniped populations.
Of particular concern is the spread of H5Nx HPAIV to the Southern Hemisphere—including the emergence of a marine mammal-adapted clade in South America and detections in the sub-Antarctic and Antarctic—and to other remote locations such as the Hawaiian Islands. These developments elevate concern for the world’s endangered, isolated and endemic pinnipeds.
While managing HPAIV in any animal population is a formidable task, working with free-ranging marine mammals poses unique challenges. In this review and perspective piece, we attempt to synthesize complexities at this intersection. We describe lessons learned from HPAIV investigations in marine wildlife, highlight gaps in knowledge and capacity, and discuss the incorporation of outbreak risk assessment and countermeasures into pinniped conservation. Finally, we propose ways in which pinnipeds—and marine wildlife broadly—could be better integrated into existing systems for HPAIV intelligence, control and prevention. 

        (Continue . . . )

  
From the press release:

Global strategies to protect seals and sea lions from avian influenza

A birds-eye view of the impacts of H5N1 on pinniped conservation 
University of California - Davis 
News Release 19-Mar-2026
(EXCERPT)

A study from the University of California, Davis, steps back to look at the overall impact of the virus on pinnipeds worldwide and offers recommendations for moving forward to monitor, characterize risk and build resilience in the affected species. It also suggests ways to help prevent the virus from reaching currently unaffected but vulnerable pinniped species, such as the endangered Hawaiian monk seal or Galapagos sea lion.

(SNIP)

“There is a huge, unprecedented conservation risk,” said corresponding author Christine Johnson, director of the Institute for Pandemic Insights at the UC Davis Weill School of Veterinary Medicine. “Influenza is constantly changing, and that is a big problem now that it’s widely circulating in birds and marine mammals.”

(SNIP)

In late February, northern elephant seals in California marked the first cases of HPAI H5N1 in a marine mammal in the state. The speedy detection was due to routine surveillance for H5N1 that was set up over a year prior by UC Davis and Año Nuevo Natural Reserve in collaboration with UC Santa Cruz’s long-term monitoring of the northern elephant seal colony at Año Nuevo State Park.

At the end of 2025, in response to a growing number of H5N1 cases in Bay Area seabirds, the team increased surveying efforts, walking the length of the reserve to document and sample any sick or dead bird or mammal throughout the elephant seal breeding season.

These efforts in advance of the outbreak allowed teams to quickly respond to changes in the seals’ health and collect samples for testing at UC Davis. Johnson called it an “exceptionally rapid detection of an outbreak in free-ranging marine mammals,” and an example of the kinds of preemptive efforts to detect and respond to outbreaks effectively.

The paper’s key recommendations include:

  • Fund and support long-term wildlife monitoring, and conduct surveillance both between and during outbreaks to detect trends early and respond swiftly before outbreaks spread.
  • Build stronger communication and coordination networks among local, national and global researchers, agencies and academic partnerships to prepare for outbreaks. This includes working with public health practitioners and social scientists to engage and protect people at risk of disease exposure.
  • Make wildlife health surveillance a routine part of conservation research and management activities.
  • Improve technologies for non-invasive monitoring. For example, the UC Davis Institute for Pandemic Insights brings together engineers and wildlife health experts to deploy auditory and thermal imagery with satellite imagery to better understand key events or tipping points that may indicate an outbreak is likely.
  • Pursue high-level policy changes and international agreements that address the root causes of avian influenza outbreaks.
  • Address concurrent conservation threats. The authors emphasize that avian influenza is just one of many stressors affecting marine wildlife. Many species face challenges including habitat loss, declining food supply and climate change. Small populations are especially vulnerable.

“H5 avian influenza viruses are an emergent threat to seal and sea lion populations already facing numerous conservation pressures,” said first author Elizabeth Ashley, a graduate student researcher pursuing a dual degree in veterinary medicine and epidemiology at UC Davis. “Understanding how this virus spreads in coastal ecosystems is critical for protecting vulnerable marine wildlife.”

(Continue . . . )

Six months ago, in ISIRV: Update on H5N1 Panzootic: Infected Mammal Species Increase by Almost 50% in Just Over a Year, we looked at the recent inroads this HPAI virus has made into mammalian species (as of July 2025).  
Even if HPAI H5Nx somehow proves incapable of sparking a human pandemic, its impact on our fragile and interconnected biosphere could be devastating.
While I can't tell you exactly what negative impacts the loss of a Billion+ wild birds, a quarter of a million marine mammals - or unfathomable numbers of peridomestic mammals - might have on our society, one thing is certain.

We are well on our way to finding out. 
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Thursday, March 19, 2026

EFSA: Risk communication on Avian Flu Biosecurity

  
Credit EFSA

#19,089

Last August, in H5Nx: Reassort & Repeat, we looked at worrying signs - in both Europe and North America - that this fall's avian flu season might be unusually robust.
Again, in November (see A Robust Start To Avian Flu Season In Europe & North America), we saw additional indications that the recent trend in declining European HPAI outbreaks might be over, and that we could be on the verge of seeing a significant uptick in bird flu activity.

The above graphic from last week's EFSA quarterly report on avian flu confirms those fears, as the number of detections in wild and migratory birds dwarfs anything we've seen before, and the number of affected poultry farms is the highest we've seen in 4 years. 

Europe's avian flu season is far from over, and whatever respite they get over the summer could be short-lived. 

While it is possible that avian flu activity could decline next year, the reality is the virus is now solidly endemic in wild and migratory birds, and the threat is unlikely to go away anytime soon. 

Because of this open-ended threat, the European Commission has asked the EFSA (European Food Safety Authority) to produce a risk communications strategy.

The European Union consists of 27 member countries with 24 `official languages', which can make risk communications difficult. And, as we've seen previously with ECDC guidance, the recommendations in today's technical document are not legally binding. 

This 40-page document is part of a triad of related documents published on March 10th.

Avian flu awareness‐raising campaign communication strategy
Daniela Ulicna, Raphaël De Landsheer, Samuël Costa, Francesca Fumagalli, VERIAN GROUP BELGIUM S.A.
 
Risk communication on biosecurity in relation to poultry ‐ final report
Jenny Castillo, Francesca Porta, Victoria Levery, Noah Tozer, Vincent Fierens

A key point in this risk communications is that while general avian influenza awareness is high - knowledge of symptoms, transmission and specific biosecurity measures is uneven - particularly among small‑scale and backyard keepers who may rely on informal or unreliable channels for information.
 
This report `.  .  . proposes a phased, three-year communication strategy progressing from legitimacy-building to facilitated adoption and long-term reinforcement, supported by a coherent channel architecture and a robust evaluation framework.'

The authors of this report state:

The analysis indicates that a shift is needed from one-off awareness campaigns to structured communication approaches that support farmers across their behavioural journey. This includes improving understanding of why measures matter, building motivation through credible and context‑sensitive messages, and supporting the development of practical skills needed to sustain behaviours over time.

How much of this report is actionable, or will be accepted and pursued by member nations, remains to be seen.  A `phased, three-year plan' also assumes the panoply of HPAI viruses cooperates, and doesn't do anything crazy.

But apparently, what they've been doing up till now hasn't been working. 

I've reproduced the abstract below. Follow the link to read the full report.  I'll have a postscript after the break.

Risk communication on avian flu biosecurity: social research, audience segmentation, and communication strategy for an EU awareness-raising campaign

European Food Safety Authority (EFSA), Anthony I. M. Smith, Angela Bearth, Mario Mazzocchi, Tom Jansen, Wim Verbeke … See all authors
First published: 10 March 2026
https://doi.org/10.2903/sp.efsa.2026.EN-10003Digital Object Identifier (DOI)
 
Requestor: European Commission
Question number: EFSA-Q-2026-00130
Correspondence: Ask a Question

This publication is linked to the following EFSA Supporting Publications articles: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2026.EN-9907; http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2026.EN-10005

PDF
 
Abstract

This report comprises EFSA's response to the European Commission's request for technical assistance in risk communication for a strengthened, evidence-based approach to awareness-raising on avian influenza (AI) biosecurity within the European Union (EU).

It integrates social research, audience segmentation and strategic communication design to inform a multi-year campaign aimed at improving the awareness and consistent uptake of biosecurity measures across diverse poultry-sector stakeholders. Its evidence base derives from two outsourcing activities: social science research and an audience segmentation carried out by ICF, and a multi-year communication strategy undertaken by Verian Group Belgium S.A.. 

These draw on a systematic literature review, 39 in-depth interviews conducted in three EU Member States, Eurostat data, and behavioural analysis using the ADKAR® framework. 

Findings indicate that while general awareness of AI is high, knowledge of transmission pathways, symptoms and the effectiveness of specific biosecurity measures is uneven, particularly among small-scale farmers and backyard keepers. Behavioural, psychological and structural barriers—rather than lack of awareness—limit consistent implementation across segments. 

Five distinct audience segments—four farmer segments and one operational workforce segment—were identified. A sixth group composed of trusted intermediaries, especially veterinarians, emerge as pivotal for communication credibility and behavioural influence. The report proposes a phased, three-year communication strategy progressing from legitimacy-building to facilitated adoption and long-term reinforcement, supported by a coherent channel architecture and a robust evaluation framework.

Overall, the report provides an integrated, evidence-driven foundation for an EU-level biosecurity communication campaign capable of enhancing awareness and resilience, strengthening behavioural uptake and contributing to reduced AI transmission risk across the poultry sector.




 




















Europe is not alone in trying to bridge this `avian flu knowledge gap'; last October we looked at our own  UF/IFAS Extension: What Backyard Flock Owners Need to Know about Bird Flu (Influenza H5N1).  

Even in countries with far more experience dealing with avian flu, compliance with biosecurity has been a constant struggle (see Taiwan: H5N1 Infected Chicken Dumping Incident Investigated).

South Korea has repeatedly stated that this year's wave of HPAI is far more virulent than previous years, and they are operating under an extended state of emergency (South Korea: MAFRA Investigation Into Biosecurity Lapses on HPAI Affected Poultry Farms).

What this means for the future of HPAI is uncertain. Avian flu is constantly mutating, and sometimes that attenuates the threat, and sometimes it increases its impact.

While many governments are loath to speak frankly about the risks of avian flu - we either find better ways to convincingly communicate the risks of HPAI - or risk the virus will find a way to do it for us. 

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Wednesday, March 18, 2026

PLoS Path.: Will Animal Reservoirs Give Us The Next SARS-CoV-2 variant?

 

#19,088

As we discussed on Monday in Nature Comms Med.: Interactions of SARS-CoV-2, Influenza and RSV Influence Epidemic Timing and Risk, a strong flu season can briefly inhibit SARS-CoV-2 transmission at the population level, but that impact is short-lived. 

Which suggests our recent lull in COVID cases is probably temporary, and another spring or summer COVID surge likely awaits. 

Surveillance and reporting on SARS-CoV-2 has deteriorated badly around the world (90% of countries no longer report COVID hospitalizations or deaths), and the WHO published their last comprehensive COVID-19 epidemiological update more than a year ago.

While much remains hidden from view, the SARS-CoV-2 virus continues to circulate, and evolve, around the globe.  And not just in humans. 

Over the years we've looked at the spillover - and onward transmission - of the SARS-CoV-2 virus in a growing number of non-human hosts; including:

PrePrint: Anthropozoonotic Spillovers Reveal Sustained Long-Term Cryptic Circulation of SARS-CoV-2 Within and Between Lithuanian Mink Farms

SARS-CoV-2 Exposure in Norway Rats in New York City

PNAS: White-Tailed Deer as a Wildlife Reservoir for Nearly Extinct SARS-CoV-2 Variants
While some of these were likely limited `dead-end' spillovers, in some species we've seen evidence of vigorous onward transmission, and continued evolution of the virus.  And from at least two of these - white-tailed deer and mink - we've seen evidence of a spillback into humans. 

While none of these spill backs has taken hold in humans (unless you accept the theory that the Omicron variant had a mouse origin), they serve as a proof-of-concept. Unfortunately, our surveillance of non-human hosts for the SARS virus is extremely limited. 

Which brings us to a brief, and refreshingly plain-language `Pearls' article in PLoS Pathogens, which provides a 9-point review of what we know about the threat from cryptic lineages of SARS-CoV-2 spreading in non-human reservoir hosts. 

I've provided the link and a brief excerpt, but this is one you'll definitely want to read in its entirety.  I'll have a bit more after the break.

Davey Smith
Published: March 3, 2026
https://doi.org/10.1371/journal.ppat.1014008


1. What does it mean that SARS-CoV-2 is now a virus with multiple natural hosts?

Like all known human coronaviruses, SARS-CoV-2 originated from animals, most likely through wildlife sold at the Huanan Seafood Market, with bats serving as the deeper evolutionary reservoir [1]. Since its emergence in humans, SARS-CoV-2 has repeatedly crossed into non-human hosts. Over five years of widespread circulation, the virus has been detected in a surprising array of animals, including white-tailed deer, mink, rats, hamsters, horses, cats, zoo animals and dogs, though sustained transmission is clearly documented only in deer and farmed mink, with other species showing limited or no onward spread. For white-tailed deer and mink, the virus has achieved sustained animal-to-animal transmission and spillback to humans [2–6].

This shift transforms SARS-CoV-2 from a purely human epidemic into a network of linked epidemics across species. Humans remain their largest host, but no longer its only long-term home. When a virus gains multiple such homes, it also gains more ecological space and evolutionary possibilities. This article does not address the original zoonotic emergence of coronaviruses broadly; instead, it focuses on the less explored problem: how sustained circulation of SARS-CoV-2 in animal reservoirs may shape future human disease.

       (SNIP)

9. Why should pathogen researchers care, even if they do not work on coronaviruses?

Animal reservoirs slow down viral extinction. They expand the virus’s evolutionary playground. They give SARS-CoV-2 places to mutate where human immunity has little influence. For virologists and pathogenesis researchers of any specialty, these reservoirs show how quickly an emerging virus can become an ecological resident [3]. Ignoring the animal side of SARS-CoV-2 means accepting surprise when spillback occurs. Paying attention gives us a chance to see the next jump coming, and maybe even prevent it.

        (Continue . . . )

Several studies (see BMJ Global: Historical Trends Demonstrate a Pattern of Increasingly Frequent & Severe Zoonotic Spillover Events and PNAS Research: Intensity and Frequency of Extreme Novel Epidemics), suggest the number, frequency, and intensity of pandemics is only expected to increase in the years ahead.

But even if SARS-CoV-2 is unable to fully reinvent itself in a human or non-human host, there are plenty of other coronaviruses circulating in the wild with pandemic potential. 

A few (of many) recent blogs include:

And of course, MERS-CoV continues to circulate and evolve in Arabian (and likely African) camels (see Health Sci Rpts (Narrative Review): Pathogenicity and Potential Role of MERS-CoV in the Emergence of “Disease X”), while occasionally spilling over into humans.

All of which makes it highly unlikely we've seen our last coronavirus threat.
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