This is bad news. It suggests reassortment of circulating H5N1 viruses with viruses containing N9 NA.
Although this indicates reassortment with avian viruses, it's still bad. Reassortment makes pandemics. The last 3/4 flu pandemics (and likely 1918 too) were reassortant viruses.
Although this indicates reassortment with avian viruses, it's still bad. Reassortment makes pandemics. The last 3/4 flu pandemics (and likely 1918 too) were reassortant viruses.
1st U.S. case of H5N9 bird flu (different from H5N1) reported on California duck farm
1st U.S. case of H5N9 bird flu reported on California duck farm - National | Globalnews.ca
The United States has reported its first outbreak of H5N9 bird flu in poultry on a duck farm in California, the World Organization for Animal Health (WOAH) said on Monday.
globalnews.ca
January 27, 2025 at 10:43 PM
This is bad news. It suggests reassortment of circulating H5N1 viruses with viruses containing N9 NA.
Although this indicates reassortment with avian viruses, it's still bad. Reassortment makes pandemics. The last 3/4 flu pandemics (and likely 1918 too) were reassortant viruses.
Although this indicates reassortment with avian viruses, it's still bad. Reassortment makes pandemics. The last 3/4 flu pandemics (and likely 1918 too) were reassortant viruses.
Beware. Conditions are prime for a H5N1 reassortment event.
December 19, 2025 at 10:51 PM
Beware. Conditions are prime for a H5N1 reassortment event.
#Influenza viruses have 8 genome segments. When 2 infect the same host, evolution can shuffle the deck. Our new EID Perspective examines reassortment and #H5N1 spillover in Asia and why surveillance must detect what viruses have become.
wwwnc.cdc.gov/eid/article/...
wwwnc.cdc.gov/eid/article/...
Reassortment of Highly Pathogenic Avian Influenza as a Driver for Zoonotic Spillover, Asia
Reassortment of HPAI as Driver for Spillover
wwwnc.cdc.gov
September 21, 2026 at 2:41 AM
#Influenza viruses have 8 genome segments. When 2 infect the same host, evolution can shuffle the deck. Our new EID Perspective examines reassortment and #H5N1 spillover in Asia and why surveillance must detect what viruses have become.
wwwnc.cdc.gov/eid/article/...
wwwnc.cdc.gov/eid/article/...
Preventing reassortment in other susceptible mammalian species should be a high priority for influenza control
Serological evidence for highly pathogenic avian influenza H5N1 in horses. Because H3N8 equine influenza virus is endemic in many countries, horses should be monitored to prevent reassortment between equine and avian influenza viruses with unknown consequences. wwwnc.cdc.gov/eid/article/...
December 9, 2024 at 9:15 AM
Preventing reassortment in other susceptible mammalian species should be a high priority for influenza control
This is awful.
Now imagine a reassortment event in the avian influenza virus triggering human-to-human spread.
Now imagine a reassortment event in the avian influenza virus triggering human-to-human spread.
March 12, 2026 at 6:15 PM
This is awful.
Now imagine a reassortment event in the avian influenza virus triggering human-to-human spread.
Now imagine a reassortment event in the avian influenza virus triggering human-to-human spread.
I'm honestly thinking they are worried about an H5N1 reassortment event
January 11, 2025 at 1:09 AM
I'm honestly thinking they are worried about an H5N1 reassortment event
Note: I see the CIDRAP writer called this "reassortant" several times in the article but I believe that should read "reassortment". Reassortment is when a gene segment is replaced from another virus during a co-infection.
January 27, 2025 at 9:25 PM
Note: I see the CIDRAP writer called this "reassortant" several times in the article but I believe that should read "reassortment". Reassortment is when a gene segment is replaced from another virus during a co-infection.
2. With flu season about to start in the Northern Hemisphere, the risk of reassortment through co-infection will rise dramatically.
/end
/end
October 31, 2025 at 11:03 AM
2. With flu season about to start in the Northern Hemisphere, the risk of reassortment through co-infection will rise dramatically.
/end
/end
Increasing prevalence of H5N1 globally, drastically reduced surveillance in the US, H3N2 driving a severe flu season in the Northern Hemisphere, a mismatched flu vaccine, and the possibility of undetected human - human transmission of H5N1 is a recipe for a reassortment event.
November 14, 2025 at 10:14 AM
Increasing prevalence of H5N1 globally, drastically reduced surveillance in the US, H3N2 driving a severe flu season in the Northern Hemisphere, a mismatched flu vaccine, and the possibility of undetected human - human transmission of H5N1 is a recipe for a reassortment event.
A. Rasmussen: "H5N9 detection suggests reassortment of circulating H5N1 viruses with avian flu virus that contains the N9 neuraminidase (NA). She added that replication in coinfected hosts can produce unpredictable new reassortment viruses"
www.cidrap.umn.edu/avian-influe...
www.cidrap.umn.edu/avian-influe...
Tests identify H5N9 avian flu at California duck farm
www.cidrap.umn.edu
January 27, 2025 at 9:17 PM
A. Rasmussen: "H5N9 detection suggests reassortment of circulating H5N1 viruses with avian flu virus that contains the N9 neuraminidase (NA). She added that replication in coinfected hosts can produce unpredictable new reassortment viruses"
www.cidrap.umn.edu/avian-influe...
www.cidrap.umn.edu/avian-influe...
1. Like everyone else in the biodefense community, I've been watching H5N1 like a hawk since long before SARS-CoV-2 emerged. H5N1 could easily undergo reassortment with another influenza strain to create a reassortant virus with a significant CFR and efficient human transmission.
December 13, 2025 at 12:34 PM
1. Like everyone else in the biodefense community, I've been watching H5N1 like a hawk since long before SARS-CoV-2 emerged. H5N1 could easily undergo reassortment with another influenza strain to create a reassortant virus with a significant CFR and efficient human transmission.
In mammal hosts, we see the opposite: lower reassortment rates, but higher rates of selection. Swine viruses are unique in that they harbor high reassortment and selection, supporting their potential to generate new diversity. In swine, reassortant viruses are also more likely to persist
September 23, 2026 at 9:04 PM
In mammal hosts, we see the opposite: lower reassortment rates, but higher rates of selection. Swine viruses are unique in that they harbor high reassortment and selection, supporting their potential to generate new diversity. In swine, reassortant viruses are also more likely to persist
And human flu season beginning, with so many potential reassortment events. Hopefully we'll get lucky but damn, stakes are high if we're not.
One mutation. One single mutation. In an environment in which H5N1 is infecting multiple species (including humans) and a vast total number of infections.
www.latimes.com/environment/...
www.latimes.com/environment/...
Just one mutation can make H5N1 bird flu a threat to humans, California researchers say
The Scripps Research Institute finding counters prevailing thought that the virus would require multiple mutations before it poses a threat to public health.
www.latimes.com
December 5, 2024 at 8:49 PM
And human flu season beginning, with so many potential reassortment events. Hopefully we'll get lucky but damn, stakes are high if we're not.
“I’m worried about H5N1 in patients who are being treated in hospitals where there are also many patients with seasonal flu because this creates opportunity for reassortment, which could produce a pandemic-capable H5N1”
Can we have mandatory masking in healthcare now? Clean air? Infection control?
Can we have mandatory masking in healthcare now? Clean air? Infection control?
April 4, 2025 at 8:06 PM
“I’m worried about H5N1 in patients who are being treated in hospitals where there are also many patients with seasonal flu because this creates opportunity for reassortment, which could produce a pandemic-capable H5N1”
Can we have mandatory masking in healthcare now? Clean air? Infection control?
Can we have mandatory masking in healthcare now? Clean air? Infection control?
of H3Nx viruses from these species, and then developed a pipeline to quantify reassortment in technical replicate, allowing us to quantify patterns of selection and reassortment with statistical uncertainty. We could then measure how selection and reassortment rates and patterns operate in the
September 23, 2026 at 9:04 PM
of H3Nx viruses from these species, and then developed a pipeline to quantify reassortment in technical replicate, allowing us to quantify patterns of selection and reassortment with statistical uncertainty. We could then measure how selection and reassortment rates and patterns operate in the
Recently, an H5N1-infected pig raised significant concern due to the unique role pigs can play in influenza virus evolution. As hosts capable of being infected by multiple influenza virus subtypes, pigs provide an environment for a viruses' genetic reassortment.
December 25, 2024 at 5:56 PM
Recently, an H5N1-infected pig raised significant concern due to the unique role pigs can play in influenza virus evolution. As hosts capable of being infected by multiple influenza virus subtypes, pigs provide an environment for a viruses' genetic reassortment.
Our lab just put out a new preprint! Led by Maria Maltepes, we've been working with @tavisanderson.bsky.social and @alexey-markin.bsky.social to understand how host species impacts the fundamentals of how influenza viruses evolve. TLDR, reassortment and selection rates vary widely across species.
scholar.google.com
September 23, 2026 at 9:04 PM
Our lab just put out a new preprint! Led by Maria Maltepes, we've been working with @tavisanderson.bsky.social and @alexey-markin.bsky.social to understand how host species impacts the fundamentals of how influenza viruses evolve. TLDR, reassortment and selection rates vary widely across species.
The rare #birdflu strain recently found in Calif ducks—H5N9—is raising the specter of wider spread among birds.It's also under scrutiny for evidence of genetic reassortment—gene swapping—w/ other flu strains, even #H5N1. That might lead to a new virus that spreads easily among humans wapo.st/3PYBG16
Rare bird flu strain found in California raises potential of wider spread
First U.S. detection of virulent H5N9 strain, at a California duck farm, draws scrutiny as evidence of genetic reassortment that could trigger human outbreaks.
wapo.st
January 31, 2025 at 12:10 PM
The rare #birdflu strain recently found in Calif ducks—H5N9—is raising the specter of wider spread among birds.It's also under scrutiny for evidence of genetic reassortment—gene swapping—w/ other flu strains, even #H5N1. That might lead to a new virus that spreads easily among humans wapo.st/3PYBG16
They should have been.
- Testing dairy and poultry workers
- Providing PPE for these workers
- Providing currently available H5N1 vaccines to these workers
- Doing regular testing of cattle and milk
- Strongly promoting seasonal flu vaccines to the public to prevent reassortment to lethal strains
- Testing dairy and poultry workers
- Providing PPE for these workers
- Providing currently available H5N1 vaccines to these workers
- Doing regular testing of cattle and milk
- Strongly promoting seasonal flu vaccines to the public to prevent reassortment to lethal strains
May 22, 2025 at 5:09 PM
They should have been.
- Testing dairy and poultry workers
- Providing PPE for these workers
- Providing currently available H5N1 vaccines to these workers
- Doing regular testing of cattle and milk
- Strongly promoting seasonal flu vaccines to the public to prevent reassortment to lethal strains
- Testing dairy and poultry workers
- Providing PPE for these workers
- Providing currently available H5N1 vaccines to these workers
- Doing regular testing of cattle and milk
- Strongly promoting seasonal flu vaccines to the public to prevent reassortment to lethal strains
This is called reassortment.
From the CDC:
"Reassortment can result in the emergence of new influenza A viruses with new or different properties, such as the ability to spread more easily among animals or people."
From the CDC:
"Reassortment can result in the emergence of new influenza A viruses with new or different properties, such as the ability to spread more easily among animals or people."
December 19, 2024 at 8:37 PM
This is called reassortment.
From the CDC:
"Reassortment can result in the emergence of new influenza A viruses with new or different properties, such as the ability to spread more easily among animals or people."
From the CDC:
"Reassortment can result in the emergence of new influenza A viruses with new or different properties, such as the ability to spread more easily among animals or people."
Check out this amazing work on reassortment of H3Nx viruses from the Moncla lab!
Our lab just put out a new preprint! Led by Maria Maltepes, we've been working with @tavisanderson.bsky.social and @alexey-markin.bsky.social to understand how host species impacts the fundamentals of how influenza viruses evolve. TLDR, reassortment and selection rates vary widely across species.
scholar.google.com
September 24, 2026 at 4:01 AM
Check out this amazing work on reassortment of H3Nx viruses from the Moncla lab!
The sheer amount of H5N1 circulating in North America is deeply concerning. My suspicion is that the likelihood of a reassortment event with seasonal flu occurring is now high. Make no mistake, this situation has pandemic potential.
Stunning: 58 new #H5N1 #birdflu infected herds in California confirmed by #USDA today.
The US dairy industry needs to have a long think about biosecurity. If H5 killed cows, the industry would be sunk. www.aphis.usda.gov/livestock-po...
The US dairy industry needs to have a long think about biosecurity. If H5 killed cows, the industry would be sunk. www.aphis.usda.gov/livestock-po...
December 12, 2024 at 3:47 PM
The sheer amount of H5N1 circulating in North America is deeply concerning. My suspicion is that the likelihood of a reassortment event with seasonal flu occurring is now high. Make no mistake, this situation has pandemic potential.
than non-reassortants, suggesting a potential fitness advantage. We also find host-specific differences in segment reassortment patterns, although we don't know why that is.
Overall, these data suggest that the roles of mutation and reassortment in driving H3Nx evolution is fundamentally shaped
Overall, these data suggest that the roles of mutation and reassortment in driving H3Nx evolution is fundamentally shaped
September 23, 2026 at 9:04 PM
than non-reassortants, suggesting a potential fitness advantage. We also find host-specific differences in segment reassortment patterns, although we don't know why that is.
Overall, these data suggest that the roles of mutation and reassortment in driving H3Nx evolution is fundamentally shaped
Overall, these data suggest that the roles of mutation and reassortment in driving H3Nx evolution is fundamentally shaped
Increasing concerns regarding viral reassortment and missed cases during the 2024/2025 seasonal flu season should prompt a rapid distribution of this available vaccine now.
December 25, 2024 at 5:56 PM
Increasing concerns regarding viral reassortment and missed cases during the 2024/2025 seasonal flu season should prompt a rapid distribution of this available vaccine now.
what would you expect about the heritability of intelligence, presuming a normal level of reassortment, if the relationship between genetics and IQ was (a) highly polygenic and (b) nonconvex, as Hsu claims.
May 28, 2025 at 5:13 PM
what would you expect about the heritability of intelligence, presuming a normal level of reassortment, if the relationship between genetics and IQ was (a) highly polygenic and (b) nonconvex, as Hsu claims.