Is H5N1 definitely airborne? Convincing proof would have to have unbelievable controls!

"veterinarians were conducting research on a highly secure chicken research farm—the birds there were not allowed out of their cages or barns. The water came from a secure well and was filtered to remove pathogens. The barns have large fans that create a one-way airflow, and the entire facility is surrounded by a highly secure fence.

Also, no employees came into contact with any other birds when not on duty. Still, the farm experienced an infection. The veterinarians suggest the only possibility left is that the virus was carried aloft by the wind and wafted into the barn, settling on the captive birds."

[1]Yup that would do it!

[1] https://phys.org/news/2025-02-evidence-windborne-h5n1-viral-infections.html

2/🧵 about https://www.biorxiv.org/content/10.1101/2025.02.12.637829v1.full.pdf

h/t @JoePajak

#H5N1 #birdFlu #influenza #fluIsAirborne #influenzaIsAirborne #respiratoryDiseasesAreAirborne

To reiterate: ⚠️ "The veterinarians suggest the only possibility left is that the VIRUS WAS CARRIED ALOFT BY THE WIND and wafted into the barn, settling on the captive birds" and infecting them! ⚠️

3/🧵about https://www.biorxiv.org/content/10.1101/2025.02.12.637829v1.full.pdf

#H5N1 #birdFlu #influenza #fluIsAirborne #influenzaIsAirborne #respiratoryDiseasesAreAirborne

h/t @JoePajak

They show "empirical genetic evidence supporting the windborne transmission of the H5N1 HPAI virus over a distance of 8 km, [...] combined with a detailed epizootiological investigation and strong correlation with weather conditions, confirms that wind can transport infectious virus particles over substantial distances and, thereby, facilitate the spread of HPAI between poultry farms."

4/🧵about https://www.biorxiv.org/content/10.1101/2025.02.12.637829v1.full.pdf

#H5N1 #birdFlu #influenza #fluIsAirborne #influenzaIsAirborne #respiratoryDiseasesAreAirborne

So H5N1 really must be airborne?! 💨

Were the birds not at other risk?
👉 These chickens are kept at "the highest biosecurity standards." ⛓️🔒⛓️

[1] Ok but maybe humans broke the rules?
👉 there was a "complete absence of any interaction between the companies, even through third parties involved in feed replenishment, waste disposal or the transport of carcasses to rendering plants. All farms used their own well water supplies. In addition, the employees were not allowed to keep their own poultry. Therefore, in view of the biosecurity measures in place, the possibility of human-associated secondary spread [...] can be excluded."

[1] Wouldn't different caged birds 🐔 have different exposures to outside air though?
👉 "It is noteworthy that in the affected houses, the infection and subsequent mortality started in the areas closest to the air inlets"

[1] 8km long transmission though? Wouldn't that require the wind to line up just right?
👉 temperatures were 🌡️ warm and stable, keeping between 6°C and 11 °C, and "conditions were remarkable [...] with continuous wind from the west or southwest (250-300 degrees), [...] at the highest wind speeds [...] enabling the virus to reach [downstream birds] within 13-22 min"

[1] Was it even really the same disease, for sure?
👉 "genetic identity ✔️ between the H5N1 strains in the donor and recipient farms"

[1] Maybe it got in sooooome other way?
👉 "all possible alternative routes of infection during this period were excluded by our 🕵️ field investigation."

[1] but another result found no influenza in the air!
👉 "the failure to detect IAV particles away from infected farms must not be taken as evidence of the infeasibility of windborne spread. Indeed, when sampling was correlated with careful estimation of wind direction, IAV particles were detected in air collected up to 1.5 and 2.1 km from affected farms, indicating true wind-mediated dispersal."

5/5 🧵about [1] https://www.biorxiv.org/content/10.1101/2025.02.12.637829v1.full.pdf

#H5N1 #birdFlu #influenza #fluIsAirborne #influenzaIsAirborne #windborne #windborneTransmission