https://www.nature.com/articles/438406b
This is from 2005
China claims to be well on the way towards vaccinating every domestic bird in the country against avian flu. The bold scheme — which would mean inoculating some 14 billion birds — was announced on 15 November and comes in response to outbreaks that animal-health officials say are dangerously widespread. On 16 November, China confirmed its first two human cases of bird flu, one of which was fatal.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8327827/
A new strain developed in 2013 and was essentially eradicated by developing a new vaccine for the birds.
Why aren't we doing so in the US??? We have an effective vaccine!
https://www.vox.com/future-perfect/24155545/bird-flu-vaccines-h5n1-avian-flu-cows
However, despite seemingly having an effective vaccine in hand, as of late April, the USDA is still not pursuing bird flu vaccination as a disease control strategy. “While USDA is exploring the possibility of developing a poultry H5N1 vaccine to stock and use in an emergency, we are not moving forward with a HPAI vaccination program at this time,”
The biggest sticking point is around trade. The US exported more than $5 billion in poultry meat and products on average every year for the past three years. The USDA enters into trade agreements with each individual country it trades with, explained Upali Galketi Aratchilage, a senior economist at the Food and Agriculture Organization of the United Nations. Each agreement outlines specific biosafety and production requirements that both countries agree to follow. The USDA said, in an email to Vox, that many of those agreements do not allow bird flu vaccination.
Every single bird that is infected gives the virus another million chances to mutate into something 100x worse than COVID. And we are not doing it because of the fucking cost to GDP.
The claim was that "our dirty vaccines" caused not just COVID-19 to be as severe as it is but also its predecessor SARS and the similar virus MERS. I guess it's a mix of both, but given this was as early as 4 March 2020, I wouldn't be surprised if someone has seriously proposed the bird vaccine theory by now.