Unfortunately, you backyard flock is not protected. It's airborne, is suspected to be infectious up to 5km between farm sites, and also can be contracted via fomite transmission. I hate to be the bearer of bad news, but your birds will likely get infected at some point in the coming 18 months, or sooner, and can be a real attack vector for something nasty for you and your family. The latest mutation across herds in Nevada/Canada both in birds and cows has a real nasty adaptation (D1.1) which has a suspected mortality rate in humans around 50%. Several hospitalizations in humans related to this specific mutation, acquired by individuals dealing with backyard flocks. The logic that your backyard flock mesh is sufficient to protect the flock and you from this pretty nasty bug isn't supported by the evidence we're seeing pan out across the country/world.

Another worrisome attack vector is cats, but that's a whole other pandoras box we'll leave alone for now.

To get an idea of how transmissible/infectious this thing is, it has jumped from birds in Asia, to dolphins in florida, and has eradicated entire populations of seals in latin america, cows, cats, ferrets, rats globally, to almost all bird populations in Antarctica. There is no species / geographic radius that will likely to unaffected. The death rate in each species may vary considerably (cows in US as an example, don't seem to die in great numbers), but it is highly transmissible even between species.

I'm sorry these aren't the best sources, but I'm in a rush and wanted to help you get an idea of what we're dealign with here in the context of your backyard flock, specifically. If you keep digging in all of the themes above you'll find even better sources:

https://www.usnews.com/news/health-news/articles/2025-02-20/...

https://scar.org/library-data/avian-flu

https://www.cdc.gov/media/releases/2024/m1218-h5n1-flu.html

https://www.nature.com/articles/s42003-024-06173-x

https://www.nature.com/articles/s42003-024-06173-x

https://www.vetmed.ucdavis.edu/news/catastrophic-mortality-e...