H5N1 has been circulating in birds for years. The reason it is getting more attention now is specific and worth understanding clearly.

The virus crossed into cattle in the US in 2024 — an unexpected host jump that expanded the pool of potential human exposure significantly. Dairy farm workers have tested positive in multiple states. Most cases involved mild illness: eye irritation, respiratory symptoms, rapid recovery. No sustained human-to-human transmission has been documented. That last sentence is the most important one in any bird flu discussion, and it remains true as of now.