Two years after it emerged, 'cow flu' is still circulating—and baffling scientists: Researchers still aren't sure how H5N1 influenza spreads between cows and from farm to farm.

The article focuses on the ongoing U.S. outbreak of the H5N1 influenza virus in dairy cattle, which began in 2024 and appears to be waning but remains present in some states. Researchers remain uncertain about the exact transmission routes between cows and farms, with evidence suggesting multiple pathways including airborne spread, contaminated milking equipment, flies, semen, and waste milk. Control measures such as testing, quarantining, and movement restrictions have helped reduce infections, while promising vaccine candidates, including mRNA vaccines, are under development but face regulatory and acceptance challenges. Scientists emphasize the need to use the current decline as an opportunity to advance vaccination and prevention efforts to avoid resurgence. [Extracted from the article]