With reports of the first human death from bird flu in the US, some Americans are feeling an uncomfortable flashback to the early days of Covid-19, when infectious disease experts were talking about a new virus that was sending people to the hospital with respiratory infections.

In early December 2024, a group of researchers published an article in the journal Science, entitled "A single mutation in bovine influenza H5N1 hemagglutinin switches specificity to human receptors".