For those who are new to this story let me start back at the beginning, in 1997.
In that year, a child in Hong Kong died of the flu. Doctors shipped a sample of his blood to virus experts in Europe, but they didn’t bother taking a look at it for months. When they did, they were startled to discover that it was unlike any flu they’d seen in a human being before.
Each year, several different flu strains circulate from person to person around the world. They’re known by the initials of the proteins that cover their surface–H3N2, for example, is one common strain. The H stands for haemagglutinin, a protein that latches to a host cell so that the ...