A pandemic upside: The flu virus became less diverse, simplifying the task of making flu shots
ByHelenBranswellJune2,2021IntheeightyearsleadinguptotheCovid-19pandemic,oneofthesubtypesofinfluenzaAvirusesstartedactingbizarrely.Fluvirusescontinuouslyevolve,toevadetheimmunedefenseshumansdeveloptofe