My understanding is that each flu season a forecast is made about the strains most likely to be prevalent, and the vaccine is formulated based on this forecast. Is this done exactly once per season, or is the vaccine "updated" if the initial forecast turns out to be inaccurate?
zifzif t1_iwpqgwl wrote
Reply to AskScience AMA Series: We're Experts on Influenza (aka the Flu). AUA! by AskScienceModerator
My understanding is that each flu season a forecast is made about the strains most likely to be prevalent, and the vaccine is formulated based on this forecast. Is this done exactly once per season, or is the vaccine "updated" if the initial forecast turns out to be inaccurate?