They start making the flu vaccine the year before. It takes six to nine months, and lots of chicken eggs. Here's a Planet Money rerun that talks about how they

They start making the flu vaccine the year before. It takes six to nine months, and lots of chicken eggs. Here's a Planet Money rerun that talks about how they make the regular flu vaccine: https://www.npr.org/2020/03/06/812943907/episode-977-wheres-the-vaccine https://www.npr.org/2020/03/06/812943907/episode-977-wheres-... Transcript: https://www.npr.org/transcripts/812943907 https://www.npr.org/transcripts/812943907