Grijalva CG, Feldstein LR, Talbot HK, Aboodi M, et al. Influenza Vaccine Effectiveness for Prevention of Severe Influenza-Associated
Illness among Adults in the United States, 2019-2020: A test-negative study. Clin Infect Dis 2021 May 20. pii: 6279050. doi: 10.1093.
PMID: 34014274