Relative Effectiveness of Influenza Vaccines Among the United States Elderly, 2018-2019

J Infect Dis. 2020 Jun 29;222(2):278-287. doi: 10.1093/infdis/jiaa080.


Background: Studies among individuals ages ≥65 years have found a moderately higher relative vaccine effectiveness (RVE) for the high-dose (HD) influenza vaccine compared with standard-dose (SD) products for most seasons. Studies during the A(H3N2)-dominated 2017-2018 season showed slightly higher RVE for the cell-cultured vaccine compared with SD egg-based vaccines. We investigated the RVE of influenza vaccines among Medicare beneficiaries ages ≥65 years during the 2018-2019 season.

Methods: This is a retrospective cohort study using inverse probability of treatment weighting and Poisson regression to evaluate RVE in preventing influenza hospital encounters.

Results: Among 12 777 214 beneficiaries, the egg-based adjuvanted (RVE, 7.7%; 95% confidence interval [CI], 3.9%-11.4%) and HD (RVE, 4.9%; 95% CI, 1.7%-8.1%) vaccines were marginally more effective than the egg-based quadrivalent vaccines. The cell-cultured quadrivalent vaccine was not significantly more effective than the egg-based quadrivalent vaccine (RVE, 2.5%; 95% CI, -2.4% to 7.3%).

Conclusions: We did not find major effectiveness differences between licensed vaccines used among the elderly during the 2018-2019 season. Consistent with prior research, we found that the egg-based adjuvanted and HD vaccines were slightly more effective than the egg-based quadrivalent vaccines.

Keywords: cell-cultured vaccine; high-dose vaccine; influenza vaccine; vaccine effectiveness.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adjuvants, Immunologic
  • Aged
  • Aged, 80 and over
  • Emergency Service, Hospital
  • Female
  • Hospitalization
  • Humans
  • Influenza A Virus, H3N2 Subtype / immunology
  • Influenza Vaccines / administration & dosage
  • Influenza Vaccines / immunology*
  • Influenza, Human / prevention & control*
  • Male
  • Medicare
  • Retrospective Studies
  • Treatment Outcome
  • United States
  • Vaccines, Combined / administration & dosage
  • Vaccines, Combined / immunology
  • Vaccines, Synthetic / administration & dosage
  • Vaccines, Synthetic / immunology


  • Adjuvants, Immunologic
  • Influenza Vaccines
  • Vaccines, Combined
  • Vaccines, Synthetic