Relative vaccine effectiveness of MF59-adjuvanted vs high-dose trivalent inactivated influenza vaccines for prevention of test-confirmed influenza hospitalizations during the 2017–2020 influenza seasons

Abstract

Objectives: This study evaluated relative vaccine effectiveness (rVE) of MF59-adjuvanted trivalent inactivated influenza vaccine (aTIV) vs high-dose trivalent inactivated influenza vaccine (HD-TIV) for prevention of test-confirmed influenza emergency department visits and/or inpatient admissions (“ED/IP”) and for IP admissions alone pooled across the 2017–2020 influenza seasons. Exploratory individual season analyses were also performed. Methods: This retrospective test-negative design study included United States (US) adults age ≥65 years vaccinated with aTIV or HD-TIV who presented to an ED or IP setting with acute respiratory or febrile illness during the 2017–2020 influenza seasons. Test-positive cases and test-negative controls were grouped by vaccine received. The rVE of aTIV vs HD-TIV was evaluated using a combination of inverse probability of treatment weighting and logistic regression to adjust for potential confounders. Results: Pooled analyses over the three seasons found no significant differences in the rVE of aTIV vs HD-TIV for prevention of test-confirmed influenza ED/IP (−2.5% [−19.6, 12.2]) visits and admissions or IP admissions alone (−1.6% [−22.5, 15.7]). The exploratory individual season analyses also showed no significant differences. Conclusions: Evidence from the 2017–2020 influenza seasons indicates aTIV and HD-TIV are comparable for prevention of test-confirmed influenza ED/IP visits in US adults age ≥65 years.

Keywords

• Adjuvanted influenza vaccine
• Influenza
• Hospitalizations
• High-dose influenza vaccine
• Older adults
• Relative vaccine effectiveness