Influenza Vaccine Effectiveness for Prevention of Severe Influenza-Associated Illness Among Adults in the United States, 2019-2020: A Test-Negative Study. Academic Article uri icon

Overview

abstract

  • BACKGROUND: Influenza vaccine effectiveness (VE) against a spectrum of severe disease, including critical illness and death, remains poorly characterized. METHODS: We conducted a test-negative study in an intensive care unit (ICU) network at 10 US hospitals to evaluate VE for preventing influenza-associated severe acute respiratory infection (SARI) during the 2019-2020 season, which was characterized by circulation of drifted A/H1N1 and B-lineage viruses. Cases were adults hospitalized in the ICU and a targeted number outside the ICU (to capture a spectrum of severity) with laboratory-confirmed, influenza-associated SARI. Test-negative controls were frequency-matched based on hospital, timing of admission, and care location (ICU vs non-ICU). Estimates were adjusted for age, comorbidities, and other confounders. RESULTS: Among 638 patients, the median (interquartile) age was 57 (44-68) years; 286 (44.8%) patients were treated in the ICU and 42 (6.6%) died during hospitalization. Forty-five percent of cases and 61% of controls were vaccinated, which resulted in an overall VE of 32% (95% CI: 2-53%), including 28% (-9% to 52%) against influenza A and 52% (13-74%) against influenza B. VE was higher in adults 18-49 years old (62%; 95% CI: 27-81%) than those aged 50-64 years (20%; -48% to 57%) and ≥65 years old (-3%; 95% CI: -97% to 46%) (P = .0789 for interaction). VE was significantly higher against influenza-associated death (80%; 95% CI: 4-96%) than nonfatal influenza illness. CONCLUSIONS: During a season with drifted viruses, vaccination reduced severe influenza-associated illness among adults by 32%. VE was high among young adults.

authors

  • Grijalva, Carlos G
  • Feldstein, Leora R
  • Talbot, H Keipp
  • Aboodi, Michael
  • Baughman, Adrienne H
  • Brown, Samuel M
  • Casey, Jonathan D
  • Erickson, Heidi L
  • Exline, Matthew C
  • Files, D Clark
  • Gibbs, Kevin W
  • Ginde, Adit A
  • Gong, Michelle N
  • Halasa, Natasha
  • Khan, Akram
  • Lindsell, Christopher J
  • Nwosu, Samuel K
  • Peltan, Ithan D
  • Prekker, Matthew E
  • Rice, Todd W
  • Shapiro, Nathan I
  • Steingrub, Jay
  • Stubblefield, William B
  • Tenforde, Mark W
  • Patel, Manish
  • Self, Wesley H

publication date

  • October 20, 2021

Research

keywords

  • Influenza A Virus, H1N1 Subtype
  • Influenza Vaccines
  • Influenza, Human

Identity

PubMed Central ID

  • PMC8682606

Scopus Document Identifier

  • 85112070042

Digital Object Identifier (DOI)

  • 10.2807/1560-7917

PubMed ID

  • 34014274

Additional Document Info

volume

  • 73

issue

  • 8