Lack of Evidence for Vaccine-Associated Enhanced Disease From COVID-19 Vaccines Among Adults in the Vaccine Safety Datalink

Pharmacoepidemiol Drug Saf. 2024 Aug;33(8):e5863. doi: 10.1002/pds.5863.

Abstract

Purpose: Vaccine-associated enhanced disease (VAED) is a theoretical concern with new vaccines, although trials of authorized vaccines against SARS-CoV-2 have not identified markers for VAED. The purpose of this study was to detect any signals for VAED among adults vaccinated against coronavirus disease 2019 (COVID-19).

Methods: In this cross-sectional study, we assessed COVID-19 severity as a proxy for VAED among 400 adults hospitalized for COVID-19 from March through October 2021 at eight US healthcare systems. Primary outcomes were admission to an intensive care unit (ICU) and severe illness (score ≥6 on the World Health Organization [WHO] Clinical Progression Scale). We compared the risk of outcomes among those who had completed a COVID-19 vaccine primary series versus those who were unvaccinated. We incorporated inverse propensity weights for vaccination status in a doubly robust regression model to estimate the causal average treatment effect.

Results: The causal risk ratio in vaccinated versus unvaccinated was 0.36 (95% confidence interval [CI], 0.15-0.94) for ICU admission and 0.46 (95% CI, 0.25-0.76) for severe illness.

Conclusion: Among hospitalized patients, reduced disease severity in those vaccinated against COVID-19 supports the absence of VAED.

Keywords: COVID‐19 vaccines; SARS‐CoV‐2; vaccine safety; vaccine‐associated enhanced disease.

Publication types

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

MeSH terms

  • Adult
  • Aged
  • COVID-19 Vaccines* / administration & dosage
  • COVID-19 Vaccines* / adverse effects
  • COVID-19* / epidemiology
  • COVID-19* / prevention & control
  • Cross-Sectional Studies
  • Female
  • Hospitalization* / statistics & numerical data
  • Humans
  • Intensive Care Units / statistics & numerical data
  • Male
  • Middle Aged
  • Severity of Illness Index*
  • United States / epidemiology
  • Vaccination / adverse effects

Substances

  • COVID-19 Vaccines