Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Nov 9:9:1023507.
doi: 10.3389/fmed.2022.1023507. eCollection 2022.

COVID-19 vaccines reduce the risk of SARS-CoV-2 reinfection and hospitalization: Meta-analysis

Maria Elena Flacco  1 , Cecilia Acuti Martellucci  1 , Valentina Baccolini  2 , Corrado De Vito  2 , Erika Renzi  2 , Paolo Villari  2 , Lamberto Manzoli  3
Affiliations

COVID-19 vaccines reduce the risk of SARS-CoV-2 reinfection and hospitalization: Meta-analysis

Maria Elena Flacco et al. Front Med (Lausanne). .

Abstract

The addictive protection against SARS-CoV-2 reinfection conferred by vaccination, as compared to natural immunity alone, remains to be quantified. We thus carried out a meta-analysis to summarize the existing evidence on the association between SARS-CoV-2 vaccination and the risk of reinfection and disease. We searched MedLine, Scopus and preprint repositories up to July 31, 2022, to retrieve cohort or case-control studies comparing the risk of SARS-CoV-2 reinfection or severe/critical COVID-19 among vaccinated vs. unvaccinated subjects, recovered from a primary episode. Data were combined using a generic inverse-variance approach. Eighteen studies, enrolling 18,132,192 individuals, were included. As compared to the unvaccinated, vaccinated subjects showed a significantly lower likelihood of reinfection (summary Odds Ratio-OR: 0.47; 95% CI: 0.42-0.54). Notably, the results did not change up to 12 months of follow-up, by number of vaccine doses, in studies that adjusted for potential confounders, adopting different reinfection definitions, and with different predominant strains. Once reinfected, vaccinated subjects were also significantly less likely to develop a severe disease (OR: 0.45; 95% CI: 0.38-0.54). Although further studies on the long-term persistence of protection, under the challenge of the new circulating variants, are clearly needed, the present meta-analysis provides solid evidence of a stronger protection of hybrid vs. natural immunity, which may persist during Omicron waves and up to 12 months.

Keywords: COVID-19; Omicron (B.1.1.529); SARS-CoV-2; meta-analysis; reinfection; vaccination.

PubMed Disclaimer

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Risk of SARS-CoV-2 reinfection among vaccinated vs. unvaccinated subjects.
FIGURE 2
FIGURE 2
Risk of severe/lethal COVID-19 among vaccinated vs. unvaccinated subjects.
See this image and copyright information in PMC

References

    1. European Centre for Disease Prevention and Control. Reinfection with SARS-CoV-2: Considerations for Public Health Response. Stockholm: ECDC; (2020).
    1. Flacco ME, Acuti Martellucci C, Baccolini V, De Vito C, Renzi E, Villari P, et al. Risk of reinfection and disease after SARS-CoV-2 primary infection: meta-analysis. Eur J Clin Invest. (2022) 52:e13845. 10.1111/eci.13845 - DOI - PMC - PubMed
    1. Yahav D, Yelin D, Eckerle I, Eberhardt CS, Wang J, Cao B, et al. Definitions for coronavirus disease 2019 reinfection, relapse and PCR re-positivity. Clin Microbiol Infect. (2021) 27:315–8. 10.1016/j.cmi.2020.11.028 - DOI - PMC - PubMed
    1. Medic S, Anastassopoulou C, Lozanov-Crvenkovic Z, Vukovic V, Dragnic N, Petrovic V, et al. Risk and severity of SARS-CoV-2 reinfections during 2020-2022 in Vojvodina, Serbia: a population-level observational study. Lancet Reg Health Eur. (2022) 20:100453. 10.1016/j.lanepe.2022.100453 - DOI - PMC - PubMed
    1. World Health Organization. Interim Statement on Hybrid Immunity and Increasing Population Seroprevalence Rates. Geneva: World Health Organization; (2022).

Publication types