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. 2022 Jul 8;13(1):3946.
doi: 10.1038/s41467-022-31469-z.

Effectiveness and protection duration of Covid-19 vaccines and previous infection against any SARS-CoV-2 infection in young adults

Lior Rennert  1 , Zichen Ma  2 , Christopher S McMahan  3 , Delphine Dean  4
Affiliations

Effectiveness and protection duration of Covid-19 vaccines and previous infection against any SARS-CoV-2 infection in young adults

Lior Rennert et al. Nat Commun. .

Abstract

Data on effectiveness and protection duration of Covid-19 vaccines and previous infection against general SARS-CoV-2 infection in general populations are limited. Here we evaluate protection from Covid-19 vaccination (primary series) and previous infection in 21,261 university students undergoing repeated surveillance testing between 8/8/2021-12/04/2021, during which B.1.617 (delta) was the dominant SARS-CoV-2 variant. Estimated mRNA-1273, BNT162b2, and AD26.COV2.S effectiveness against any SARS-CoV-2 infection is 75.4% (95% CI: 70.5-79.5), 65.7% (95% CI: 61.1-69.8), and 42.8% (95% CI: 26.1-55.8), respectively. Among previously infected individuals, protection is 72.9% when unvaccinated (95% CI: 66.1-78.4) and increased by 22.1% with full vaccination (95% CI: 15.8-28.7). Statistically significant decline in protection is observed for mRNA-1273 (P < .001), BNT162b2 (P < .001), but not Ad26.CoV2.S (P = 0.40) or previous infection (P = 0.12). mRNA vaccine protection dropped 29.7% (95% CI: 17.9-41.6) six months post- vaccination, from 83.2% to 53.5%. We conclude that the 2-dose mRNA vaccine series initially offers strong protection against general SARS-CoV-2 infection caused by the delta variant in young adults, but protection substantially decreases over time. These findings indicate that vaccinated individuals may still contribute to community spread. While previous SARS-CoV-2 infection consistently provides moderately strong protection against repeat infection from delta, vaccination yields a substantial increase in protection.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Estimated protection from vaccination and previous infection.
Point estimates (with 95% CIs) of (full) vaccine protection among individuals without a previous SARS-CoV-2 infection, vaccine protection among individuals with a previous SARS-CoV-2 infection, and protection from previous infection only. All estimates of protection are relative to individuals with no protection (unvaccinated without a previous SARS-CoV-2 infection).
Fig. 2
Fig. 2. Time-varying protection from mRNA vaccination.
Adjusted estimated vaccine protection (point estimate with 95% CIs) by months since full vaccination for mRNA-1273, BNT162b2, and any mRNA vaccine.
See this image and copyright information in PMC

References

    1. Polack, F. P. et al. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. N. Engl. J. Med.10.1056/NEJMoa2034577 (2020). - PMC - PubMed
    1. Baden LR, et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N. Engl. J. Med. 2021;384:403–416. doi: 10.1056/NEJMoa2035389. - DOI - PMC - PubMed
    1. Sadoff J, et al. Safety and efficacy of single-dose Ad26.COV2.S vaccine against Covid-19. N. Engl. J. Med. 2021;384:2187–2201. doi: 10.1056/NEJMoa2101544. - DOI - PMC - PubMed
    1. Dagan, N. et al. BNT162b2 mRNA Covid-19 vaccine in a Nationwide Mass Vaccination Setting. N. Engl. J. Med. 10.1056/NEJMoa2101765 (2021). - PMC - PubMed
    1. Thompson, M. G. Interim estimates of vaccine effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in preventing SARS-CoV-2 infection among health care personnel, first responders, and other essential and frontline workers —eight U.S. Locations, December 2020–March 2021. MMWR Morb Mortal Wkly Rep. 70. 10.15585/mmwr.mm7013e3 (2021). - PMC - PubMed

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