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Randomized Controlled Trial
. 2022 May;175(5):674-681.
doi: 10.7326/M21-4130. Epub 2022 Feb 15.

The Incidence of SARS-CoV-2 Reinfection in Persons With Naturally Acquired Immunity With and Without Subsequent Receipt of a Single Dose of BNT162b2 Vaccine : A Retrospective Cohort Study

Sivan Gazit  1 , Roei Shlezinger  2 , Galit Perez  3 , Roni Lotan  3 , Asaf Peretz  4 , Amir Ben-Tov  5 , Esma Herzel  3 , Hillel Alapi  3 , Dani Cohen  6 , Khitam Muhsen  6 , Gabriel Chodick  7 , Tal Patalon  1
Affiliations
Randomized Controlled Trial

The Incidence of SARS-CoV-2 Reinfection in Persons With Naturally Acquired Immunity With and Without Subsequent Receipt of a Single Dose of BNT162b2 Vaccine : A Retrospective Cohort Study

Sivan Gazit et al. Ann Intern Med. 2022 May.

Abstract

Background: There is insufficient evidence regarding the magnitude and durability of protection conferred by a combined effect of naturally acquired immunity after SARS-CoV-2 infection and vaccine-induced immunity.

Objective: To compare the incidence rate of SARS-CoV-2 reinfection in previously infected persons to that of previously infected persons who subsequently received a single dose of BNT162b2 messenger RNA vaccine.

Design: A retrospective cohort study emulating a randomized controlled target trial through a series of nested trials.

Setting: Nationally centralized database of Maccabi Healthcare Services, Israel.

Participants: Persons with documented SARS-CoV-2 infection who did not receive subsequent SARS-CoV-2 vaccination were compared with persons with documented SARS-CoV-2 infection who received a single dose of the BNT162b2 vaccine at least 3 months after infection.

Intervention: Forty-one randomized controlled trials were emulated, in which 107 413 Maccabi Healthcare Services' members aged 16 years and older were eligible for at least 1 trial.

Measurements: SARS-CoV-2-related outcomes of infection, symptomatic disease, hospitalization, and death, between 2 March and 13 December 2021.

Results: A statistically significant decreased risk (hazard ratio, 0.18 [95% CI, 0.15 to 0.20]) for reinfection was found among persons who were previously infected and then vaccinated versus those who were previously infected but remained unvaccinated. In addition, there was a decreased risk for symptomatic disease (hazard ratio, 0.24 [CI, 0.20 to 0.29]) among previously infected and vaccinated persons compared with those who were not vaccinated after infection. No COVID-19-related mortality cases were found.

Limitation: Hybrid protection against non-Delta variants could not be inferred.

Conclusion: Persons previously infected with SARS-CoV-2 gained additional protection against reinfection and COVID-19 from a subsequent single dose of the BNT162b2 vaccine. Nonetheless, even without a subsequent vaccination, reinfection appeared relatively rare.

Primary funding source: None.

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Conflict of interest statement

Disclosures: Authors have reported no disclosures of interest. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M21-4130.

Figures

Visual Abstract.
Visual Abstract.. A Single Dose of BNT162b2 Enhances Naturally Acquired Immunity.
Using a national database in Israel, the incidence rates of SARS-CoV-2 reinfection in persons who were previously infected with SARS-CoV-2 but did not receive subsequent vaccination were compared with the incidence rates of SARS-CoV-2 reinfection in previously infected persons who received a single dose of the BNT162b2 messenger RNA vaccine.
Figure 1.
Figure 1.. Standardized failure curves for SARS-CoV-2 reinfection.
Figure 2.
Figure 2.. Standardized curves for SARS-CoV-2 reinfection.
See this image and copyright information in PMC

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