Effectiveness of the BNT162b2 Vaccine after Recovery from Covid-19

Abstract

Background The risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) decreases substantially among patients who have recovered from coronavirus disease 2019 (Covid-19). However, it is unknown how long protective immunity lasts. Current guidelines recommend vaccination of recovered patients even though data regarding vaccine effectiveness in such cases are still limited. Methods In this retrospective cohort study, we reviewed electronic medical records from a large health care organization in Israel to assess reinfection rates in patients who had recovered from SARS-CoV-2 infection before any vaccination against Covid-19. We compared reinfection rates among patients who had subsequently received the BNT162b2 vaccine (Pfizer–BioNTech) and those who had not been vaccinated between March 1 and November 26, 2021. We used a Cox proportional-hazards regression model with time-dependent covariates to estimate the association between vaccination and reinfection after adjustment for demographic factors and coexisting illnesses. Vaccine effectiveness was estimated as 1 minus the hazard ratio. In a secondary analysis, we evaluated the vaccine effectiveness of one dose as compared with two doses. Results A total of 149,032 patients who had recovered from SARS-CoV-2 infection met the eligibility criteria. Of these patients, 83,356 (56%) received subsequent vaccination during the 270-day study period. Reinfection occurred in 354 of the vaccinated patients (2.46 cases per 100,000 persons per day) and in 2168 of 65,676 unvaccinated patients (10.21 cases per 100,000 persons per day). Vaccine effectiveness was estimated at 82% (95% confidence interval [CI], 80 to 84) among patients who were 16 to 64 years of age and 60% (95% CI, 36 to 76) among those 65 years of age or older. No significant difference in vaccine effectiveness was found for one dose as compared with two doses. Conclusions Among patients who had recovered from Covid-19, the receipt of at least one dose of the BNT162b2 vaccine was associated with a significantly lower risk of recurrent infection.

The S-Trimer (SCB-2019) COVID-19 vaccine and reinfection with SARS-CoV-2

“…Administration of one dose of SCB-2019 in participants who had been pre-exposed to SARS-CoV-2 led to additional vaccine efficacy of 49·9% (1·5–75·6) against any symptomatic COVID-19, and two doses led to additional vaccine efficacy of 64·2% (26·5–83·8). The results reported by Clemens and colleagues were consistent with those found in a previous retrospective cohort study 5 of mRNA vaccine BNT162b2 (Pfizer-BioNTech) in patients who had recovered from SARS-CoV-2 infection.…”

Protection against Omicron re-infection conferred by prior heterologous SARS-CoV-2 infection, with and without mRNA vaccination

“…Immunogenicity studies conducted during the pre-Omicron period show a single BNT162b2 vaccine dose among previously-infected individuals elicited robust antibody and T cell responses, exceeding two-dose response in the infectionnaïve. [31][32][33][34] In epidemiological studies conducted pre-Omicron, one or two BNT162b2 doses in Israel reduced the pre-Omicron re-infection risk by ~80% compared to unvaccinated, previously-infected individuals, 35,36 and in the United Kingdom hybrid protection relative to unvaccinated, previously-uninfected individuals exceeded 90% for >1 year. 14 In Sweden, one-and two-dose hybrid protection reduced the pre-Omicron re-infection risk by 58% and 66%, persisting up to 9 months for the latter, compared to unvaccinated, previously-infected individuals.…”

Added Benefit of Covid-19 Vaccination after Previous Infection

“… 1-4 However, little is known about how much protection is gained by vaccination in previously infected persons. Two studies in this issue of the Journal — one by Hammerman et al 5 and the other by Hall et al 6 — deliver persuasive evidence that among persons with infection-induced immunity, Covid-19 vaccination provides substantial added protection against SARS-CoV-2 reinfection.…”