Highly Effective Naturally Acquired Protection Against COVID-19 Persists for at Least 1 Year: A Meta-Analysis
Abstract
The current massive COVID-19 immunization campaign has initiated a change in the course of the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The duration of postvaccination protection can be estimated from longer-term monitoring of the persistence of naturally acquired protection (since November 2019).
Therefore, this rapid meta-analysis was conducted to evaluate the reinfection rates in post-COVID-19 patients as the primary endpoint to predict protection not only in the general population but also in vulnerable long-term care (LTC) recipients. Methods A search of the relevant literature was carried out in the MEDLINE, EMBASE, Web of Science, MedRxiv, and BioRxiv databases on June 7 and August 20, 2021, to identify any original studies on reinfections in post-COVID-19 patients.
Eligible studies had to include the measure of association of acquired SARS-CoV-2 infection in post-COVID-19 individuals with previously uninfected ones. Key findings [ie, numbers of infected and reinfected individuals, measures of association including the 95% confidence intervals (95% CIs), viral variant of concern, follow-up period of >=180 days, etc] were extracted.
This was a rapid and pragmatic meta-analysis to estimate reduction in the risk of reinfection in post-COVID-19 patients, expressed by the efficacy of naturally acquired protection, that is, (1 - measure of association) x 100%. Given the nonhomogeneity of the studies identified, the outcome was assessed using the random effects model (DerSimonian-Laird method).
Analysis were performed using Stata, version 17 (StataCorp, College Station, TX), at a significance level of α = 0.05 with a 2-tailed 95% CI. The protocol of this study was not registered.