COVID-19 reinfections among naturally infected and vaccinated individuals

26, January 2022 |

Authors:

Abstract

The protection against emerging SARS‐CoV‐2 variants by pre‐existing antibodies elicited due to the current vaccination or natural infection is a global concern. We aimed to investigate the rate of SARS‐CoV‐2 infection and its clinical features among infection‐naïve, infected, vaccinated, and post‐ infection‐vaccinated individuals. A cohort was designed among icddr,b staff registered for COVID‐19 testing by real‐time reverse transcriptase‐polymerase chain reaction (rRT‐PCR). Reinfection cases were confirmed by whole‐genome sequencing. From 19 March 2020 to 31 March 2021, 1644 (mean age, 38.4 years and 57% male) participants were enrolled; where 1080 (65.7%) were tested negative and added to the negative cohort. The positive cohort included 750 positive patients (564 from baseline and 186 from negative cohort follow‐up), of whom 27.6% were hospitalized and 2.5% died. Among hospitalized patients, 45.9% had severe to critical disease and 42.5% required oxygen support. Hypertension and diabetes mellitus were found significantly higher among the hospitalised patients compared to out‐patients; risk ratio 1.3 and 1.6 respectively. The risk of infection among positive cohort was 80.2% lower than negative cohort (95% CI 72.6–85.7%; p < 0.001). Genome sequences showed that genetically distinct SARS‐CoV‐2 strains were responsible for reinfections. Naturally infected populations were less likely to be reinfected by SARS‐CoV‐2 than the infection‐naïve and vaccinated individuals. Although, reinfected individuals did not suffer severe disease, a remarkable proportion of naturally infected or vaccinated individuals were (re)‐infected by the emerging variants.