COVID-19 reinfections among naturally infected and vaccinated individuals

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.

SARS-CoV-2 reinfections with BA.1 (Omicron) variant among fully vaccinated individuals in the northeast of Brazil

“…13 Recent studies have demonstrated that Omicron-infected cases tended to cause mild symptoms such as pharyngitis, headache, nasal [29] which corroborates with our data. Despite the fact that three subjects have a booster, with the third/additional dose, they developed symptomatic COVID-19, as others with complete vaccination and previous history of COVID-19 [7]. These data support the findings that neither the current vaccines available nor previous history of COVID-19 are sufficient to establish a robust response toward the Omicron variant and to promote a reduced risk of infection.…”

“…The dissemination of these variants, so-called variants of concern (VoC), are also closely associated with higher viral load [3], and/or rates of reinfection [4] among individuals. By the fact that VoCs can surpass the protective effects of humoral immunity induced either by natural infection or by vaccination [5,6], this poses an additional challenge to curb the pandemic since the highest number of new cases and an increased number of reinfections still have been reported worldwide in 2022 [7].…”

Post-Vaccination SARS-CoV-2 Infections among Health Workers at the University Hospital of Verona, Italy: A Retrospective Cohort Survey

“…Another aspect of this pandemic regards both reinfections and infections among vaccinated subjects. While, on the one hand, the pandemic growth curve has been significantly reduced, on the other hand, in various health contexts worldwide, cases of reinfection have been detected in subjects previously positive for SARS-CoV-2, along with cases of infection diagnosed in vaccinated subjects (conventionally called "vaccine breakthroug") [14][15][16][17].…”

Dealing with a mucosal viral pandemic: lessons from COVID-19 vaccines

“…It has been observed that IgG concentrations in the serum and lung of patients treated with IgG prevents pulmonary infection, but that IgG diffusion into mucosal membranes of the upper airways is insufficient to prevent sinus infection. Thus, the complementarity between a strong systemic response mediated by IgG in the lung and a mucosal response at infection sites mediated by IgA could explain why a better protection has been observed in individuals who were vaccinated after a previous SARS-CoV-2 infection 86 . Delivered intramuscularly, available SARS-CoV-2 vaccines prevent the development of COVID-19 once the pathogen has crossed mucosal barriers, and mostly result in the systemic production of antibodies and recruitment of T lymphocytes in the lower respiratory tract, but not in the upper respiratory tract.…”