Abstract
The COVID-19 pandemic is still posing a devastating threat to social life and economics. Despite the modest decrease in the number of cases during September–November 2020, the number of active cases is on the rise again. This increase was associated with the emergence and spread of the new SARS-CoV-2 variants of concern (VOCs), such as the U.K. (B1.1.7), South Africa (B1.351), Brazil (P1), and Indian (B1.617.2) strains. The rapid spread of these new variants has raised concerns about the multiple waves of infections and the effectiveness of available vaccines. In this review, we discuss SARS-CoV-2 reinfection rates in previously infected and vaccinated individuals in relation to humoral responses. Overall, a limited number of reinfection cases have been reported worldwide, suggesting long protective immunity. Most reinfected patients were asymptomatic during the second episode of infection. Reinfection was attributed to several viral and/or host factors, including (i) underlying immunological comorbidities; (ii) low antibody titers due to the primary infection or vaccination; (iii) rapid decline in antibody response after infection or vaccination; and (iv) reinfection with a different SARS-CoV-2 variant/lineage. Infections after vaccination were also reported on several occasions, but mostly associated with mild or no symptoms. Overall, findings suggest that infection- and vaccine-induced immunity would protect from severe illness, with the vaccine being effective against most VOCs.
Highlights
In December 2020, new SARS-CoV-2 variants (B.1.1.7 in the United Kingdom, B.1.351 in South Africa) emerged and led to an unexpected rise in COVID-19 cases [1,2]
According to the Centers for Disease Control and Prevention (CDC) guidelines, SARS-CoV-2 reinfection is identified and confirmed if: (1) viral RNA is identified at two different time points; (2) intervening negative
We summarize the reinfection cases reported along with the humoral responses against SARS-CoV-2, with the aim of developing a better understanding of the causes of reinfection as well as the implications on vaccines
Summary
In December 2020, new SARS-CoV-2 variants (B.1.1.7 in the United Kingdom, B.1.351 in South Africa) emerged and led to an unexpected rise in COVID-19 cases [1,2]. Both variants contained an N501Y mutation in the receptor-binding domain (RBD) of the spike (S) protein, accounting for the increased transmission and infectiousness (40–70%) of the virus [1,2]. Rare cases of prolonged viral shedding (>1 month) have been reported [6,7], including a pregnant woman who remained SARS-CoV-2-positive for 104 days after her initial test [8]. We summarize the reinfection cases reported along with the humoral responses against SARS-CoV-2, with the aim of developing a better understanding of the causes of reinfection as well as the implications on vaccines
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