Increased risk of SARS-CoV-2 reinfection associated with emergence of Omicron in South Africa

Abstract

Here, we provide two methods for monitoring reinfection trends in routine surveillance data to identify signatures of changes in reinfection risk and apply these approaches to data from South Africa’s SARS-CoV-2 epidemic to date. While we found no evidence of increased reinfection risk associated with circulation of Beta (B.1.351) or Delta (B.1.617.2) variants, we find clear, population-level evidence to suggest immune evasion by the Omicron (B.1.1.529) variant in previously infected individuals in South Africa. Reinfections occurring between 01 November 2021 and 31 January 2022 were detected in individuals infected in all three previous waves, and there has been an increase in the risk of having a third infection since mid-November 2021.

Update on SARS-CoV-2 Omicron Variant of Concern and Its Peculiar Mutational Profile

“…Based on epidemiological evidence, it has been estimated that the Omicron VOC is characterized by a 2- to 3-fold increased risk of reinfection, suggesting its capability to evade preexisting immunity ( 7 ). Interestingly, several of the latest studies have shown that the Omicron VOC determines to a different extent the reduction in antibody neutralization elicited by the two doses of the BNT162b2, ChAdOx1, or CoronaVac vaccines compared to the ancestral strain harboring the D614G mutation and to other preexistent variants such as Alpha and Delta ( 8 – 12 ).…”

Boosting of serum neutralizing activity against the Omicron variant among recovered COVID-19 patients by BNT162b2 and CoronaVac vaccines

“…26 , 27 A retrospective analysis in South Africa showed that the Omicron variant was associated with an increased risk of reinfection. 28 …”

SARS-CoV-2: from herd immunity to hybrid immunity

“…In a household study conducted in South Africa, prior infection with Beta and Delta was 93% (95% CI 85–96%) protective against reinfection for the first 3 months and decreased only marginally to 87% (95% CI 79–93%) after 9 months 6 . Omicron, however, was subsequently shown to have a much higher propensity for reinfection than any previous VOC 7 , indicating that infection alone will not produce robust, enduring pan-variant immunity.…”