Breakthrough Infections with SARS-CoV-2 Omicron Variant Despite Booster Dose of mRNA Vaccine

Abstract

Based on its genetic profile and preliminary in vitro and epidemiological data, the recently emerged SARS-CoV-2 Omicron variant is predicted to evade immune responses to some extent. We report a cluster of Omicron variant infections in individuals who had received full primary vaccination series and booster doses with mRNA vaccines. All patients experienced symptomatic COVID-19 but clinical manifestations were mild to moderate. Their SARS-CoV-2 viral RNA loads and anti-spike antibody levels were determined. This series proves that even three doses of mRNA vaccines may not be sufficient to prevent infection and symptomatic disease with the Omicron variant.

Note:
Funding Information: Funding was provided by South African Medical Research Council, Poliomyelitis Research Foundation and National Health Laboratory Service Research Trust

Conflict of Interests: Wolfgang Preiser serves as member of the South African Ministerial Advisory Committee on COVID-19 Vaccines. All other others declare no conflict of interests.

Ethical Approval: The investigation was approved by the Health Research Ethics Committee of Stellenbosch University (REFERENCE NUMBER TO BE INSERTED ONCE AVAILABLE) and all participants provided informed consent.

Keywords: SARS-CoV-2, Omicron variant, B.1.1.529, vaccine breakthrough infection, booster vaccination, COVID-19, mRNA vaccine