T-cell responses to SARS CoV-2 in unexposed South African women

A potential explanation for the fact that the high force of infection for SARS-CoV-2 in South Africa did not translate into high rates of severe illness and death, may be the presence of cross-reactive immunity induced by common cold coronaviruses (CCoV). We used SARS-CoV-2 peptide pools and whole virus antigen to stimulate peripheral blood mononuclear cells collected pre-2020 from South African women and measured interferon gamma (IFNγ) and interleukin 2 (IL2) production. IFNγ responses were observed in 29.9% of the women and IL2 among 39.2%. Overall, 51.6% of women demonstrated response to at least one stimulant. The responses to SARS-CoV-2 might have been induced by past exposure to CCoV.