An interesting article published in emerging infectious diseases volume 27, number 1, January 2021 by Galle and others investigated this issue.

They investigated SARS-CoV-2 specific antibodies and T-cell responses against SARS-CoV-2 in 11 SARS-CoV-2 serodiscordant couples in Strasbourg, France.

Interestingly enough, they found that the index patients displayed positive SARS-CoV-2 specific antibody and T-cell responses that lasted up to 102 days after symptom onset.

However, all contacts remained seronegative for SARS-CoV-2.

Although six reported COVID-19 symptoms with a median of seven days after their partners and four showed a positive SARS-CoV-2 specific T-cell response. This lasted up to 93 days after the symptom onset.

This data suggests that exposure to the SARS-CoV-2 virus can induce virus specific T-cell responses without antibody conversion.

This aspect to the immune response against SARS-CoV-2 contributes substantially to the understanding of the natural history of COVID-19 disease.

Furthermore, the data indicates epidemiological data relying solely on the detection of SARS CoV-2 antibody may lead to a substantial underestimation of prior exposure to the virus.

The data also has implications for vaccine development and tracking the future evolution of the SARS-CoV-2 pandemic.

Dr Paul Ettlinger