WHO international standard for SARS-CoV-2 antibodies to determine markers of protection

Abstract

Several studies have shown that neutralising antibody level is a good biomarker for the correlate of protection against SARS-CoV-2 infection.1–3 However, results from these studies are presented using assays that have not been calibrated using a common reference standard, making it difficult to define the exact level of neutralising antibodies required for protection and to compare with current and future studies. The most recent study4 is the only one we have identified that reports the neutralising antibody level using WHO international units by calibrating their neutralisation assays against the WHO international standard for SARS-CoV-2 immunoglobulin; the international standard was established by the WHO Expert Committee on Biological Standardization as a primary calibrant to harmonise the measurement of anti-SARS-CoV-2 antibodies and was made available in December, 2020 from the WHO Collaborative centre, the National Institute for Biological Standards and Control (NIBSC), UK.