Standardised, quantitative neutralisation responses to SARS-CoV-2 Variants of Concern by convalescent anti-sera from first wave infections of UK Health Care Workers and Patients
One of the defining criteria of Variants of Concern (VOC) is their ability to evade pre-existing immunity, increased transmissibility, morbidity and/or mortality. Here we examine the capacity of convalescent plasma, from a well defined cohort of healthcare workers (HCW) and Patients infected during the first wave from a national critical care centre in the UK, to neutralise B.1.1.298 variant and three VOCs; B.1.1.7, B.1.351 and P.1. Furthermore, to enable lab to lab, country to country comparisons we utilised the World Health Organisation (WHO) International Standard for anti-SARS-CoV-2 Immunoglobulin to report neutralisation findings in International Units. These findings demonstrate a significant reduction in the ability of first wave convalescent plasma to neutralise the VOCs. In addition, Patients and HCWs with more severe COVID-19 were found to have higher antibody titres and to neutralise the VOCs more effectively than individuals with milder symptoms. Widespread use of the WHO International Standard by laboratories in different countries will allow for cross-laboratory comparisons, to benchmark and to establish thresholds of protection against SARS-CoV-2 and levels of immunity in different settings and countries.