SARS-CoV-2 neutralising antibody testing in Europe: towards harmonisation of neutralising antibody titres for better use of convalescent plasma and comparability of trial data

Nguyen, Dung; Simmonds, Peter; Steenhuis, Maurice; Wouters, Elise; Desmecht, Daniel; Garigliany, Mutien; Romano, Marta; Barbezange, Cyril; Maes, Piet; Van Holm, Bram; Mendoza, Joaquín; Oyonarte, Salvador; Fomsgaard, Anders; Lassaunière, Ria; Zusinaite, Eva; Resman Rus, Katarina; Avšič-Županc, Tatjana; Reimerink, Johan HJ; Brouwer, Fiona; Hoogerwerf, Marieke; Reusken, Chantal BEM; Grodeland, Gunnveig; Le Cam, Sophie; Gallian, Pierre; Amroun, Abdennour; Brisbarre, Nadège; Martinaud, Christophe; Leparc Goffart, Isabelle; Schrezenmeier, Hubert; Feys, Hendrik B; van der Schoot, C Ellen; Harvala, Heli

We compared the performance of SARS-CoV-2 neutralising antibody testing between 12 European laboratories involved in convalescent plasma trials. Raw titres differed almost 100-fold differences between laboratories when blind-testing 15 plasma samples. Calibration of titres in relation to the reference reagent and standard curve obtained by testing a dilution series reduced the inter-laboratory variability ca 10-fold. The harmonisation of neutralising antibody quantification is a vital step towards determining the protective and therapeutic levels of neutralising antibodies.