Long-term persistence of RBD-positive memory B cells encoding neutralising antibodies in SARS-CoV-2 infection

Considerable concerns relating to the duration of protective immunity against SARS-CoV-2 exist, with evidence of antibody titres declining rapidly after infection and reports of reinfection. Here we monitor the antibody responses against SARS-CoV-2 receptor binding domain (RBD) for up to six months after infection. While antibody titres are maintained, about 13% of the cohort's neutralising responses return to background. However, encouragingly in a selected subset of 13 participants, 12 have detectable RBD-specific memory B cells and these generally are increasing out to 6 months. Furthermore, we are able to generate monoclonal antibodies with SARS-CoV-2 neutralising capacity from these memory B cells. Overall our study suggests that the loss of neutralising antibodies in plasma may be countered by the maintenance of neutralising capacity in the memory B cell repertoire.Arunasingam Abayasingam, Harikrishnan Balachandran, David Agapiou, Marianne Martinello, Rowena A. Bull, on Behalf of the COSIN Study Grou