Most adults examined in a recent study have pre-existing antibody reactivity to SARS-CoV-2, even if they haven’t had COVID-19. Interestingly, the research by Majdoubi, Michalski et al demonstrated the existence of these cross-reactive antibodies as far back as May 2020. From the abstract:
“Using a highly sensitive multiplex assay and positive/negative thresholds established in infants in whom maternal antibodies have waned, we determined that more than 90% of uninfected adults showed antibody reactivity against the spike protein, receptor-binding domain (RBD), N-terminal domain (NTD), or the nucleocapsid (N) protein from SARS-CoV-2.”
“We conclude that most adults display preexisting antibody cross-reactivity against SARS-CoV-2, which further supports investigation of how this may impact the clinical severity of COVID-19 or SARS-CoV-2 vaccine responses.“
