A majority of uninfected adults show preexisting antibody reactivity against SARS-CoV-2

• DOI: 10.1172/jci.insight.146316
• Publication Date: 2021-03-15T16:00:56Z
• Authors: Abdelilah Majdoubi; Christina Michalski; Sarah E. O’Connell; Sarah Dada; Sandeep Narpala; Jean Gelinas; Disha Mehta; Claire Cheung; Dirk F.H. Winkler; Manjula Basappa; Aaron C. Liu; Matthias Görges; Vilte E. Barakauskas; Mike Irvine; Jennifer Mehalko; Dominic Esposito; Inna Sekirov; Agatha N. Jassem; David M. Goldfarb; Steven Pelech; Daniel C. Douek; Adrian B. McDermott; Pascal M. Lavoie
• Keywords: Multiplex; Cross-reactivity; Coronavirus

Preexisting cross-reactivity to SARS-CoV-2 occurs in the absence of prior viral exposure. However, this has been difficult quantify at population level due a lack reliably defined seroreactivity thresholds. Using an orthogonal antibody testing approach, we estimated that about 0.6% nontriaged adults from greater Vancouver, Canada, area between May 17 and June 19, 2020, showed clear evidence infection, after adjusting for false-positive false-negative test results. highly sensitive multiplex assay positive/negative thresholds established infants whom maternal antibodies have waned, determined more than 90% uninfected reactivity against spike protein, receptor-binding domain (RBD), N-terminal (NTD), or nucleocapsid (N) protein SARS-CoV-2. This was evenly distributed across age sex, correlated with circulating coronaviruses' reactivity, partially outcompeted by soluble spike. custom peptide mapping array, found broadly mapped conserved nonstructural proteins. We conclude most display preexisting SARS-CoV-2, which further supports investigation how may impact clinical severity COVID-19 vaccine responses.