CITF-funded researcher Dr. Pascal Lavoie from the University of British Columbia and his collaborators are suggesting that the presence of antibodies to SARS-CoV-2 may not necessarily indicate a previous infection. Using highly sensitive tests, they discovered pre-existing antibodies to SARS-CoV-2 in many uninfected adults. The study was funded in part by the COVID-19 Immunity Task Force (CITF).


Since the beginning of the COVID-19 pandemic, researchers have been puzzled as to why some people who are exposed to SARS-CoV-2 develop a mild infection whereas others become severely ill and end up in the intensive care unit. Possible explanations include genetics, age, underlying health conditions, and the amount of virus they were exposed to. In this study, Dr. Lavoie and his collaborators demonstrate that individuals unexposed to SARS-CoV-2 can have antibodies from exposure to seasonal coronaviruses which could explain the wide spectrum of COVID-19 illness.

The research team tested blood samples of 276 people, mostly healthcare workers, between May 17th and June 19th, 2020 in the Greater Vancouver area. Using highly sensitive tests, they found that only 0.6% of adults had antibodies that suggest exposure to SARS-CoV-2. Interestingly, more than 90% of adults were found to have lower, but detectable antibodies, that also happen to target SARS-CoV-2. These antibodies were possibly caused by seasonal coronaviruses. Blood obtained from adults pre-pandemic showed similar antibodies, demonstrating that antibodies against SARS-CoV-2 were already present in some people prior to the start of the pandemic.

The authors conclude that many uninfected adults have antibodies against SARS-CoV-2. Further studies are still required to determine if pre-existing antibodies against seasonal coronaviruses can protect against SARS-CoV-2.


Majdoubi A, Michalski C, O’Connell SE, Dada S, Narpala S, Gelinas J, Mehta D, Cheung C, Winkler D, Basappa M, Liu  AC, Görges M, Barakauska VE, Irvine M, Mehalko J, Esposito D, Sekirov I, Jassem AN, Goldfarb DM, Pelech S, Douek DC, McDermott AB, Lavoie PM. A majority of uninfected adults show pre-existing antibody reactivity against SARS-CoV-2. JCI Insight. 2021. DOI: 10.1172/jci.insight.146316.