Study: Strong Immune Responses to Harmless Coronaviruses Boosts COVID-19 Immunity

The findings of a new study suggest that previous antibody responses to harmless coronaviruses augments immunity to SARS-CoV-2 (COVID-19). The study was conducted by researchers from the University of Zurich, and published in Nature Communications.

To conduct this analysis, researchers used a specifically developed assay to assess antibody levels against four other human coronaviruses in 825 serum samples, which were taken before the emergence of COVID. They also assessed 389 samples of individuals infected with COVID.

The results demonstrated that people infected with COVID had lower levels of antibodies against coronaviruses that cause common colds compared to uninfected people. Moreover, the investigators found that people with high levels of antibodies against harmless coronaviruses were less likely to require hospitalization following COVID infection, suggesting that building immunity to less dangerous coronaviruses confers a level of protection against SARS-CoV-2. “People who have had strong immune responses to other human coronaviruses also have some protection against SARS-CoV-2 infection,” says Alexandra Trkola, head of the Institute of Medical Virology at UZH via a press release about the study. This type of immune response is referred to as cross-reactivity.

What remains unknown, according to the researchers, is whether this cross-reactivity works in opposite direction. In other words, do people with immunity to COVID – through vaccination or infection – possess enhanced protection against other human coronaviruses? That question needs to be elucidated.

“If SARS-CoV-2 immunity also offers some degree of protection from infection with other coronaviruses, we would be a significant step closer to achieving comprehensive protection against other coronaviruses, including any new variants,” said Dr. Trkola.