Seasonal cold infections might generate protective antibodies against COVID-19

[S]easonal coronavirus infections occur frequently and typically result in a mild, common cold-like illness. The presence of these coronavirus infections in the population has led to the hypothesis that immune cross-reactivity among these related viruses could occur, and potentially offer some protection to SARS-CoV-2. Now, a group of scientists has detected preexisting antibody-driven immunity against SARS-CoV-2 in a small proportion of individuals who were uninfected at the time of sampling.

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The London-based group of researchers found that 16 out of 302 adults (5.3%) harbored IgG antibodies that were likely generated during previous seasonal “common cold” coronavirus infections, and which cross-reacted with subunit S2 of the SARS-CoV-2 spike protein complex.

Notably, the presence of these cross-reactive IgG antibodies was much more prevalent in an additional cohort of SARS-CoV-2-uninfected children and adolescents (aged 1 to 16 years): at least 21 of these 48 subjects (43.8%) had detectable levels of SARS-CoV-2 S-reactive IgG antibodies.

Though previous studies suggest cross-reactive immunity is neither sterilizing nor long-lasting, the presence of cross-reactivity can reduce viral transmission and ameliorate symptoms and is, therefore, an important area of study. The authors noted that distinguishing preexisting and de novo immunity “will be critical for our understanding of susceptibility to and the natural course of SARS-CoV-2 infection.”

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