Age, COVID-19-like symptoms and SARS-CoV-2 seropositivity profiles after the first wave of the pandemic in France.

Background: The interplay between age and symptoms intensity on antibody response to SARS-CoV-2 infection has not been studied in a general population setting.

Methods: We explored the serologic profile of anti-SARS-CoV-2 antibodies after the first wave of the pandemic, by assessing IgG against the spike protein (ELISA-S), IgG against the nucleocapsid protein (ELISA-NP) and neutralizing antibodies (SN) in 82,126 adults from a French population-based multi-cohort study.

Results: ELISA-S positivity was increased in 30- to 49-year-old adults (8.5%) compared to other age groups (5.6% in 20- to 29-year-olds, 2.8% in ≥ 50-year-olds). In the 3681 ELISA-S positive participants, ELISA-NP and SN positivity exhibited a U-shaped relationship with age, with a lower rate in 30- to 49-year-old adults, and was strongly associated with COVID-19-like symptoms.

Conclusion: Our study confirms the independent role of age and symptoms on the serologic profile of anti-SARS-CoV-2 antibodies, but the non-linear relationship with age deserves further investigation.