Antibody response to SARS‐CoV‐2 in infected patients with different clinical outcome

Anichini, Gabriele; Gandolfo, Claudia; Terrosi, Chiara; Fabrizi, Simonetta; Miceli, Giovanni Battista; Gori Savellini, Gianni; Prathyumnan, Shibily; Franchi, Federico; Cusi, Maria Grazia

Data regarding antibody responses to severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) in patients infected with COVID‐19 are not yet available. In this study, we aimed to evaluate serum antibody responses in patients regardless of the outcome. We measured the circulating immunoglobulin G (IgG) antibody levels in 60 subjects with a certified history of SARS‐CoV‐2 infection by using immunoenzymatic, chemiluminescent, and Neutralization assays. Half patients had a severe infection, the other half were pauci‐symptomatic. We analyzed their antibody response to see the trend of the humoral response. Our results showed a significant difference in circulating IgG level among the two groups. The neutralizing antibody response against SARS‐CoV‐2 was significantly higher among those who had severe disease. Furthermore, ten subjects from each group were screened twice, and a declining antibody trend was observed in pauci‐symptomatic individuals. These findings provide evidence that humoral immunity against SARS‐CoV‐2 in pauci‐symptomatic people is weak and may not be long‐lasting. This may have implications for immunity strategy and prevention, since it is still not clear whether a time‐dependent decrease of both circulating and neutralizing antibodies to nonprotective levels could occur in a longer time span and whether potential vaccines are able to induce a herd immunity and a durable response.