Persistence of Anti-SARS-CoV-2 Antibodies in Non-Hospitalized COVID-19 Convalescent Health Care Workers

Margherita Bruni, Valentina Cecatiello, Angelica Diaz-Basabe, Georgia Lattanzi, Erika Mileti, Silvia Monzani, Laura Pirovano, Francesca Rizzelli, Clara Visintin, Giuseppina Bonizzi, Marco Giani, Marialuisa Lavitrano, Silvia Faravelli, Federico Forneris, Flavio Caprioli, Pier Giuseppe Pelicci, Gioacchino Natoli, Sebastiano Pasqualato, Marina Mapelli, Federica Facciotti

Research output: Contribution to journalArticlepeer-review


Although antibody response to SARS-CoV-2 can be detected early during the infection, several outstanding questions remain to be addressed regarding the magnitude and persistence of antibody titer against different viral proteins and their correlation with the strength of the immune response. An ELISA assay has been developed by expressing and purifying the recombinant SARS-CoV-2 Spike Receptor Binding Domain (RBD), Soluble Ectodomain (Spike), and full length Nucleocapsid protein (N). Sera from healthcare workers affected by non-severe COVID-19 were longitudinally collected over four weeks, and compared to sera from patients hospitalized in Intensive Care Units (ICU) and SARS-CoV-2-negative subjects for the presence of IgM, IgG and IgA antibodies as well as soluble pro-inflammatory mediators in the sera. Non-hospitalized subjects showed lower antibody titers and blood pro-inflammatory cytokine profiles as compared to patients in Intensive Care Units (ICU), irrespective of the antibodies tested. Noteworthy, in non-severe COVID-19 infections, antibody titers against RBD and Spike, but not against the N protein, as well as pro-inflammatory cytokines decreased within a month after viral clearance. Thus, rapid decline in antibody titers and in pro-inflammatory cytokines may be a common feature of non-severe SARS-CoV-2 infection, suggesting that antibody-mediated protection against re-infection with SARS-CoV-2 is of short duration. These results suggest caution in using serological testing to estimate the prevalence of SARS-CoV-2 infection in the general population.

Original languageEnglish
Article number3188
JournalJournal of Clinical Medicine
Issue number10
Publication statusPublished - Oct 1 2020


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