Antibody response in individuals affected with Sars-Cov-2 infection: temporal trends and qualitative and quantitative differences in symptomatic and asymptomatic subjects. A Cross Sectional Analysis. Ab-Covid Study

Abraha, I.; Germani, A.; Pasquarelli, E.; Pascolini, S.; Antonietti, R.; Argenti, S.; Fioravanti, A.; Martini, E.; Aristei, L.; Mancinelli, P.; Ottaviani, M. L.; Roselli, M.; Barzacca, M.; Belardinelli, E.; Micheli, M.

Objectives To describe clinical characteristics and treatment used in subjects who had Sars-Cov-2 infection during the first pandemic and to assess the correlation between serological titers and clinical characteristics; to evaluate the persistence of anti-Sars-Cov-2 titers over a follow-up of 12. Design Cross-sectional study. Setting Residents in Azienda USL Umbria 2. Participants Consecutive subjects aged 15 to 75 who from February, 2020, to March 2021 were discharged with the diagnosis of Sars-Cov-2 from the hospitals of the AUSL Umbria 2, or resulted positive to a PCR test for Sars-Cov-2 infection with or without symptoms. Participants were classified according to clinical findings. SARS-CoV-2 serologic testing for antibodies targeting the Nucleocapside and Spike proteins were determined. Results Of 184 eligible subjects, 149 were available for evaluation: 17 were classified as Oligo/asymptomatic, 107 as Symptomatic (with no hospital admission), 25 as Hospital. While fever resulted common to all the groups, headache or musculoskeletal pain was common to symptomatic participants whereas cough and dyspnea was present in all the hospital admitted. Participants with significant signs and symptoms were more likely to use antibiotics, hydroxychloroquine, heparin and steroids. Compared to Oligo/asymptomatic participants, Symptomatic and Hospital admitted participants had higher levels of anti-S titers at every follow-up (median titer at 12 month follow-up: 29 vs 94 vs 116 respectively; P < 0.001). At 12 months follow-up, anti-S titers persisted above the threshold for at least 12 months in all Hospital admitted participants, in 90% of the Symptomatic participants and 83% in the oligo/asymptomatic participants; in 30% of participants the titer raised significantly probably due to reinfection. Anti-N antibody titer tended to decrease over time and in 62% of the entire cohort resulted negative. None of the participants reported clinical reinfection with Sars-Cov-2 virus. Conclusion - Anti-S and anti-N antibody titers correlates well with disease severity. While anti-N decline overtime, anti-S antibodies persist for at least one year and most probably provide protection from reinfection.