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

ObjectivesTo 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 antibody titer. DesignCross-sectional study; 12 months follow-up. SettingResidents in Azienda USL Umbria 2. ParticipantsConsecutive subjects aged 15 to 75 who 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. SARS-CoV-2 serologic testing for antibodies targeting the Nucleocapside and Spike proteins were determined. ResultsOf 184 eligible subjects, 149 were available for evaluation: 17 were classified as Oligo/asymptomatic, 107 as Symptomatic, 25 as Hospital admitted. 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. ConclusionAnti-S and anti-N antibody titers correlates well with disease severity. Anti-S antibodies persist for at least one year and most probably provide protection from reinfection. O_TEXTBOXStrengths and limitations of this study O_LIThe key strength of this study is the evaluation of anti-Sars-Cov-2 serology using two types of serological assays and the follow-up that endured for at least 12 months C_LIO_LIIn addition to serological evaluation participants were also followed-up clinically C_LIO_LIThe study does not have a baseline serologic testing since it was conceived in late April when most of the participants were discharged from hospital or had their symptoms resolved C_LIO_LIThe study lacks clinical and serological information regarding those who died during the pandemic event, hence we are unable to conclude whether quantitative serologic testing could predict survival C_LI C_TEXTBOX