Introduction Longevity of anti-SARS-CoV-2 antibody level and duration of immunity are current topics of major scientific interest. Antibody kinetics during the acute phase are well-studied, whereas long-term kinetics are yet to be determined and available studies are controversial. Here, results of longitudinal analysis of serological responses to SARS-CoV-2 infection after convalescent and its association with post-COVID syndrome (PCS) are reported. Material and Methods 237 serum samples were prospectively collected from 61 SARS-CoV-2 qRT-PCR-confirmed participants. Anti-SARS-CoV-2 anti-N and anti-RBD/S1 Ig level were serially determined until 8 months after study inclusion. COVID-19 associated symptoms were assessed by a standardized questionnaire at study entry and after 6 months. Results Antibodies were detectable for 56/61 participants. Within the follow-up period, no substantial decline in the anti-SARS-CoV-2 pan-Ig levels were observed. In general, antibody levels were positively correlated with disease severity, BMI, fever, and nonsmoker status. 46.8% of the participants suffered from PCS, with olfactory and gustatory dysfunctions reported most frequently. Conclusion Study result point to stable anti-SARS-CoV-2 antibody titers and thus may indicate a long-lasting immunity. These results are in line with recently published data, and add further insights concerning asymptomatic to mild affected patients, the association with clinical features and the frequency of PCS.

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