Better understanding of antibody responses against SARS-CoV-2 after natural infection might provide valuable insights into the future implementation of vaccination policies. Longitudinal analysis of IgG antibody titers was carried out in 32 recovered COVID-19 patients based in the Umbria region of Italy for 14 months after Mild and Moderately-Severe infection.Two FDA-approved immunoassays against SARS-CoV-2 Nucleocapsid protein (NCP) and anti-spike-receptor binding domain (S-RBD) were used for sequential serological tests at different time points. The demographics,clinical history and symptom profile associated with the magnitude and longevity of antibody responses were also analyzed. Anti-S-RBD IgG persisted in 96.8% (31 of 32) subjects at 14 months. Patients reporting loss of smell and taste during the clinical course of the disease developed significantly higher antibody titers. Anti-NCP IgG seronegative patients(n=7) at 10 months, tested positive for anti-S-RBD IgG at 12,13 and 14 months emphasizing on a higher false-negative rate for NCP protein-based antibody assays. This study also highlights the importance of adopting specific immunoassays for routine estimation of antibody titers and the decreased rate of re-infections in recovered patients.

更好地了解自然感染后针对 SARS-CoV-2 的抗体反应可能为未来疫苗接种政策的实施提供有价值的见解。在轻度和中度-重度感染后 14 个月，对意大利翁布里亚地区 32 名康复的 COVID-19 患者进行了 IgG 抗体滴度的纵向分析。FDA 批准的两种针对 SARS-CoV-2 核衣壳蛋白 (NCP) 的免疫测定和抗刺突受体结合域（S-RBD）用于不同时间点的连续血清学测试。还分析了与抗体反应的强度和寿命相关的人口统计学、临床病史和症状概况。抗 S-RBD IgG 在 14 个月时持续存在于 96.8%（32 名中的 31 名）受试者中。在疾病的临床过程中报告嗅觉和味觉丧失的患者产生了显着更高的抗体滴度。抗NCP IgG血清阴性患者（n = 7) 在 10 个月时，在 12、13 和 14 个月时抗 S-RBD IgG 检测呈阳性，强调基于 NCP 蛋白的抗体检测的假阴性率较高。这项研究还强调了采用特异性免疫测定法对抗体滴度进行常规评估以及降低康复患者再感染率的重要性。