Polvere Immacolata, Parrella Alfredina, Casamassa Giovanna, D'Andrea Silvia, Tizzano Annamaria, Cardinale Gaetano, Voccola Serena, Porcaro Piercarmine, Stilo Romania, Vito Pasquale, Zotti Tiziana
Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, 82100 Benevento, Italy.
Genus Biotech, Università degli Studi del Sannio, 82100 Benevento, Italy.
Diagnostics (Basel). 2021 Mar 9;11(3):483. doi: 10.3390/diagnostics11030483.
SARS-CoV-2 is a zoonotic betacoronavirus associated with worldwide transmission of COVID-19 disease. By the beginning of March, WHO reported about 113,820,000 confirmed cases including more than 2,527,000 deaths all over the world. However, the true extent of virus circulation or its real infection/fatality ratio is not well-estimated due to the huge portion of asymptomatic infections. In this observational study, we have estimated the prevalence of specific immunoglobulin M and G directed towards SARS-CoV-2 antigen in a cohort of 1383 adult volunteers aged over 65 years old, living in the district of Benevento, in the South of Italy. Serological screening was carried out on capillary blood in September 2020, seven months after pandemic outbreak in Italy, to evaluate virus circulation and antibody response among elderly adults, in which severe symptoms due to viral infection are more common. The overall seroprevalence of anti-SARS-CoV-2 antibodies was 4.70% (CI 3.70%-5.95%) with no statistically significant differences between sexes. Among these, 69.69% (CI 55.61%-77.80%) tested positive to IgM, 23.08% (CI 14.51%-34.64%) to IgG and 9.23% (CI 4.30%-18.71%) was positive for both. All patients that were positive to IgM underwent molecular testing through RT-qPCR on oral-rhino pharyngeal swabs and only one specimen was positive for SARS-CoV-2 RNA detection. Instead, the presence of IgG from screened volunteers was confirmed by re-testing serum samples using both an ELISA assay validated for in vitro diagnostic use (IVD) and a recently published synthetic peptide-based ELISA assay. In conclusion, our report suggests that (1) early restrictions were successful in limiting COVID-19 diffusion in the district of Benevento; (2) rapid serological analysis is an ideal testing for both determining real seroprevalence and massive screening, whereas detection of viral RNA remains a gold standard for identification of infected patients; (3) even among people without COVID-19 related symptoms, the antibody response against SARS-CoV-2 antigens has individual features.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）是一种人畜共患的β冠状病毒，与新冠肺炎疾病的全球传播有关。截至3月初，世界卫生组织报告全球确诊病例约1.1382亿例，死亡病例超过252.7万例。然而，由于无症状感染比例巨大，病毒的实际传播范围及其真实感染率/死亡率并未得到准确估计。在这项观察性研究中，我们对意大利南部贝内文托地区1383名65岁以上成年志愿者进行了检测，以评估针对SARS-CoV-2抗原的特异性免疫球蛋白M和G的流行情况。血清学筛查于2020年9月进行，即意大利疫情爆发七个月后，旨在评估老年人中的病毒传播情况和抗体反应，因为病毒感染导致的严重症状在老年人中更为常见。抗SARS-CoV-2抗体的总体血清阳性率为4.70%（置信区间3.70%-5.95%），男女之间无统计学显著差异。其中，69.69%（置信区间55.61%-77.80%）的IgM检测呈阳性，23.08%（置信区间14.51%-34.64%）的IgG检测呈阳性，9.23%（置信区间4.30%-18.71%）两者均呈阳性。所有IgM呈阳性的患者均通过口咽拭子进行逆转录定量聚合酶链反应（RT-qPCR）分子检测，只有一份标本的SARS-CoV-2 RNA检测呈阳性。相反，通过使用经体外诊断用途（IVD）验证的酶联免疫吸附测定（ELISA）和最近发表的基于合成肽的ELISA对血清样本进行重新检测，确认了筛查志愿者中IgG的存在。总之，我们的报告表明：（1）早期限制措施成功地限制了新冠肺炎在贝内文托地区的传播；（2）快速血清学分析是确定实际血清阳性率和大规模筛查的理想检测方法，而病毒RNA检测仍然是识别感染患者的金标准；（3）即使在没有新冠肺炎相关症状的人群中，针对SARS-CoV-2抗原的抗体反应也具有个体特征。
