Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy.
Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy; Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy.
EBioMedicine. 2020 Nov;61:103069. doi: 10.1016/j.ebiom.2020.103069. Epub 2020 Oct 22.
Italy was the first western country to experience a large Coronavirus Disease 2019 (COVID-19) outbreak and the province of Bergamo experienced one of the deadliest COVID-19 outbreaks in the world. Following the peak of the epidemic in mid-March, the curve has slowly fallen thanks to the strict lockdown imposed by the Italian government on 9th March 2020.
We performed a cross-sectional study to assess the prevalence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection in 423 workers in Bergamo province who returned to the workplace after the end of the Italian lockdown on 5th May 2020. To this end, we performed an enzyme-linked immunosorbent assay (ELISA) to detect the humoral response against SARS-CoV-2 and a nasopharyngeal swab to assess the presence of SARS-CoV-2 RNA by real-time reverse transcription polymerase chain reaction (rRT-PCR). As a secondary aim of the study, we validated a lateral flow immunochromatography assay (LFIA) for the detection of anti-SARS-CoV-2 antibodies.
ELISA identified 38.5% positive subjects, of whom 51.5% were positive for both IgG and IgM, 47.3% were positive only for IgG, but only 1.2% were positive for IgM alone. Only 23 (5.4%) participants tested positive for SARS-CoV-2 by rRT-PCR, although with high cycle thresholds (between 34 and 39), indicating a very low residual viral load that was not able to infect cultured cells. All these rRT-PCR positive subjects had already experienced seroconversion. When the ELISA was used as the comparator, the estimated specificity and sensitivity of the rapid LFIA for IgG were 98% and 92%, respectively.
the prevalence of SARS-CoV-2 infection in the province of Bergamo reached 38.5%, significantly higher than has been reported for most other regions worldwide. Few nasopharyngeal swabs tested positive in fully recovered subjects, though with a very low SARS-CoV-2 viral load, with implications for infectivity and discharge policies for positive individuals in the post-pandemic period. The rapid LFIA used in this study is a valuable tool for rapid serologic surveillance of COVID-19 for population studies.
The study was supported by Regione Lombardia, Milano Serravalle - Milano Tangenziali S.p.A., Brembo S.p.A, and by MEI System.
意大利是首个遭遇 2019 年冠状病毒病（COVID-19）大流行的西方国家，而贝加莫省经历了全球 COVID-19 死亡率最高的疫情之一。自 3 月中旬疫情高峰以来，由于意大利政府于 2020 年 3 月 9 日实施了严格的封锁措施，疫情曲线已缓慢下降。
我们进行了一项横断面研究，以评估 2020 年 5 月 5 日意大利封锁结束后返回工作岗位的贝加莫省 423 名工人中严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）感染的患病率。为此，我们进行了酶联免疫吸附测定（ELISA）以检测针对 SARS-CoV-2 的体液反应，并通过实时逆转录聚合酶链反应（rRT-PCR）检测鼻咽拭子中 SARS-CoV-2 RNA 的存在。作为研究的次要目的，我们验证了侧向流动免疫层析测定（LFIA）检测抗 SARS-CoV-2 抗体的方法。
ELISA 鉴定出 38.5%的阳性受试者，其中 51.5%的 IgG 和 IgM 均为阳性，47.3%仅 IgG 阳性，但仅 1.2%的 IgM 单独阳性。尽管循环阈值（34-39）较高，但仅 23 名（5.4%）参与者通过 rRT-PCR 检测出 SARS-CoV-2 呈阳性，这表明病毒载量极低，无法感染培养细胞。所有这些 rRT-PCR 阳性的受试者均已发生血清转换。当 ELISA 用作比较时，快速 LFIA 检测 IgG 的估计特异性和敏感性分别为 98%和 92%。
贝加莫省 SARS-CoV-2 感染的患病率达到 38.5%，明显高于世界上大多数其他地区的报告。在已完全康复的受试者中，很少有鼻咽拭子检测呈阳性，但 SARS-CoV-2 病毒载量非常低，这对感染性和阳性个体在大流行后的出院政策具有影响。本研究中使用的快速 LFIA 是 COVID-19 人群研究中快速血清学监测的有价值工具。
该研究得到伦巴第大区、米兰 Serravalle-米兰 Tangenziali S.p.A.、Brembo S.p.A.和 MEI 系统的支持。
