Santa Casa de Misericordia de Porto Alegre, Porto Alegre, Brazil.
Universidade Federal de Ciencias da Saude de Porto Alegre, UFCSPA, Porto Alegre, Brazil.
PLoS One. 2021 Apr 22;16(4):e0249672. doi: 10.1371/journal.pone.0249672. eCollection 2021.
Limited data is available regarding the frequency of COVID-19 in populations that are highly exposed to SARS-CoV-2. In this cross-section study we evaluated COVID-19 seroprevalence in military police forces of 10 major cities in Rio Grande do Sul, South of Brazil.
Sampling was randomly performed in clusters, in respect to the number of professionals at service per city and military unit. Research subjects were evaluated on July 23, 2020 (first wave peak in Brazil). Clinical information was obtained, and venous blood was taken for ELISA testing (IgA, and IgG antibodies). Sample size consisted of 1,592 military workers (33.6% of study population). They were mostly man (81.2%) and young (median 34 years-old). Most had been asymptomatic (75.3%) during pandemic, and 27.5% reported close contact with COVID-19 cases (after a median time of 21 days). Antibodies were detected in 3.3% of the participants, mostly IgA (2.7%), and IgG (1.7%). After 3 weeks, 66.7% of IgA and IgG results turned negative, in addition to 78.3% and 100% of borderline IgA and IgG results, respectively.
The seroprevalence of COVID-19 amongst military police was at least 3.4 higher than the findings of other studies performed in the general population, in the same cities and dates. Most detectable antibodies were of IgA class, which implies recent exposure. Asymptomatic people were more prone to have negative antibody titters in the second run.
关于高度暴露于 SARS-CoV-2 的人群中 COVID-19 的频率，目前数据有限。在这项横断面研究中，我们评估了巴西南里奥格兰德州 10 个主要城市的宪兵部队中的 COVID-19 血清流行率。
采样是在集群中随机进行的，以每个城市和军事单位的服务专业人员数量为依据。研究对象于 2020 年 7 月 23 日（巴西第一波高峰）进行评估。收集临床信息，并采集静脉血进行 ELISA 检测（IgA 和 IgG 抗体）。样本量由 1592 名军人组成（研究人群的 33.6%）。他们主要是男性（81.2%）和年轻人（中位数 34 岁）。大多数人在大流行期间无症状（75.3%），27.5%报告与 COVID-19 病例有密切接触（中位数时间为 21 天）。3.3%的参与者检测到抗体，主要是 IgA（2.7%）和 IgG（1.7%）。3 周后，IgA 和 IgG 的结果有 66.7%转为阴性，边界值 IgA 和 IgG 的结果分别有 78.3%和 100%转为阴性。
在同一城市和日期，与其他在普通人群中进行的研究相比，宪兵的 COVID-19 血清流行率至少高出 3.4 倍。大多数可检测到的抗体为 IgA 类，表明近期暴露。在第二轮中，无症状者更有可能出现抗体滴度阴性。
