Universidade Federal de Pelotas. Faculdade de Medicina. Programa de Pós-Graduação em Epidemiologia. Pelotas, RS, Brasil.
The Rockefeller University. Laboratory for Lymphocyte Dynamics. New York, NY, USA.
Rev Saude Publica. 2021 Nov 22;55:78. doi: 10.11606/s1518-8787.2021055004075. eCollection 2021.
To describe the evolution of seropositivity in the State of Rio Grande do Sul, Brazil, through 10 consecutive surveys conducted between April 2020 and April 2021.
Nine cities covering all regions of the State were studied, 500 households in each city. One resident in each household was randomly selected for testing. In survey rounds 1-8 we used the rapid WONDFO SARS-CoV-2 Antibody Test (Wondfo Biotech Co., Guangzhou, China). In rounds 9-10, we used a direct ELISA test that identifies IgG to the viral S protein (S-UFRJ). In terms of social distancing, individuals were asked three questions, from which we generated an exposure score using principal components analysis.
Antibody prevalence in early April 2020 was 0.07%, increasing to 10.0% in February 2021, and to 18.2% in April 2021. In round 10, self-reported whites showed the lowest seroprevalence (17.3%), while indigenous individuals presented the highest (44.4%). Seropositivity increased by 40% when comparing the most with the least exposed.
The proportion of the population already infected by SARS-Cov-2 in the state is still far from any perspective of herd immunity and the infection affects population groups in very different levels.
通过 2020 年 4 月至 2021 年 4 月连续进行的 10 项调查，描述巴西南里奥格兰德州的血清阳性率演变情况。
研究涵盖了该州所有地区的 9 个城市，每个城市有 500 户家庭。每个家庭随机选择 1 名居民进行检测。在第 1 至 8 轮调查中，我们使用了快速 WONDFO SARS-CoV-2 抗体检测试剂盒（中国广州万孚生物技术股份有限公司）。在第 9 至 10 轮调查中，我们使用了一种直接 ELISA 检测试剂盒，该试剂盒可识别针对病毒 S 蛋白的 IgG（UFRJ 大学）。关于社交距离，我们询问了个人三个问题，根据这些问题，我们使用主成分分析生成了一个暴露评分。
2020 年 4 月初的抗体流行率为 0.07%，到 2021 年 2 月增加到 10.0%，到 2021 年 4 月增加到 18.2%。在第 10 轮调查中，自报为白人的人群显示出最低的血清阳性率（17.3%），而原住民的阳性率最高（44.4%）。与暴露最少的人群相比，暴露最多的人群的血清阳性率增加了 40%。
该州人口中已经感染 SARS-CoV-2 的比例仍然远远达不到群体免疫的任何预期，而且感染的人群分布非常不均衡。
