Pedro C. Hallal, Mariângela F. Silveira, Ana M. B. Menezes, Bernardo L. Horta, Aluísio J. D. Barros, Nadege Jacques, Luís Paulo Vidaletti, Fernando P. Hartwig, Fernando C. Barros, and Cesar G. Victora are with the Postgraduate Program in Epidemiology, Universidade Federal de Pelotas, Brazil. Lúcia C. Pellanda and Helena Schirmer are with the Universidade Federal de Ciências de Saúde de Porto Alegre, Brazil. Gabriel D. Victora is with the Laboratory of Lymphocyte Dynamics, Rockefeller University, New York, NY. Odir A. Dellagostin is with the Postgraduate Program in Biotechnology, Universidade Federal de Pelotas. Claudio J. Struchiner is with the Fundação Getúlio Vargas, Rio de Janeiro, Brazil. Marcelo N. Burattini is with the Universidade Federal de São Paulo, Brazil. Marilia A. Mesenburg is with the Postgraduate Program in Epidemiology, Universidade Federal de Pelotas, and the Universidade Federal de Ciências de Saúde de Porto Alegre. Emanuele L. Ambros is with the Secretaria Municipal de Saúde de Uruguaiana, Brazil. Evelise M. Berlezi is with the Universidade de Ijuí, Brazil. Jane D. P. Renner is with the Universidade de Santa Cruz do Sul, Brazil. Kaue Collares is with the Universidade de Passo Fundo, Brazil. Maria Letícia R. Ikeda is with the Universidade do Vale do Rio dos Sinos, Sao Leopoldo, Brazil. Thiago M. Ardenghi is with the Universidade Federal de Santa Maria, Brazil. Patricia de Gasperi is with the Universidade de Caxias do Sul, Brazil.
Am J Public Health. 2021 Aug;111(8):1542-1550. doi: 10.2105/AJPH.2021.306351. Epub 2021 Jun 29.
To evaluate the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) over 6 months in the Brazilian State of Rio Grande do Sul (population 11.3 million), based on 8 serological surveys. In each survey, 4151 participants in round 1 and 4460 participants in round 2 were randomly sampled from all state regions. We assessed presence of antibodies against SARS-CoV-2 using a validated lateral flow point-of-care test; we adjusted figures for the time-dependent decay of antibodies. The SARS-CoV-2 antibody prevalence increased from 0.03% (95% confidence interval [CI] = 0.00%, 0.34%; 1 in every 3333 individuals) in mid-April to 1.89% (95% CI = 1.36%, 2.54%; 1 in every 53 individuals) in early September. Prevalence was similar across gender and skin color categories. Older adults were less likely to be infected than younger participants. The proportion of the population who reported leaving home daily increased from 21.4% (95% CI = 20.2%, 22.7%) to 33.2% (95% CI = 31.8%, 34.5%). SARS-CoV-2 infection increased slowly during the first 6 months in the state, differently from what was observed in other Brazilian regions. Future survey rounds will continue to document the spread of the pandemic.
为评估严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）在巴西南里奥格兰德州（人口 1130 万）6 个月内的传播情况，我们基于 8 项血清学调查进行研究。在每一次调查中，首轮从全州所有地区随机抽取 4151 名参与者，次轮抽取 4460 名参与者。我们使用经验证的侧向流动即时检验来评估针对 SARS-CoV-2 的抗体存在情况；我们对抗体的时间依赖性衰减进行了校正。SARS-CoV-2 抗体的流行率从 4 月中旬的 0.03%（95%置信区间[CI] = 0.00%，0.34%；每 3333 人中就有 1 人）上升至 9 月初的 1.89%（95% CI = 1.36%，2.54%；每 53 人中就有 1 人）。性别和肤色类别之间的流行率相似。年龄较大的成年人比年轻参与者感染的可能性更小。每天离家外出的人口比例从 21.4%（95% CI = 20.2%，22.7%）增加到 33.2%（95% CI = 31.8%，34.5%）。在该州，SARS-CoV-2 的感染在头 6 个月内缓慢增加，与巴西其他地区的情况不同。未来的调查轮次将继续记录大流行的传播情况。
