The potential spread of Covid-19 and government decision-making: a retrospective analysis in Florianópolis, Brazil

ABSTRACT: Objective: To analyze the association between the transmission potential of SARS-CoV-2 and the decisions made by the municipal government of Florianópolis (Brazil) regarding social distancing. Methods: We analyzed new cases of COVID-19 identified in Florianópolis residents between February 1 and July 14, 2020, using a nowcasting approach. Decrees related to COVID-19 published in the Official Gazette of the Municipality between February 1 and July 14, 2020 were also analyzed. Based on the actions proposed in the decrees, whether they loosened social distancing measures, or increased or maintained existing restrictions, was analyzed, thus creating a Social Distancing Index. Time-dependent reproduction numbers (Rt) for a period of 14 days prior to each decree were calculated. A matrix was constructed associating the classification of each decree and the Rt values, analyzing the consonance or dissonance between the potential dissemination of SARS-CoV-2 and the actions of the decrees. Results: A total of 5,374 cases of COVID-19 and 26 decrees were analyzed. Nine decrees increased social distancing measures, nine maintained them, and eight loosened them. Of the 26 actions, 9 were consonant and 17 dissonant with the tendency indicated by the Rt. Dissonance was observed in all of the decrees that maintained the distance measures or loosened them. The fastest expansion in the number of new cases and the greatest amount of dissonant decrees was found in the last two months analyzed. Conclusion: There was an important divergence between municipal measures of social distancing with epidemiological indicators at the time of each political decision.

摘要：
研究目的：分析严重急性呼吸综合征冠状病毒2型（SARS-CoV-2）的传播潜能与巴西弗洛里亚诺波利斯市政府制定的社交距离管控政策之间的关联。
研究方法：本研究采用即时预测（nowcasting）方法，对2020年2月1日至7月14日期间弗洛里亚诺波利斯居民确诊的新型冠状病毒肺炎（COVID-19）新增病例进行分析；同时梳理同期刊登于该市官方公报的所有与COVID-19相关的政令。根据政令提出的社交距离措施调整方向——即放宽、维持或加强现有限制，构建社交距离指数。计算每一项政令发布前14天的时间依赖性再生数（Rt）。构建关联矩阵，将各项政令的分类与Rt值进行匹配，分析SARS-CoV-2潜在传播风险与政令举措之间的契合度与偏离程度。
研究结果：本研究共分析5374例COVID-19病例与26项政令。其中9项政令加强了社交距离管控措施，9项维持现有管控力度，8项放宽了相关限制。26项政策举措中，9项与Rt指示的病毒传播趋势契合，17项与之存在偏离。所有维持或放宽社交距离措施的政令均出现了政策与疫情趋势的偏离。在本次分析的最后两个月中，新增病例数增长最快，且存在偏离的政令数量最多。
研究结论：在每一项政策决策出台时，该市的社交距离管控措施与当时的流行病学监测指标之间存在显著分歧。