The effect of lockdown on the COVID-19 epidemic in Brazil: evidence from an interrupted time series design

In response to the COVID-19 pandemic, governments worldwide have implemented social distancing policies with different levels of both enforcement and compliance. We conducted an interrupted time series analysis to estimate the impact of lockdowns on reducing the number of cases and deaths due to COVID-19 in Brazil. Official daily data was collected for four city capitals before and after their respective policies interventions based on a 14 days observation window. We estimated a segmented linear regression to evaluate the effectiveness of lockdown measures on COVID-19 incidence and mortality. The initial number of new cases and new deaths had a positive trend prior to policy change. After lockdown, a statistically significant decrease in new confirmed cases was found in all state capitals. We also found evidence that lockdown measures were likely to reverse the trend of new daily deaths due to COVID-19. In São Luís, we observed a reduction of 37.85% while in Fortaleza the decrease was 33.4% on the average difference in daily deaths if the lockdown had not been implemented. Similarly, the intervention diminished mortality in Recife by 21.76% and Belém by 16.77%. Social distancing policies can be useful tools in flattening the epidemic curve.

为应对新型冠状病毒肺炎（COVID-19）疫情，全球各国政府均推行了社交防疫距离政策，且不同地区的政策执行力度与民众依从度存在差异。本研究针对巴西开展中断时间序列分析，以评估封控措施对降低新冠确诊病例与死亡人数的影响。研究基于14天的观测窗口，收集了巴西四座州府城市在各自封控政策实施前后的官方每日数据。本研究通过分段线性回归模型，评估封控措施对新冠发病率与死亡率的干预效果。政策实施前，新增确诊病例与新增死亡人数均呈正向增长趋势。封控实施后，所有州府城市的新增确诊病例数均出现统计学意义上的显著下降。研究同时证实，封控措施可有效扭转新冠每日新增死亡人数的增长趋势。若未实施封控，圣路易斯（São Luís）的每日新增死亡人数平均将减少37.85%，福塔莱萨（Fortaleza）则减少33.4%；同理，本次干预措施使累西腓（Recife）的死亡率降低21.76%，贝伦（Belém）降低16.77%。社交防疫距离政策可作为有效手段，助力平缓疫情传播曲线。