Department of Computer Science and Engineering, University of Bologna, Bologna, Italy
Department of Computer Science and Engineering, University of Bologna, Bologna, Italy.
BMJ Open. 2021 Jul 1;11(7):e051458. doi: 10.1136/bmjopen-2021-051458.
COVID-19's second wave started a debate on the potential role of schools as a primary factor in the contagion resurgence. Two opposite positions appeared: those convinced that schools played a major role in spreading SARS-CoV-2 infections and those who were not. We studied the growth rate of the total number of SARS-CoV-2 infections in all the Italian regions, before and after the school reopening (September-October 2020), investigating the hypothesis of an association between schools and the resurgence of the virus.
Using a Bayesian piecewise linear regression to scrutinise the number of daily SARS-CoV-2 infections in each region, we looked for an estimate of a changepoint in the growth rate of those confirmed cases. We compared the changepoints with the school opening dates, for each Italian region. The regression allows to discuss the change in steepness of the infection curve, before and after the changepoint.
In 15 out of 21 Italian regions (71%), an estimated change in the rate of growth of the total number of daily SARS-CoV-2 infection cases occurred after an average of 16.66 days (95% CI 14.47 to 18.73) since the school reopening. The number of days required for the SARS-CoV-2 daily cases to double went from an average of 47.50 days (95% CI 37.18 to 57.61) before the changepoint to an average of 7.72 days (95% CI 7.00 to 8.48) after it.
Studying the rate of growth of daily SARS-CoV-2 cases in all the regions provides some evidence in favour of a link between school reopening and the resurgence of the virus. The number of factors that could have played a role is too many to give a definitive answer. Still, the temporal correspondence warrants further systematic experiments to investigate on potential confounders that could clarify how much reopening schools mattered.
COVID-19 的第二波疫情引发了一场关于学校是否可能成为疫情反弹主要因素的辩论。出现了两种截然相反的观点：一种观点认为学校在 SARS-CoV-2 感染传播中起主要作用，另一种观点则认为学校的作用不大。我们研究了意大利所有地区 SARS-CoV-2 感染总数的增长率，在学校重新开放（2020 年 9 月至 10 月）前后，以调查学校与病毒再次出现之间是否存在关联的假设。
使用贝叶斯分段线性回归来仔细研究每个地区每天 SARS-CoV-2 感染的数量，我们寻找增长率的变化点，以确定确诊病例的估计值。我们比较了每个意大利地区的变化点与学校开放日期。回归分析可以讨论变化点前后感染曲线陡峭度的变化。
在 21 个意大利地区中有 15 个（71%），在学校重新开放平均 16.66 天后（95%置信区间 14.47 至 18.73），估计每天 SARS-CoV-2 感染总数的增长率发生了变化。SARS-CoV-2 每日病例数翻倍所需的天数从变化点前的平均 47.50 天（95%置信区间 37.18 至 57.61）变为变化点后的平均 7.72 天（95%置信区间 7.00 至 8.48）。
研究所有地区 SARS-CoV-2 每日增长率的变化为学校重新开放与病毒再次出现之间的联系提供了一些证据。可能起作用的因素太多，无法得出明确的答案。尽管如此，时间上的对应关系仍需要进一步的系统实验来研究潜在的混杂因素，以澄清学校重新开放的重要程度。
