基于密切接触者人数推断新冠肺炎疫情发展趋势

密切接触者人数由于数据基数大且受统计口径变化影响较小,更能客观地反映新冠肺炎疫情的发展趋势。该文分析发现,2020年1月底-2月中旬北京市密切接触者转诊人数在新增确诊中的占比由50%提高接近100%,证实了严密筛查密切接触者并采取隔离措施对阻断新的传播风险的有效性。进一步对全国数据进行分析发现,全国累计密切接触人数逐步稳定在感染者数量的8倍左右,而新增密切接触者的增长率与5～6天后的新增确诊病例的增长率变化趋势一致。因此,追踪新增密切接触者的变化趋势,能提前一周左右推断新增确诊病例的变化,有利于各地医疗卫生机构做好应急准备工作,提前调度并储备相应救治物资,有效提升疫情防控效率。

Inferring the Trend of COVID-19 Epidemic with Close Contacts Counting

Close contacts with high-risk exposure to COVID-19 cases are more robust in statistics for inferring future development of COVID-19 epidemic. In Beijing, the proportion of close contact cases in newly confirmed cases had increased from about 50% at the end of January to nearly 100% in mid-February, indicating that contact tracing and quarantine measures are effective non-pharmaceutical interventions for containing the epidemic. In addition, we show at the national level that the cumulative number of close contacts was stabilized at about eight times as much as infected individuals, and the growth rate of daily close contacts was consistent with that of daily confirmed cases 5～6 days later. Consequently, tracking the daily change of close contacts is beneficial to predict the trend of the epidemic, based on which advanced medical supplies scheduling and effective epidemic prevention can be achieved.