Is a 14-day quarantine period optimal for effectively controlling coronavirus disease 2019 (COVID-19)?

Xue Jiang; Yawei Niu; Xiong Li; Lin Li; Wenxiang Cai; Yucan Chen; Bo Liao; Edwin Wang

The median incubation period for adults in this cohort was 7-day, which was longer than 5-5.2 days reported previously 3, 4 . Recently, the Chinese Medical Association also found that the coronavirus median incubation period was 5-7 days 5 . Kids had an incubation period of 9-day and significantly longer than adults. Based on previous studies, WHO has set a 14-day quarantine period for Covid-19. However, we found that that the incubation periods of 11.5% (n=233) of the cases were longer than 14 days, meaning that the current quarantine policy only stops 88% of the cases for virus spreading. This finding is similar to another report showing that 13 (12.7%) cases had their incubation time longer than 14 days 4 . In general, a quarantine period that retains about 95% of the cases developing symptoms will be more effective 6 . Thus, we further analyzed the subset (n=233) and found that 98.7% and 97.9%, respectively, of the men and women cases who are developing the disease, will be quarantined, if everybody or adults alone, respectively, take an extra 7-day of isolation (i.e., a quarantine period of 21 days). If taking a quarantine period of 17-day or 18-day, 94.8% and 96.2%, respectively, of the cases developing symptoms will be successfully quarantined.