The COVID-19 appears to be highly contagious and is primarily spread by droplets. Containment efforts have emphasised quarantine during the incubation period as the most effective measure to limit spread. Because of the personal and economic toll of this measure and its implication for transmission, there is a need to maximise our understanding of the incubation period.
Some scientists studied the case records of 181 patients (median age, 44.5 years; 60 per cent male) who had visited Wuhan, the epicenter of coronavirus in China where the infection was first identified (161 cases), or been in contact with an infected person before becoming symptomatic and testing positive for COVID-19 between January 4 and February 24, 2020.
The investigators classified risk for undetected symptomatic infection as low (1 in 10,000), medium (1 in 1000), or high (1 in 100) and considered monitoring programs of varying length.
In the resulting models, estimated median incubation time (IT) of COVID-19 was 5.1 days – mean incubation time was 5.5 days.
For 97.5 per cent of infected persons, symptoms appear by 11.5 days. Fewer than 2.5 per cent are symptomatic within 2.2 days. Estimated median IT to fever was 5.7 days.
Among 108 patients diagnosed outside mainland China, median IT was 5.5 days; the 73 patients diagnosed inside China had a median IT of 4.8 days. Using exposures designated as high risk and a 7-day monitoring period, the estimate for missed cases was 21.2 per 10,000.
After 14 days, the estimated number of missed high-risk cases was 1 per 10,000 patients.
Agencies
