The incubation period of COVID-19 infection could be as long as eight days, according to a new study that involved assessing many patient samples.
Incubation period is the time from the start of infection to the onset of symptoms. Incubation period for coronavirus was previously thought to be around 4-5 days.
According to the scientists, including Chong You from Peking University in China, the previous estimate of smaller incubation period were based on small sample sized, limited data, and self-reports that could be biased by memory or judgement of the patient or interviewer.
The approach is better as it relies on public database of dates of infection, and uses statistical methods to reduce recall bias.The new approach helped to measure the average incubation period as 7.75 days, with only 10 percent of the patients showing an incubation period of 14.28 days.
The findings may not apply to later cases in other parts of the world where the virus may have mutated. It may also challenge health authorities who rely on the standard 14-day quarantine.
By providing health authorities with a potentially more accurate figure for the incubation period, the results could inform guidelines for containment efforts such as quarantines and studies investigating the disease's transmission.
"Countries and health authorities have implemented various containment measures such as quarantines to slow the spread of Covid-19," the Chinese researchers wrote.
"To work effectively, these strategies depend on understanding the disease's incubation period, or the time between someone becoming infected and showing the first symptoms of the disease, and how much it varies from individual to individual," they added.