Study confirms average incubation period of five days for COVID-19 outbreaks caused by new coronavirus

A new study from Johns Hopkins University’s Bloomberg School of Public Health confirms early estimates of the new coronavirus SARS-CoV-2, which has an average incubation period of 5.1 days for COVID-19 caused by infection. Understanding the incubation period of disease is key to controlling transmission. It refers in specifically the interval between initial exposure to pathogens and the ongoing symptoms of the host, and there are significant differences between diseases.

Study confirms average incubation period of five days for COVID-19 outbreaks caused by new coronavirus

Scanning electron microscope image (from: NIAID-RML)

In contrast, the incubation period for influenza is 1 to 3 days, while measles is 9 to 12 days. The new study examined 181 confirmed cases of COVID-19 and concluded that 97.5% of new coronavirus infections developed symptoms within 11.5 days.

It is important to note that this does not mean that all patients can return to normal immediately after five days, but rather strengthens the current two-week optimal isolation observation period for suspected cases.

Study confirms average incubation period of five days for COVID-19 outbreaks caused by new coronavirus

Exposure (blue) / seizure (red) / detection (green) time in 181 confirmed patients

“Based on our analysis of public data, the current recommendation for 14 days of active monitoring or isolation is reasonable, although some cases will be missed in the long run,” explains senior study author Justin Lessler.

As Lessler points out, the new study confirms that only a very small number of cases have an incubation period of more than 14 days. Estimates indicate that 101 of the 10,000 subjects may develop symptoms after 14 days.

Study confirms average incubation period of five days for COVID-19 outbreaks caused by new coronavirus

COVID-19 Profiling of confirmed patients (n-181)

But the researchers also weighed the social and economic costs of quarantine, suggesting that local authorities weigh the pros and cons by referring to the possible consequences of suspected cases.

For example, in some high-risk areas, active isolation monitoring for more than 14 days is recommended, such as cases where medical care has been exposed without wearing protective equipment.

Study confirms average incubation period of five days for COVID-19 outbreaks caused by new coronavirus

Cumulative distribution function of COVID-19 incubation period estimated from the positive normal model

Jonathan Ball, professor of molecular virology at the University of Nottingham, points out that it is clearly a tricky challenge to trace the source of an infectious disease accurately. We can only take a more conservative approach.

Details of the study have been published in the Annals of Internal Medicine, a recent issue.

Originally published as The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Cases: Marm and A the public.