The average time of incubation of the coronavirus respiratory virus is 5.1 days, according to a study by scientists at Johns Hopkins University, in Maryland, United States, based on available public data.
This period, between exposure and the appearance of the first symptoms, suggests that the quarantine of fourteen days advised by disease prevention centers around the world to people with possible contagion is a reasonable period.
The analysis of public data on the infection of SARS-CoV-2, the cause of COVID-19, suggests that 97.5% of people with symptoms of infection do so within 11.5 days of exposure.
In addition, the researchers estimate that for every 10,000 people isolated for 14 days, only 101 could have symptoms after the quarantine is over.
“According to our analysis of the available data, the current recommendation of fourteen days of quarantine is reasonable, although in that period some cases could be ignored in the long term,” says study lead author Justin Lessler.
For the study, published Monday in the magazine Annals of Internal Medicine, the scientists studied 181 cases from China and other countries detected and reported in the media before February 24.
Most of the cases were people who traveled to or from Wuhan or were in Hubei, a province whose capital is Wuhan.
The worldwide outbreak of coronavirus arose in December 2019 in Wuhan and since then has caused 95,333 officially confirmed cases worldwide and 3,282 deaths from pneumonia due to the virus, according to the WHO March 5 report.
Most cases are from Wuhan and Hubei Province. However, dozens of countries have been equally affected, especially South Korea, Iran and Italy, but also others such as the United States and Spain.
An accurate estimate of the disease incubation period for a new virus such as this facilitates the work of epidemiologists and allows public health officials to devise an effective quarantine and other disease control measures.
Quarantines help to slow the spread of the virus and, in some cases, also stop the infection, even if there are atypical cases with incubation periods longer than quarantine days.
Lessler recognizes that isolating people and preventing them from going to work has a significant economic and social cost that is evident when quarantine affects health workers and emergency managers such as firefighters.
The incubation period of the new coronavirus is in the same range as the SARS that infected humans and caused a major outbreak in southern China and Hong Kong between 2002 and 2004.
Meanwhile, for the MERS, which generates hundreds of cases in the Middle East with a relatively high mortality rate, the average incubation period is 5 to 7 days.
Human coronaviruses that cause common colds have average disease incubation periods of about three days.