Among the spread of the current coronavirus epidemic, it can be difficult to find science-based advice, since much of the information out there is only precautionary or absolutely wrong. Fortunately, we get more data on a daily basis.
Now, the latest research at Johns Hopkins University has shown that COVID-19 has an average incubation period of 5.1 days, which means that the 14-day quarantine period recommended by the CDC is very convenient.
Health officials need to make important decisions based on limited information, and it is always good that this decision is supported by science.
The Johns Hopkins team investigated 181 COVID-19 cases outside of Hubei province in China before February 24 this year.
By recording the time of possible exposure, onset of symptoms, onset of fever and detection by the authorities for each case, the team created a distribution model of the incubation period.
Put simply, the incubation period is the time between exposure to the disease and the onset of the onset of symptoms. This is usually before the infectious period, when you are likely to give the disease to others.
We don’t yet know how contagious coronavirus is when people show no symptoms, however, there have been some reports of people passing on the virus without showing any symptoms.
That said, as with other coronaviruses (such as the common cold), you are much more likely to pass on the virus to someone else while coughing or sneezing.
The Johns Hopkins team found that less than 2.5 percent of those infected would show symptoms within 2.2 days; the estimated median incubation period was 5.1 days; and 97.5 percent will show symptoms within 11.5 days.
“Based on our analysis of publicly available data, the current 14-day recommendation for active monitoring or quarantine is reasonable,” says epidemiologist Justin Lessler of the Johns Hopkins Bloomberg School of Public Health.
“Although some cases would be lacking in the long run at that time.”
This type of research is incredibly useful for infectious disease specialists who are making political decisions for coronavirus.
It was feared that the incubation period was not long enough, after other teams of researchers discovered incubation periods that lasted up to 19 and 24 days.
Extrapolating from 181 cases, the Johns Hopkins team estimated that for every 10,000 people quarantined for 14 days, approximately 101 would develop symptoms after release.
Further research – with larger groups of people – will need to be conducted to confirm whether longer incubation periods could cause problems for our current quarantine policies.
And for the rest of us, until a vaccine is created, the best way to fight the virus is to keep calm, wash your hands (for 20 seconds!) And if you feel bad – stay home.
The research was published in Annals of internal medicine.