On February 12, 2020, the World Health Organization rejected a suggestion from Chinese researchers to extend the recommended quarantine period for the novel coronavirus beyond 14 days, after a study posted online proposed an incubation period of up to 24 days. The WHO stated that the current 14-day quarantine remains appropriate, citing concerns that longer incubation claims may stem from double exposures rather than a single infection.
WHO stands by 14-day quarantine
The World Health Organization confirmed it will not change its guidance on the 14-day quarantine period for the novel coronavirus, despite a Chinese study suggesting the virus could incubate for up to 24 days. Dr. Michael Ryan, executive director of WHO’s Health Emergencies Programme, addressed the issue during a press briefing. He noted that long incubation periods observed in other diseases, such as Ebola, often result from multiple exposures rather than a single infection.
“What we have seen with Ebola is that sometimes a long incubation period can be due to a double exposure,” Ryan said. He added that the outlier data point of 24 days requires further review and more evidence before any policy changes could be considered.
Chinese study raises questions
The study in question, titled “Clinical characteristics of 2019 novel coronavirus infection in China,” was led by prominent Chinese epidemiologist and pulmonologist Zhong Nanshan. It was posted on medRxiv, an online archive for unpublished research manuscripts. The platform explicitly states that articles there are preprints and have not been peer-reviewed, meaning they should not be used to guide clinical practice.
The study analyzed data from 1,099 patients across China and found that the median incubation period was three days, with a range of zero to 24 days. The 24-day figure attracted significant attention, but health experts quickly cautioned against overinterpreting a single data point.
Experts warn of misinterpretation
Dr. Roger Seheult, a medical lecturer and creator of the MedCram YouTube channel, offered a detailed explanation of why the 24-day figure might be misleading. He suggested that what appears to be a long incubation period could actually be the result of a second infection occurring after an initial, asymptomatic one.
“There’s an infection that occurs in day 0 and there’s an incubation period of 10 days and then there’s another repeated one,” Seheult said. “This one may not cause symptom but this repeated one may cause symptom and that will be another incubation period.”
He stressed that the Chinese concept was interesting but likely based on a misperception. “What they don’t realize though is that there is another infection that occurred and that the total when added up, yes it comes out to 24 days. But that’s not the incubation period of this infection to this symptom.”
Peer review remains essential
The WHO’s rejection show the importance of peer review in medical research. The Chinese study, while drawing on a large dataset, has not undergone the rigorous evaluation that scientific journals require before publication. The medRxiv platform itself warns readers that preprint articles “report new medical research that has yet to be evaluated” and “should not be used to guide clinical practice.”
International scientists have been working around the clock to find effective treatments for the virus, which by February 12 had killed more than 1,000 people in China and infected around 40,000 globally. The WHO continues to coordinate global response efforts, including research into therapeutics and vaccines.
Public health authorities have reiterated that the 14-day quarantine period is based on the best available evidence and should be followed by anyone who may have been exposed to the virus. The WHO advises that individuals who develop symptoms such as fever, cough, or difficulty breathing should seek medical attention immediately.
The decision to maintain the 14-day quarantine reflects a cautious approach to a rapidly evolving outbreak. While Chinese researchers have contributed valuable data, the WHO’s stance highlights the need for verified, peer-reviewed science in guiding public health policy. As the outbreak continues to spread, the global medical community remains focused on containing the virus and reducing its impact on human health.
