A recovered patient (R) waves to medical staff of the temporary hospital in Wuhan, central China's Hubei Province, Feb. 26, 2020.(Xinhua/Shen Bohan)

A research team led by Chinese top respiratory specialist Zhong Nanshan found that the median incubation period of the coronavirus disease was four days and nearly half of the patients did not have a fever when first admitted to the hospital. 

The team delineated the clinical characteristics of COVID-19 disease in China based on a dataset of 1,099 patients from 552 hospitals across the country during the first two months of the outbreak, in a research article published in The New England Journal of Medicine, a prestigious medical journal. 

The research found that the median incubation period of the disease was four days, with an interquartile range from two to seven days. 

Researchers recalculated the data after stripping out the extreme cases. Two patients from the sample were found with an incubation period of as long as 24 days, and for those living in Wuhan, Hubei Province for a long time or in contact with Wuhan residents, the incubation period was usually zero days. 

It would be misleading to assess the incubation period of a population solely on the basis of the minimum and maximum, the team noted. 

As for the clinical symptoms of the COVID-19 infection, fever and cough were the dominant symptoms and diarrhea was uncommon, which is similar to the SARS outbreak in China in 2003, said the article. 

Even though fever has been considered as an important indicator for diagnosis, the research showed that nearly half of the patients did not have a fever at the time of admission while 88.7 percent of them developed the symptom during hospitalization. 

The conventional routes of transmission of COVID-19 are mostly respiratory droplets and direct contact, however, the research pointed out that coronavirus has been detected in the gastrointestinal tract and urine as well, which indicated that more studies need to be done on these potential routes of transmission, 

The article also found that the fatality rate of the disease was 1.4 percent, which is more in line with the official data reported by the National Health Commission — a death rate of 3.2 percent among 51,857 cases of COVID-19 as of February 16. 

In the next study, the team will focus on the dynamics of viral transmission, the route of transmission and the virus' affinity for human tissue. 

Global Times 


Newspaper headline: Median incubation time 4 days: study