In a study describing 138 patients with COVID-19 pneumonia in Wuhan, the most common clinical features at the onset of illness were:
Fever in 99 percent
Fatigue in 70 percent
Dry cough in 59 percent
Anorexia in 40 percent
Myalgias in 35 percent
Dyspnea in 31 percent
Sputum production in 27 percent
Other cohort studies of patients from Wuhan with confirmed COVID-19 have reported a similar range of clinical findings. However, fever might not be a universal finding. In one study, fever was reported in almost all patients, but approximately 20 percent had a very low grade fever <100.4°F/38°C . In another study of 1099 patients from Wuhan and other areas in China, fever (defined as an axillary temperature over 99.5°F/37.5°C) was present in only 44 percent on admission but was ultimately noted in 89 percent during the hospitalization.
Other, less common symptoms have included headache, sore throat, and runny nose. In addition to respiratory symptoms, gastrointestinal symptoms (eg, nausea and diarrhea) have also been reported in some patients, but these are relatively uncommon.
COVID-19 Incubation Period
Last updated: March 12, 15:00 GMT
2 - 14 days
Possible outliers: 0 - 27 days
Summary of findings:
2-14 days represents the current official estimated range for the novel coronavirus COVID-19.
However, a case with an incubation period of 27 days has been reported by Hubei Province local government on Feb. 22.
In addition, a case with an incubation period of 19 days was observed in a JAMA study of 5 cases published on Feb. 21.
Period can vary greatly among patients.
Mean incubation period observed:
3.0 days (0 - 24 days range, study based on 1,324 cases)
5.2 days (4.1 - 7.0 days range, based on 425 cases)
Mean incubation period observed in travelers from Wuhan:
6.4 days (range from 2.1 to 11.1 days)
COVID-19 Incubation Period
The incubation period (time from exposure to the development of symptoms) of the virus is estimated to be between 2 and 14 days based on the following sources:11.1
The World Health Organization (WHO) reported an incubation period for COVID-19 between 2 and 10 days.
China’s National Health Commission (NHC) had initially estimated an incubation period from 10 to 14 days.
The United States' Center for Disease Control (CDC) estimates the incubation period for COVID-19 to be between 2 and 14 days.
DXY.cn, a leading Chinese online community for physicians and health care professionals, is reporting an incubation period of 3 to 7 days, up to 14 days.
The estimated range will be most likely narrowed down as more data becomes available.
Incubation period of 5.2 days on average
A Chinese study published in the New England Journal of Medicine on Jan. 30, has found the incubation period to be 5.2 days on average, but it varies greatly among patients. The Chinese team conducting the study said their findings support a 14-day medical observation period for people exposed to the pathogen.
In its early stages, the epidemic doubled in size every 7.4 days. With a mean serial interval of 7.5 days (95% CI, 5.3 to 19), the basic reproductive number was estimated to be 2.2 (95% CI, 1.4 to 3.9).
NEW CASES IN THE LAST THREE WEEKS
Incubation Period (typical cases)
2-14 or 0-24 days
2-7 days, as long as 10 days
5 days (range: 2-14)
1-4 days, as long as 7 days
2 days (1-4 range)
On the basis of this information, there is evidence that human-to-human transmission has occurred among close contacts since the middle of December 2019.
Importance of knowing the incubation period
Understanding the incubation period is very important for health authorities as it allows them to introduce more effective quarantine systems for people suspected of carrying the virus, as a way of controlling and hopefully preventing the spread of the virus.
Comparison with other viruses
For comparison, the incubation period for the common flu (seasonal influenza) is typically around 2 days. Incubation period for other coronaviruses: SARS 2-7 days; MERS 5 days typically (range 2-14 days).