In March, 2 papers on the coronavirus and carried out in China were published (one in the New England Journal of Medicine), which provide important about what are the symptoms of coronavirus. The two studies included 1247 patients infected by Covid-19 and confirmed by laboratory tests.
Age of the affected population
The mean age of the patients in each study was 47 and 50 years, respectively, with the oldest being 88 years in one job and 71 years in another. Between both studies there were 12 patients younger than 15 years. In the New England Journal of Medicine study, the incubation period was defined as the interval between the date of contact with a possible infected person and the first day of the onset of symptoms. The average incubation period was 4-5 days, the longest being 7 days (this does not exclude that in a minority of patients it can be extended to 14 days). Forty-four % of patients in one study and 70% in another had fever upon admission to hospital. However, it is important to note that in 30-40% of these patients the fever ranged from 37.3 to 38ºC.
Expectoration and dry cough as usual symptoms
The two studies also report that around 33% of the patients had cough with expectoration (mucous secretions when coughing). Only 14% of the patients had a sore throat and over 15% muscle pain. The duration of hospitalization of the discharged patients was 12 days (6-21 days).
In summary, these articles provide important news regarding Covid-19 infection. First, the incubation period for the infection was 4-5 days, with a maximum of 7 days (14 days incubation period, although possible, should be rare). In any case, these data should be taken with cautious, since the exact date of infection is not known with complete accuracy in this infection, as it occurs in other diseases (transfusion and viral hepatitis).
On the other hand, 30-40% of the cases had fever below 38ºC, and some even 37.3ºC or less. Finally, it is important to note that although about 68% of the patients had cough, 33% of them presented a productive cough with expectoration.
We consider important to take this information into account so as not to exclude patients with fever below 38ºC and even without fever from the diagnosis of this disease, nor to limit the diagnostic suspicion to those cases who have a dry cough since a significant percentage of patients present cough and expectoration.
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