https://www.cebm.net/covid-19/covid-19-what-proportion-are-a...
"Setting: Diamond Princess cruise ship, Yokohama, Japan (n=-634 tested positive).
Proportion: 18%"
Also:
"23 Residents of a Long-Term Care Nursing Facility King County, Washington
10 (43%) had symptoms, and 13 (57%) were asymptomatic."
But then:
"Seven days after testing, 10 of 13 asymptomatics developed symptoms"
That means that just 3 of 23 remained asymptomatic there too, i.e. 13%.
It is estimated that the people mostly spread this virus exactly in the phase where they still haven't developed symptoms, and the virus can be detected. But that doesn't mean they will remain without the symptoms.
Especially as we know the disease affects these demographics up to 100X more than the young.
For instance consider: "Emerging evidence suggests many more people are infected than tested. In Vo Italy, at the time the first symptomatic case was diagnosed, about 3%, had already been infected – most were completely asymptomatic." [1]
[1] https://www.cebm.net/covid-19/global-covid-19-case-fatality-...
Not a covid-19 symptom.
EDIT: I'm wrong, sorry. Thank you to kgwgk for the correction.
The most common symptoms of COVID-19 are fever, tiredness, and dry cough. Some patients may have aches and pains, NASAL CONGESTION, runny nose, sore throat or diarrhea.