The incubation period is not 25-30 days. The mean incubation period is 5-6 days, range 1-14 days.
Source: Page 12, paragraph 2. https://www.who.int/docs/default-source/coronaviruse/who-chi...
Source: Page 12, paragraph 2. https://www.who.int/docs/default-source/coronaviruse/who-chi...
> The median incubation period was 3.0 days (range, 0 to 24.0 days)
Edited my post to include that source
https://www.medrxiv.org/content/10.1101/2020.02.28.20028068v...
"The mean incubation was 8.42(95% confidence interval [CI], 6.55-10.29) days... COVID-19 course was approximately 2 weeks."
Fairly small sample size of 55 patients, which means the reliability may be debatable, and giving figures to two decimal places is meaningless. (In fact any decimal places are meaningless, unless someone times the exact moment of exposure.)
That aside - it seems very unlikely that 24 day incubations will be common.
Broadly it seems most people who become symptomatic will show symptoms within 10 days and will recover within two weeks after the symptoms appear. A small percentage - mostly older and unwell - will become seriously ill, and an even smaller percentage will die.
Meanwhile the presence of untraceable infections strongly suggests that a significant number of people - possibly a majority - either don't develop symptoms at all, or don't consider them serious enough to require medical attention.
I don't see that supported by the CDC either though
There are several cases where the incubation period has been over 20 days. Maybe 90% of cases incubate for 14 days or less. Maybe 99% for less than 20.
14 days is not some magic limit.
There are case reports of it being far longer than 14 days:
https://www.reuters.com/article/us-china-health-incubation/c...
> A 70-year-old man in China’s Hubei Province was infected with coronavirus but did not show symptoms until 27 days later, the local government said on Saturday, meaning the virus’ incubation period could be much longer than the presumed 14 days.
[1] Shennongjia, Hubei. Looks like it's a "county" with about 75k people: https://en.wikipedia.org/wiki/Shennongjia
[2] For instance: he visited Wuhan, self-quarantined immediately after returning which limited his contact with others, then 27 days later developed infection. Every contact he did have was tracked and confirmed negative. That's total speculation, though.