Rare coronavirus cases can have long incubation period, warns leading Chinese respiratory expert
- Minority of Covid-19 cases took between 14 and 24 days before a positive diagnosis could be given, potentially complicating fight against disease
- Leading specialist Zong Nanshan says this only covers a minority of cases and the median period is three to seven days
The coronavirus that causes the Covid-19 illness had an unusually long incubation period in a minority of cases, one of China’s top respiratory specialists said on Tuesday.
The unusual length has raised concerns about giving an accurate diagnosis, but Zhong Nanshan said these cases were an exception.
He told a news briefing in Guangzhou that research suggested the incubation period could be as long as 24 days, but the median figure was three to seven days.
“It is a matter of considering the majority or the minority of cases. [Three to seven days] was the median figure and it applied for most cases,” Zhong said. “But I am not surprised that there are exceptions.”
Zhong and his team looked at data from 1,099 patients in 522 hospitals across the country. They had discovered only one patient with a 24-day incubation period and 13 cases with an incubation period of more than 14 days.
The 14-day mark is the World Health Organisation’s advisory period for monitoring cases and is based on data from other coronavirus diseases.