Nearly 76,000 people in the city of Wuhan, China, may have already been infected with the new coronavirus, an estimate that is far higher than the number of cases reported so far, researchers say.
On Friday, Chinese health officials said nearly 10,000 cases of the virus called 2019-nCoV have been reported, with 213 deaths at this point. The World Health Organization declared the outbreak an international public health emergency on Thursday.
Since the outbreak started in late December, Chinese health officials have determined that the virus, traced to a wild animal market in Wuhan, is now spreading from human to human and that transmission can occur before symptoms appear.
The new computer modeling study delivered more bad news: Estimates suggest that a number of major cities in China have each already had dozens of people infected with 2019-nCoV arrive from Wuhan, and in numbers large enough to trigger local epidemics.
That points up the need for a rapid and immediate increase of major public health control measures to prevent large epidemics in areas outside Wuhan, the researchers said.
The findings were published Jan. 31 in The Lancet medical journal.
“Not everyone who is infected with 2019-nCoV would require or seek medical attention. During the urgent demands of a rapidly expanding epidemic of a completely new virus, especially when system capacity is getting overwhelmed, some of those infected may be undercounted in the official register,” explained study senior author Gabriel Leung, a professor and public health expert at the University of Hong Kong.
“The apparent discrepancy between our modeled estimates of 2019-nCoV infections and the actual number of confirmed cases in Wuhan could also be due to several other factors,” Leung added in a journal news release. “These include that there is a time lag between infection and symptom onset, delays in infected persons coming to medical attention, and time taken to confirm cases by laboratory testing, which could all affect overall recording and reporting.”
The researchers also said their modeling suggests that if transmissibility of 2019-nCoV could be reduced, both the growth rate and size of local epidemics in all cities across China could be reduced.
“If the transmissibility of 2019-nCoV is similar nationally and over time, it is possible that epidemics could be already growing in multiple major Chinese cities, with a time lag of one to two weeks behind the Wuhan outbreak,” said study lead author Joseph Wu, a professor at the University of Hong Kong.
“Large cities overseas with close transport links to China could potentially also become outbreak epicenters because of substantial spread of pre-symptomatic cases unless substantial public health interventions at both the population and personal levels are implemented immediately,” Wu said in the release.
The U.S. Centers for Disease Control and Prevention has more on 2019-nCoV.