Coronavirus Death Rate Is Far Lower Than the 2% Figure Being Thrown Around
Many of the cases go unrecorded because they do not even make the patient particularly sick
Health officials in China, racing to try to contain a fast-growing coronavirus outbreak, are principally recording severe cases of disease, using a case definition that cannot capture patients with mild illness, according to experts familiar with the surveillance efforts.
The approach, the experts told STAT, is likely resulting in both an underestimate in the total number of cases and flawed assumptions about fatality rates calculated by those who ignore the repeated caution that it’s too soon to do that math.
The experts were quick to note that the Chinese are not willfully underreporting cases. Rather, the approach is a testament to how challenging data collection can be during the early days of an epidemic. When thousands of sick people show up at hospitals looking for care, there is no time to go searching for people who have mild symptoms and who have stayed home.
“I think right now things are so chaotic in China it may be hard to collect data on the whole spectrum of illness,” said Michael Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota.
Officially, an estimated 20% of cases in China are severely ill, according to the World Health Organization. But that calculation is derived based on known cases, and would not reflect mild, undetected ones.
Without knowing for sure what percentage of cases is severe — and how easily the pathogen that causes the disease can be transmitted — it’s impossible to forecast what might happen if the virus continues to spread globally, the WHO’s emergencies chief, Mike Ryan, told reporters Wednesday.
“We don’t understand either of those parameters well enough to make accurate predictions,” he said. Still, he added a warning for people who are concluding that the virus may be less fatal than some other known pathogens: “A relatively mild virus can cause a lot of damage if a lot of people get it.”
The outbreak has infected upward of 7,700 people on the Chinese mainland, and killed 170 since the new virus [by now 259 deaths and 12,000 confirmed cases], known provisionally as 2019-nCoV, was reported to the WHO on Dec. 31. Nearly 20 other countries have reported diagnosing infections in travelers from the Chinese city of Wuhan, the epicenter of the outbreak, but to date there has been little local spread of the virus in other countries.
WHO Director-General Tedros Adhanom Ghebreyesus and Ryan, who were in China earlier this week to consult with the Chinese government and assess the situation, praised the response by officials there. “The challenge is great but the response has been massive,” Ryan told reporters.
The effort, which is of an unprecedented scale, involves quarantining whole cities that are home to tens of millions of people to try to stop spread of the virus. The WHO is still hopeful, Ryan said, that China will be able to stop the outbreak.