A new study suggests that the coronavirus death rate in Wuhan, China, may be 1.4%—several percentage points lower than previous estimates, providing at least one heartening data point for a world reeling from the spread of COVID-19.
The study, published Thursday in the medical journal Nature Medicine by researchers at the University of Hong Kong and Harvard University, found that 1.4% of people who tested positive and developed COVID-19 symptoms died. It focused on coronavirus patients in Wuhan, the central Chinese city where the coronavirus first appeared.
The study found that the fatality rate rose to 2.6% for people aged 60 and up and dropped to 0.3% for people under 30. (In the U.S., the average seasonal flu, by comparison, has a 0.1% fatality rate.) The study also found that the risk of symptomatic infection increased with age.
The study’s fatality rate is lower than previous estimates for Wuhan. In mid-February, a team of experts commissioned by the World Health Organization pegged the death rate in Wuhan at 5.8% during the early days of the outbreak.
The 1.4% rate is also lower than the WHO’s estimate for the coronavirus fatality rate globally, thought to be 3.4% as of early March.
The latest study offers a more complete picture of the coronavirus’s effect on Wuhan patients. It analyzed the number of cases and deaths as of Feb. 29; the earlier WHO report used data through Feb. 20, when there were thousands fewer cases and hundreds fewer deaths.
The new study also includes data from travelers who left Wuhan on commercial flights before Jan. 19 and via chartered flights from Jan. 29 to Feb. 4 and later tested positive for COVID-19. The researchers reasoned that those patients should be considered “Wuhan” cases, since they most likely became infected in the city.
Fatality rates are often higher at the start of an outbreak, when there is less data and when hospitals are overwhelmed, and mild or asymptomatic cases might slip past detection. (The WHO-commissioned report noted that the standard of health care in Wuhan had evolved over the course of the outbreak and said the fatality rate was decreasing over time.)
As of Friday, COVID-19 has sickened 245,000 globally and led to 10,000 deaths, according to data from Johns Hopkins University.
China still has the most reported COVID-19 cases, at 81,000, but according to official data, infections are slowing, and the health commission of Hubei Province, where Wuhan is located, said on Wednesday there were zero new confirmed cases in the province.
Of China’s 3,250 coronavirus-related deaths, 3,130 occurred in Hubei.
Demographics, health system capacity, and diagnostic capability all factor into how a country responds to an epidemic and how fatal it is in any given place.In South Korea, which has the highest testing rate in the world, around 1% of COVID-19 patients pass away; in Italy, the country with the second-oldest population on earth, the death rate is 8%. Italy has the second-highest number of reported cases at 41,000 but the world’s highest number of deaths—over 3,400 as of Friday.
The HKU medical faculty news release about the new study said the “seemingly low” 1.4% fatality rate still does not account for asymptomatic cases and urged the continued enforcement of social distancing.
The study estimated that one-quarter to one-half of the population will become infected “absent drastic control measures or a vaccine.”
The study continued, “Perhaps the most important target of mitigation measures would be to ‘flatten out’ the epidemic curve, reducing the peak demand on health care services and buying time for better treatment pathways to be developed.”
More coronavirus coverage from Fortune:
—This famed economist doesn’t think we’re headed for another Great Recession
—South Korea has the most comprehensive coronavirus data. What it’s taught us so far
—10 questions about the 2020 election during the coronavirus pandemic, answered
—6 steps to sustainably flatten the coronavirus curve
—How hackers are exploiting the coronavirus—and how to protect yourself
—Hong Kong launches surveillance operation to track suspected coronavirus patients
—Listen to Leadership Next, a Fortune podcast examining the evolving role of CEO
—WATCH: The race is on to create a coronavirus antiviral drug and vaccine
Subscribe to Fortune’s Outbreak newsletter for a daily roundup of stories on the coronavirus outbreak and its impact on global business.
