WHO estimates global mortality rate for coronavirus is 3.4%

94,251 Cases reported worldwide Updated: March 4, 2020 94,251 Cases reported worldwide Updated: March 4, 2020 Photo: Johns Hopkins Mapping 2019-nCoV Photo: Johns Hopkins Mapping 2019-nCoV Image 1 of / 89 Caption Close WHO estimates global mortality rate for coronavirus is 3.4% 1 / 89 Back to Gallery

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As COVID-19 continues its march around the globe, scientists are trying to pin down the death rate, which will likely evolve in coming weeks and months.

The World Health Organization announced Tuesday that based on the current numbers, the global mortality rate for the disease caused by a new coronavirus was 3.4%. It is more fatal than the common flu which kills less 1% of those infected.

Death rates in outbreaks are likely to skew higher early on as health officials focus on finding severe and fatal cases, missing most milder cases. WHO says the majority of people with the new coronavirus experience only mild symptoms and do not require any treatment.

That said, the figure was a bit of a surprise, since a study from the Chinese Center for Disease Control looking at 44,000 patients who tested positive estimated the death rate was 2.3%.

"While many people globally have built up immunity to seasonal flu strains, COVID-19 is a new virus to which no one has immunity; that means more people are susceptible to infection, and some will suffer severe disease," Tedros Adhanom Ghebreyesus, the head of the World Health Organization said.

Ghebreyesus added that while COVID-19 isn't transmitted as easily as the flu, it "causes more severe disease."

When the outbreak was concentrated in Wuhan, China, the origin of the disease, the WHO estimated the death rate inside Wuhan was somewhere between 2% and 4% and outside the city it was 0.7%.

Dr. Lee Riley, a UC Berkeley professor and chair of the Division of Infectious Disease and Vaccinology, said mortality rate is frequently higher at the beginning of outbreaks because "we don't know how to deal with them."

"We have vaccines for influenza so this contributes to its lower rate, but if we didn't have the vaccines, the mortality rates for influenza would be higher than 0.1%," said Riley. "Also, mortality rates for influenza varies according to the virus strain causing the epidemic, which changes every year. So, it's too simplistic to compare mortality rates of two very different types of virus infections."

Dr. John Swartzberg, a professor of infectious disease at UC Berkeley, said the rate will likely drop. "I think the mortality rate will be much less when our testing becomes more robust," Swartzberg said. "Right now the bulk of the people being tested are those with symptoms or those with a known contact.

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The new estimate is based on all cases tracked around the world with the largest numbers in China and growing numbers in Italy, South Korea and Iran. There are now more than 93,000 cases around the world and over 3,100 deaths.

South Korea, Italy and Iran now account for 80% of the new virus cases outside China, according to the World Health Organization.

South Korea reported 435 new infections Wednesday, far smaller than its high of 851 a day earlier. A total of 5,621 people in South Korea have contracted the virus and 32 have died.

Iran reported 92 deaths among its 2,922 confirmed cases, the most of any country outside of China. Among the ill are members of the government, and the country canceled Friday prayers for the second week in a row.

Deaths in Italy rose to 79. The outbreak in Italy has been concentrated in the northern region of Lombardy, but fears over how the virus is spreading inside and outside the country has prompted the government to consider whether to close all schools nationwide for two weeks, rather than just ones in the cluster regions. Education Minister Lucia Azzolina told reporters that a final decision hadn’t been made yet.

In the U.S., more than 120 cases have been reported. Nine people have died, all in and around Seattle.

The Associated Press contributed to this story.

Amy Graff is a digital editor with SFGATE. Email her: agraff@sfgate.com.

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