Coronavirus Mortality Rate: How COVID-19 Fatalities Compare to Ebola, SARS and MERS

As the outbreak of the new coronavirus continues to grow, experts around the world are working tirelessly to understand the characteristics of the mysterious new disease named COVID-19. That includes calculating its death rate, and seeing how it compares to that of other deadly diseases like Ebola, SARS and MERS.

What is known among experts as the case fatality rate—but commonly referred to as the mortality or fatality rate—is calculated by dividing the number of deaths by the total number of people infected. For instance, if 100 people die out of 1,000 people infected by any given disease, the mortality rate would be 10 percent.

As such, the mortality rate of a disease is changeable, and depends on a range of factors including the location of an outbreak, the health status of the infected person, and how much data has been accurately collected on the cases and deaths caused by the disease.

For the new coronavirus, which causes a disease called COVID-19, the average mortality rate is estimated to be in the range of 1 to 3 percent, Mike Tildesley, associate professor in the department of Life Sciences at the University of Warwick told Newsweek.

A summary of a report on over 72,000 COVID-19 cases by the Chinese Center for Disease Control and Prevention in the journal JAMA on Monday showed the case fatality rate was 2.3 percent on average, spiking to 14.8 percent in those aged 80 and above.

On Wednesday, NBC News reported the mortality rate in Iran—which has seen a spike in cases since it reported its first case last week—was around 14 percent. At the same time, as only 60 COVID-19 cases have been reported in the U.S. and no one has died, it isn't currently appropriate to estimate a mortality rate for that country, Tildesley explained.

Differences in reporting and healthcare systems in individual countries and their ability to manage outbreaks also affect the figure, Tildesley said. For example, officials in China changed how they count cases at least twice.

What's more, we still don't know how many people are infected but haven't shown symptoms and are therefore missing from the available data on cases, Tildesley said. "If this figure is high, then the true mortality rate will be significantly lower than the current estimates."

At present, COVID-19's fatality rate is relatively low compared to other deadly virus outbreaks in recent memory. Ebola, which in 2014 killed over 11,000 people in West Africa, has had a fatality rate between 25 percent to 90 percent depending on the outbreak.

SARS and MERS—fellow members of the large coronavirus family of viruses which now includes COVID-19—have mortality rates of around 10 percent and 35 percent, respectively, Tildesley said. Since it emerged in 2012, MERS has killed 858 people, while 774 people died of SARS during the 2003 outbreak.

As reflected in the map by Statista below, fresh cases of COVID-19 have popped up in new countries almost daily in the past couple of days, with concerning clusters appearing in Italy, South Korea, and Iran. On Wednesday, the U.S. Centers for Disease Control reported what is suspected to be the first example of what is known as "community spread." So, with all this going on, should the general public worry about figures like mortality rates or instead simply focus on preventing the spread of infection?

"It is completely understandable to be worried about mortality rates and evidence suggests that those most at risk are the elderly and those with underlying health conditions," said Tildesley.

"The best course of action is for us to try to minimise further spread of disease. It is important for us to follow good hygiene practices such as regular handwashing, covering coughs and sneezes with tissues, avoiding contact with people who are sick and in those cases, avoiding contact with the eyes, nose and mouth," he said.

Addressing fears that the virus could soon be declared a pandemic (where a pathogen has spread widely within two or more countries other than the first one to report it) Tildesley said: "The virus is concerning as we are now seeing spread in several countries in the world, so it is important to remain vigilant and to maintain the intervention protocols that are currently being put in place.

However, he cautioned: "The use of the term 'pandemic' can sometimes be distracting to the general public as it may give the impression that we are dealing with a virus that is 'uncontrollable' and spreading throughout the world.

"What should be stated is that health services around the world should be prepared for the possibility that COVID-19 cases may start to spread in their country and to ensure that contingency plans are in place to reduce the risk of large scale transmission," Tildesley argued.

Correction: This article originally stated 8,098 people died of SARS during 2003. This was the number of people who became sick. 774 people died.

The article originally stated the case-fatality rate of COVID-19 patients aged 70-79 years is 80 percent. It is 8 percent. Newsweek regrets these errors.