The highest risk factors for severe cases of the new coronavirus, COVID-19, are well-known at this point — those who are over 65, are immunocompromised or have preexisting conditions are more likely to develop severe cases of the virus. But data coming in from around the world on the death rates between men and women indicate that being male may be another risk factor.
Data out of China, Italy, France and South Korea all showed that men were dying of COVID-19 at higher rates than women. In Italy, an analysis from the Higher Health Institute of Rome of 25,058 cases found that 8 percent of male patients died, compared to 5 percent of female patients, The New York Times reported.
And in South Korea, which tested the majority of the country for the virus, 61 percent of confirmed cases were in women. But of the small number of citizens who died from COVID-19, 54 percent were men.
The skewed death rates between men and women appear to be occurring in the U.S. as well. While the Centers for Disease Control is not publicly sharing information on the sex of people who have died, The Washington Post analyzed the split between deaths in several states.
In Michigan, they reported, 61 percent of the 479 deaths in the state have been men. Florida was also at 61 percent for the 163 deaths, and the majority of cases — 53 percent — are male. In Washington state, 57 percent of the 284 deaths are in men.
In New York City, the hardest-hit area in the U.S., men are dying of COVID-19 at almost twice the rate of women, the Times said. For every 100,000 men in the city, 43 have died, while for every 100,000 women, 23 have died.
Experts aren’t exactly sure about why men are affected at a higher rate than women, but one reason could be a difference in their immune systems.
“We do know that men and women have biological differences in their immune responses and women’s immune responses in general tend to be stronger,” Dr. Emily Gurley, an infectious disease epidemiologist at the Johns Hopkins Bloomberg School of Public Health, tells PEOPLE.
The better immune response in women is true for a number of viruses, including HIV, hepatitis B and C, and “we’ve known about that for a long time,” says Gurley, “but we don’t know exactly how it’s playing out in COVID-19.
“It could be just down to natural differences in an immune response between men and women, but we don’t really know for sure,” she says.
Men are also more likely to have other diseases that put them at a higher risk of dying, such as heart disease, cancer and diabetes. Those underlying conditions make them more susceptible to developing severe cases of COVID-19, and dying.