Scientists Want To Know Why More Men Than Women Are Apparently Dying Of COVID-19

Men appear to be more likely to die from COVID-19 than women. Scientists have theories — women may have better immune systems, or sex hormones may play a role in the body's response to infection.

MARY LOUISE KELLY, HOST:

Men seem to be hit harder by the coronavirus than women. Around the world, it appears more men than women are dying from the virus. Now, the reason for this is not exactly clear. There are some possible explanations, and NPR science correspondent Nell Greenfieldboyce is here to walk us through them.

Hey, Nell.

NELL GREENFIELDBOYCE, BYLINE: Hello.

KELLY: So what is the data? I mean, how sure are we that COVID-19 is - can be more severe in men than in women?

GREENFIELDBOYCE: People started noticing this almost as soon as the first clinical reports came out of Wuhan describing the cases in China. There was one large study that looked at nearly 40,000 cases, and it found that the fatality rate was higher for men. It was 2.8% for men compared with only 1.7% for women. And that's basically held true as the virus has moved to other countries. Like, in Italy, there was this one study of 1,500 cases of critically ill people with the virus who were admitted into the ICUs, the intensive care units. And about 80% of them were men.

KELLY: And how about here in the U.S.? What do we know?

GREENFIELDBOYCE: So it's hard to get a hold of some of these numbers. The Centers for Disease Control and Prevention hasn't been providing a kind of sex breakdown of their data. But there was one study just recently looking at over 1,400 people hospitalized with the virus in March, and about 54% were male - so men a little overrepresented there. Some states are giving out more detailed information. New York state - New York City, for example, has this information. And you can see more men are known to have the virus. More men have been hospitalized, and they seem to be dying at nearly twice the rate as women.

KELLY: So - all right. Let's get to the why. Start with biological differences. Might there be - might one factor be biological differences between males and females?

GREENFIELDBOYCE: Yeah. I mean, there are real differences between male and female immune responses. That's been seen in all kinds of studies. I mean, females are much more likely to get autoimmune diseases, for example. Females have two copies of the X chromosome, and it turns out there's a lot of immune-related genes on that chromosome. Women seem to generally mount a greater and more robust immune reaction to infections. We know this is true for viruses like HIV and hepatitis C.

So you know, we may learn more about this for this coronavirus. I talked with one researcher who'd actually just gotten some funding from the National Institutes of Health to start looking at sex differences between men and women's immune responses to the virus.

KELLY: What about another possible factor, which is men and women moving through the world differently - that maybe women are more likely to take care of themselves overall?

GREENFIELDBOYCE: Yeah, the sort of social factors. I mean, early on in China, it was suggested that maybe it was because men were far more likely to smoke cigarettes than women. There's also been the thinking that maybe men tend to engage in other kinds of risky behavior, like drinking more alcohol, that they might be less likely to look after their health in general. I mean, there's even been studies of hand-washing. It turns out men are less likely to wash their hands after, say, going to the bathroom.

KELLY: What are the implications of this, Nell, either for being able to treat people who've been confirmed with COVID-19 or vaccines trying to prevent them from getting it in the first place?

GREENFIELDBOYCE: Well, if there are real male-female differences, it would be good to know that when you start to go into vaccine development. When you want to look at the immune response, you want to make sure that you're looking at it for both men and women. And in terms of treatment, you know, it would be good for men to know that researchers are seeing this because being male seems to almost be a risk factor like being older. And so men and women need to think about that, and they need to take precautions, you know, with that in mind.

KELLY: Thank you, Nell.

GREENFIELDBOYCE: Thank you.

KELLY: NPR's Nell Greenfieldboyce reporting.

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