Hand washing habits or hormones? With nearly 50% more men than women dying from COVID-19, researchers are looking for answers

LONDON, March 4 (Thomson Reuters Foundation) - When Chinese authorities released data on coronavirus deaths, one striking trend emerged - fewer women were dying than men.

Researchers looked at 44,672 confirmed cases of coronavirus in China from late 2019, when the virus first emerged, to Feb. 11. Most experienced only mild symptoms but 1,023 died - an overall death rate of 2.3%. Of these, 653 were men. Despite the fact that roughly equal numbers of men and women in China caught COVID-19 - which is now confirmed to have killed more than 3,000 people globally - the death rate among male victims was significantly higher, at 2.8% compared to 1.7% for women. That represents a 48.89% difference.

Should we be surprised by this? It’s hard to say. While no two viruses are the same, looking at similar outbreaks can offer some insights. Other major coronavirus outbreaks - including Severe Acute Respiratory Syndrome (SARS), which originated in China in 2003, and Middle East Respiratory Syndrome (MERS), first reported in Saudi Arabia in 2012 - also killed more men than women. Research on mice also suggests males may be more vulnerable to these viruses.

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One theory behind this difference is hormones. Research by Stanley Perlman, a professor of microbiology and immunology at the University of Iowa, showed female mice were less susceptible to the SARS virus than males. But when the female hormone estrogen was blocked, or their ovaries were removed, the female mice were more likely to die.

"Our results would suggest it's probably something intrinsic, and it may be hormonal," said Perlman.

Although the sample is quite large, it is still hard to draw any firm conclusions. Scientists say a number of environmental factors could have played into the statistics, from differences in how male and female patients were treated to lifestyle factors. For example, Chinese men are more likely than women to be regular smokers.

Separately, studies have found that men — even health care workers — are less likely to wash their hands or to use soap than women, a practice that could limit the spread of the virus.

The implications are probably limited at this stage. Perlman said that all else being equal, if two people came down with the disease he "might be a little more worried about the male".

The World Health Organization (WHO) does not distinguish between the sexes in advice on its website, which says only that "older people, and those with pre-existing medical conditions (such as high blood pressure, heart problems or diabetes) appear to be more vulnerable".

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(Reporting by Claire Cozens, Editing by Katy Migiro and Belinda Goldsmith. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers the lives of people around the world who struggle to live freely or fairly. Visit http://news.trust.org)

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