We’ve learned a lot about Covid-19 since this novel coronavirus first emerged in China in early 2020. We learned early that the elderly are much more at risk than the young. Now we know men are at higher risk than women.

Jon Kamp and Jason Douglas write of this new revelation in The Wall Street Journal. They state that in the U.S., federal data show men represent about two-thirds of Covid-19 deaths among middle-aged people, and similar trends have emerged overseas. This may be related to higher incidences of comorbidities like high blood pressure and diabetes in men than women.

There may be other factors such as better immune systems in women. Research has shown men are more prone to poor hand hygiene, lax mask wearing habits and delaying medical care. “This is more than a significant trend. This clearly is a reality that this disease is more aggressive in men than women, “ said Lawrence Young, professor of molecular oncology at the University of Warwick, in England.

Women have been hit hard by Covid-19 too, especially in the elderly. U.S. death-certificate data show women make up about 60% of all Covid-19 deaths among people at least 85 years old, the most affected age group. This may, in part, be explained by the fact that fewer men are alive at that age than women. Many of these women are living in nursing homes which have been devastated by Covid-19 outbreaks.

Overall, men make up about 54% of U.S. deaths, and a significantly higher portion in middle age. Men make up nearly 66% of more than 42,000 Covid-19 deaths occurring among people between their mid-30s and mid-60s.

The European data for men are worse. In Europe, the European Center for Disease Prevention and Control says men represent 73% of deaths of those from 40 to 69 years old. Data there also show men are 62% of the hospitalized population aged 40 to 69, and nearly three-quarters of the sickest patients in that age bracket.

Kamp and Douglas say, “More broadly, a global database effort spanning 183 countries called the Sex, Gender and Covid-19 Project based at University College London found about 11 known Covid-19 cases among males for every 10 cases among females, and 14 male deaths for every 10 female deaths. There are some variations within these trends, and some countries aren’t reporting detailed sex-based data, which researchers say is sorely needed to help identify risks.

The chance for severe illness and death with Covid-19 rises steeply with age but is also closely tied to a person’s underlying health. Multiple studies have found people with conditions including diabetes, cardiovascular disease and hypertension tend to be at greater risk of a bad outcome if they catch the virus—conditions that men are more likely to have in general, or at earlier ages.”