It's one of the pandemic's prolonged mysteries: Why have men died of COVID-19 at higher rates than women?
COVID fatality rate for men was 1.7 times higher, on average, than the rate for women across 38 countries, a 2020 study found. More recent research from Harvard University scientists found that although men represented 49 percent of COVID cases in the U.S., they accounted for 55 percent of COVID deaths from April 2020 through May 2021.
This week, a study lent further support to a leading theory about the discrepancy: Estrogen may offer some protection against severe COVID.
For the study, published in the journal Family Practice, U.K., researchers compared women in England who had received hormone replacement therapy — which helps restore estrogen levels during menopause — within six months of a COVID diagnosis to those who did not. The results showed that the first group had a 78 percent lower mortality rate from all causes of death than the second group.
Get top local stories in Southern California delivered to you every morning. Sign up for NBC LA's News Headlines newsletter.
"This is adding to the body of evidence of why, particularly early in the pandemic, we were seeing really different clinical outcomes for women relative to men," said Anita Raj, a professor of infectious diseases and global public health at the University of California, San Diego, who was not involved in the research.