By Nadia Kounang, CNN
While some may consider women “the fairer sex,” science says otherwise.
It’s been known that women, in general, have stronger immune systems. Researchers say males have more bacterial, viral, fungal and parasitic reactions than females, as well as more severe reactions, and women have a “more robust response to antigenic challenges such as infection and vaccination,” according to a new study published Monday.
Why women have stronger immune reactions hasn’t always been clear. But the new study, published in the Proceedings of the National Academy of Sciences, finds it may have something to do with testosterone.
The study measured the antibody responses of 53 men and 34 women of varying ages to the flu vaccine. The study authors found that after the vaccine, women had increased antibody responses as well as higher inflammation cytokine counts. Cytokines are molecules that help guide cells in their immune response.
Study authors traced the increased activity to a set of genes regulated by testosterone; the more testosterone, the weaker the immune response.
While on the outset, that doesn’t sound like good news for men, the authors hypothesized that this may actually be evolutionary.
Women are more likely to develop immune-related issues and are at higher risks for autoimmune diseases. For example, women with the flu more frequently suffer from an overproduction of cytokines, or cytokine storm, which can lead to lung failure. Men are less likely to experience cytokine storm, or other immune-related issues.
This holds true throughout the animal kingdom. Testosterone has been found to help animals manage pain better, while low cytokine count has been related to decreased mortality in mice.
As the authors explained, “males of many species are more likely to experience trauma than females. This positive effect of testosterone may also help to balance out the consequences of reduced immunity to infection.”
Flu vaccines are still recommended, however. CDC Director Dr. Tom Frieden said earlier this month that last year’s flu vaccine is estimated to have prevented 6.6 million people from getting sick with the flu, 3.2 million doctor visits and at least 79,000 hospitalizations.