Immunity, Your Gender, and the Flu

personalfx (sxc.hu)

If you’re worried about how you’ll fare through this year’s flu season, the answer, surprisingly, may depend on whether you are a man or woman. Research on the impact of gender on disease response, including to the flu, is relatively new — in fact, clinical trials at the National Institutes of Health (NIH) didn’t include women until 1993. Prior research (other than on the reproductive system) looked at only the male population, and findings were simply assumed to apply to women. How wrong that was!

 Guys, Gals and the Flu

Sabra Klein, PhD, assistant professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health and coeditor of the recently published book Sex Hormones and Immunity to Infection, is an expert on this topic. She told me that when it comes to the immune system, the differences between the genders don’t play out in the way you might expect. Let’s start with how we’re different:

  •  Genetic differences. Going all the way back to high school biology, we all know that women have two X chromosomes, while men have an X and a Y chromosome… and that the X chromosome carries five to 10 times as many genes as the Y — including genes that result in a more intense immune response.
  • Hormones. Estrogen enhances immune function, while androgen (testosterone) may suppress it. Consequently, women have more reactive immune systems — but, as you’ll see, this doesn’t always work out in women’s favor.

While it might sound as if women have the better end of the immunity deal, the reality is quite different. Here’s how these differences actually unfold in terms of gender immunity responses concerning the flu…

  •  Women and men catch the flu in about equal numbers.
  • Once infected, women usually clear the virus more quickly. However… pandemic or outbreak flu strains, such as the avian flu, may trigger a hyperreactive immune response in women, typically bringing more severe symptoms. For instance, women are more likely to experience severe, possibly even lethal, lung complications.

What You Can Do

Given these findings, Dr. Klein feels that it’s important for women in particular to be vigilant about proper hygienic and other preventive measures and, if your doctor advises it, to get the flu shot (which now protects against H1N1 “swine” flu as well as the regular seasonal flu). One caveat about the shot: Women’s very sensitive immune systems can increase the likelihood of developing minor side effects, including brief inflammation and pain at the site of the injection.

While research shows that a half-dose shot triggers sufficient immune protection with a lower risk for side effects, Dr. Klein said many doctors aren’t yet convinced — she suggests asking your doctor for the lower dose and, if he/she doesn’t think it’s such a great idea, sharing the information that you’ve learned about women’s health and flu vaccines.

Source:  Sabra Klein, PhD, assistant professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, Baltimore, and coeditor of Sex Hormones and Immunity to Infection (Springer).

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