Why Include Both Sexes in Studies

Even though I know my wife and I can be polar opposites, science doesn't treat us that way. Most medical treatments have been developed using males, but we're seeing problems with that universal approach.

For example, thirty years ago the World Health Organization quickly withdrew a new measles vaccine in several countries after infant girls died in clinical trials even though boys were unaffected. In 2000, we learned women with HIV are infected with many different forms of the virus but men just by one. Women also tend to suffer more severe symptoms of the flu in spite of having fewer viruses in their blood.

It's possible women mount a greater immune response resulting in more severe symptoms, but could this amplified response explain why more women get auto-immune diseases? Unfortunately, despite these differences, many studies simply don't use females because menstrual cycles and pregnancy introduce complicating factors.

But now scientists are being encouraged to include both sexes. For example, one study of Gambian infants found girls given a tuberculosis vaccine suppressed production of an anti-inflammatory protein not seen in boys, giving the girls better immune response. In a study comparing men and women with sex changes, scientists plan to see whether the female hormone estrogen activates cells that defend against viruses while the male hormone testosterone suppresses it.

Both US and European granting agencies now require that researchers report the sex of the animals used in pre-clinical trials, however, they don't yet have to report the differences in the results. IF they did, women's healthcare could improve and show just how different we are.