Flu Vaccine may be Less Effective in Men than Women: Study

A recent study shows that the flu vaccine may be less effective in men than women. 

Findings suggests that higher levels of testosterone could curb an immune response and cause the body to ineffectively accept the vaccine. 

As previous studies have shown that men are more prone to bacterial, viral and parasitic infections, scientists have not been able to clearly explain why. 

New research that used samples from 34 men and 53 women suggests that the cause for this health issue may be traced to hormones. For instance, as men carry much higher levels of testosterone than women, the immune response may use "more or less equivalent to that of women," according to a statement from Stanford University, whose researchers collaborated with others at the French governmental research organization INSERM for the study.

The latest findings show a direct link between testosterone and a lowered immune response. In fact, the study notes that the immune system's reaction was reduced by activation of a group of genes that are also linked to a higher level of testosterone, according to immunology professor from Stanford University, Mark Davis. 

Researchers speculate that from prehistoric times, men's roles as hunters and warriors exposed them to more wounds that may have resulted in higher rates of infection. 

Building up an immune responses may provide an evolutionary advantage. However, an overly abundant amount of this can prove to be dangerous and may be causing today's vaccine to be less effective in men. 

More information regarding the study can be found via the journal Proceedings of the National Academy of Sciences.