In January 2014, researchers from the Stanford School of Medicine published a study on testosterone and immunity. They discovered that men with higher levels of testosterone had a reduced immune response to the flu vaccine.
Past research has shown that women often have stronger immune responses to bacterial, viral, fungal, and parasitic infections than men. Women’s responses to certain vaccines, like flu, measles, and hepatitis also tend to be stronger. Scientists are not sure why.
The Stanford study involved 53 women and 34 men of various ages. The participants had been part of ongoing research since 2008. Each year, they had their blood drawn before and after receiving an annual flu vaccine.
To determine the strength of the participants’ immune systems, the researchers looked at levels of antibodies. Antibodies are proteins that fight harmful substances when they enter the body. A flu vaccine contains dead viruses that cannot give a person the flu. However, the body’s immune system still recognizes these killed viruses as threats and builds up antibodies.
The researchers found that the women had a stronger antibody response to the flu vaccine than the men. Men with lower testosterone levels had a similar response.
However, men with higher testosterone levels had a weaker response. The researchers explained that testosterone appears to interact with a particular set of genes called Module 52 genes. This interaction may hinder immune response.
The study was published in the Proceedings of the National Academy of Sciences.