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Did you know that the flu is different for men and women? But why? The answer lies in how men’s and women’s immune systems respond to the virus; they don’t always respond the same⁽¹⁾.

Why women are better able to fight the flu

Researchers looking into how our immune systems fight the flu noticed that flu severity increases not only as we age but also, for women, during pregnancy⁽¹⁾. Since pregnant women are more susceptible to the virus⁽¹⁾, they suspected the reproductive hormones that fluctuate during pregnancy⁽²⁾ might have a part to play.

Laboratory studies tested cells taken from male and female volunteers’ nasal passages. They showed that the hormone oestrogen does, as suspected, affect the flu virus’s capabilities⁽¹⁾. The virus found it more difficult to infect the cells donated by women than the cells donated by men.

Several laboratory studies using mice have also confirmed that females’ immune systems are better at fighting the flu than males’⁽²⁾⁽³⁾. One study even concluded that female hormones help the body identify and eliminate infections ⁽⁴⁾.

Women respond better to the flu vaccine too

So, is it the same for vaccination? Do men and women also respond differently to the flu vaccine?

Scientists are aware that women tend to have a better immune response to vaccines, and the elderly a weaker one⁽⁵⁾. Researchers exploring these gender- and age-related differences⁽⁶⁾ found that the immune systems of women of reproductive age respond much better to the flu vaccine than the immune systems of men and older women.

The findings, the researchers concluded, suggest that oestrogen helps flu vaccines work better⁽⁵⁾ – and testosterone, the primary male reproductive hormone, hinders them. In other words, the flu vaccine offers women a greater level of protection against the flu⁽⁶⁾, but their advantage disappears as they reach the menopause and their oestrogen levels decline⁽⁵⁾.

The flu shot may be less effective in preventing some from catching the flu, but vaccination will reduce the severity of illness and the risk of complications. We should also remember that it only protects against the flu, not the common cold nor the norovirus ‘winter vomiting bug’ that also commonplace during the colder seasons.

References
(1) https://www.physiology.org/doi/full/10.1152/ajplung.00398.2015
(2) https://ramsresearch.nl/is-the-man-flu-really-worse-than-a-womans-flu/
(3) https://www.sciencedirect.com/science/article/pii/S0264410X11015520
(4) https://www.bmj.com/content/359/bmj.j5560
(5) https://www.jhsph.edu/news/news-releases/2019/womens-stronger-immune-response-to-flu-vaccination-diminishes-with-age.html
(6) https://www.contemporaryobgyn.net/vaccination/age-gender-and-response-flu-vaccination