The Impact Of Sex Steroids On Influenza Vaccine Responses

As women tend to have a greater immune responses to a flu vaccination compared to men; but their advantage largely disappears as they age and their estrogen levels decline; In general, adaptive immune response to vaccines are lower in both aging males and females; as compared with their younger adult counterparts.

The evaluating responses to the flu vaccine in 50 adults age 18-45 years and 95 adults age 65 and older; and found that the women in the younger group had a stronger immune response compared to the older women and all men.

Experiments in mice yielded similar results, and suggested that estrogen levels of which lessen with age in females boosts females’ immune responses to flu vaccines; while testosterone lowers males responses. The scientists expect that their results will be generalizable to other vaccines. Influenza vaccines are recommending for all individuals aging 6 months and older and are administering annually.

Influenza vaccine responses

The immune responses to the 2009 H1N1 influenza vaccine in 145 human volunteers 1 group age 18-45 years, the other 65 and older. The researchers finding that, on average; women in the younger group had a stronger response comparing to both the men and the older women.

The younger women had, for example, a jump in their levels of the important immune protein IL-6 that was almost three times greater than that seen in the younger men; and almost double that seen in older women. Measures of the anti-flu antibody response also were higher for the younger women comparing to the men and the older women; though the greatest differences were between the younger and older women.

Vaccine-inducing antibody

In the human volunteers, the younger females, as expected, had higher bloodstream levels of estradiol; one of the important estrogens, compared to the older, post-menopausal females. Similarly, the younger males had higher bloodstream levels of testosterone compared to the older males.

A stronger vaccine response was linking to higher estradiol among the females and; more weakly, to lower testosterone among the younger males. Vaccine-inducing antibody responses were increasing in females by estradiol and decreased in males by testosterone. The benefit of elevating estradiol on antibody responses; and protection against influenza in females is diminished with age in both mice and humans.