Women react more strongly to flu vaccination than men, a new study has demonstrated, meaning they might be more protected against getting sick. Researchers examined the inflammatory responses of 53 women and 34 men after they got their flu shots, and found that men, particularly men with high testosterone, exhibited less inflammation afterward. While researchers didn't examine whether this made them more likely to get sick, previous research suggests it does, LiveScience reports.
Genetics might also play a role; researchers observed that the shot activated specific genes, and from this they could determine who would react most strongly. The study "reinforces the message that there are major differences between men and women in terms of their immune systems," said one study researcher. One possible reason: Early men may have gotten hurt more often than women, and benefited from weaker inflammatory responses (testosterone suppresses inflammation). Inflammation "is a necessary part of immunity," the researcher said, "but if it gets out of hand, it can kill you." (Read more immunology stories.)