H7N9 avian influenza virus infection in men is associated with testosterone depletion

Very little is known about biological sex differences in influenza disease outcome. In 2013, avian influenza (H7N9) infections in humans have been reported with higher frequency in men than women. Here, Bai et al. report that low testosterone levels in men correlate with poor infection outcome. They confirm the causal link between viral infection and testosterone depletion using a mouse model.