H7N9 and the tendency for males to predominate in case and fatality numbers.

The H7N9 graphs highlight that cases and deaths are occurring in males more than females. We often see more males than females in hospital presentations for acute respiratory illnesses. Why this is so is not known for certain.

Published research from Prof John Upham in Queensland, Australia shows a difference in the immune response to rhinovirus, the virus responsible for triggering most asthma attacks, between males and females in that females stronger response cleans up the virus, probably related to sex hormones. 

This was supported by research from Dr Scotland in London, United Kingdom who found that female mice had more white blood cells and that these were more effective and less over-reactive than male cells in responding to invaders. 

Perhaps this can be extended to influenzavirus infections also.