Credit ECDC H7N9 Rapid Risk Assessment Feb 2014
# 8269
Last Monday, in H7N9: A Mid-Season Look At Two Waves, I mentioned that we are starting to see some younger cases and slightly more females during this second wave than we did last spring, although cases remain heavily skewed towards older males males.
Today, Dr. Ian Mackay delves much deeper into the latest numbers, and discusses some possible reasons for the changing demographics of infection.
Click on image to enlarge.
Age groups selected to convey clearest trends
without too many lines.A quick look at some age bands followed each week during the course of both waves of the avian influenza A( H7N9) virus outbreak.
The interesting line to watch is that of the youngest age group (0-19-years) which has lifted to comprise 50% of cases in the week beginning 27-Jan. Also, the proportion of cases in the oldest age group (70->90-years) has dropped down in the past 2 weeks.There have been a rash of children in recent announcements; 8 of the last 45 cases have been <10-years of age. For a virus with a median case age sitting at 58-years, this is quite a departure.
Is this due to an increase in familial clusters? Does it herald a shift in the way the virus is spreading? Intrafamilial transmission may provide a hint at increasing transmission efficiency. It might also be a sign of increased testing augmenting clinical observation of close contacts of ill family members.
