Tuesday, March 17, 2020

Repost: H7N9 sparing Children. Why?


This was a blogpost I wrote in 2013.

The virus know as H7N9 has infected 49 people, killing 11 for a mortality rate of around 23 percent. Included in the 49 infected children, 1 who has been discharged from the hospital and 1 who is reported to be in stable condition in a Beijing hospital. Strange that an infection that leads to a high mortality rate among adults would spare the children it infects unlike most influenza's that strike both the very young and very old with great intensity. Thinking about this I came up with two possible reasons why this should be:

1. That for those infected with H7N9 the worst effects of the disease are not caused by the virus but by the body's own immune system. Adults have very robust immune systems that are capable of mounting a quick and overwhelming response to an antigen, such as a virus like H7N9. (If your wondering exactly what is an immune response, if you or someone has ever had an allergic reaction, that is an immune response. Sometimes it can cause mild symptoms like itching and other times can kill you in minutes unless medical treatment is initiated quickly). Children, on the other hand have, of course, immature immune systems that might not be able to mount such a quick and ferocious response to an agent that invades the body like H7N9 thus a higher rate of survival.

2. I thought of this but can't understand at the moment how it could lead to a less lethal disease in children. What I'm talking about is influenza vaccines. By the time most people are 30 years old they have had a series of flu vaccinations for a slew of different virus strains. Children, in contrast of course have either had no vaccinations or at the most very few. Again, I'm not sure why a virus would be particularly lethal to those who have had more influenza vaccinations than those who have not.

3. It just may be, thank God that not enough children have been infected to gain a complete understanding of the effects of the disease on their age group

What ever the reason China has been fortunate so far in that relatively few children have become infected by this disease and none have died.