Hong Kong flu outbreak

Recently, there is a flu outbreak in Hong Kong. 3 kids died in the process. School shut down for 2 weeks to halt the flu spread. Some even fear that it is bird flu in disguise. But eventually, it proves to be human flu only.

It seems to me that flu has became a major issue in Asia nowadays. We don't hear the serious flu outbreak often last time. Why it is now happening more frequently? Pollution? Global warming?

I suggest government to promote more healthy lifestyle. Once the immune system is strong, the flu should pose less problem.