1. It is cross-reactive with the strain that emerged to dominate, so still provides some , although not full, protection against it.
2. Every spring the CDC looks at which flu strain appears to be dominating in order to predict which vaccine will be effective against the broadest population. They make that decision in the spring in order to give time for the manufacturers to gear up to mass produce the vaccine. And the vast majority of the time, that strategy works.
This past spring, the strain that has ended up dominating turned up in only 3% of cases, so when they made the choice of vaccine they went with the strain that was identified 97% of the time. A few months later, the 3% strain unexpectedly took off and by August it was nearing 50% of cases, so it's not surprising that it has now surpassed 50%.
Most years they get it right. This time they missed, but this wasn't a mess up, it was nature not following its usual path. It happens now and then.
The deaths continue to be those who's immune systems are either not fully developed (children), worn out (elderly) or compromised.
In the past, I relied on herd immunity. Since I started working in health care, the vaccine pretty much required (in my hospital you can still say no, but they make that increasingly cumbersome. Since I've been getting it, I find I'm less inclined to get even colds during flu season. 
Edit history
Recommendations
0 members have recommended this reply (displayed in chronological order):
= new reply since forum marked as read