I am careful to never forget to get my flu shot in mid October and I have not had the flu since I have been doing that.
Yes, pneumonia is the killer of older people. Once it gets to an advanced stage our immune systems are too weakened to fight if off like when we were younger. I never ignore a cold or influenza and begin treating it as soon as the symptoms appear.
In my case, the flu shots don’t seem to help that much so I try to keep my immune system healthy through moderate daily exercise and good nutrition. I am way past my expiration date, so like Forest Gump I just keep moving and doing the things that I think are right for me. So far, so good, but time changes everything as we age.