Officially, the Center for Disease Control and Prevention (CDC) recommends that pneumonia vaccine be made available to protect against pneumonia in all people over 65 years old, even if they
suffer from diseases that weaken the immune system.
Regarding your statement about a "bad reaction" from this vaccine, it has been my experience that this shot is well tolerated in most people. I work in a long term care facility, where this vaccine is given to almost every patient we have, and I have only seen one allergic reaction to it in all my years of practice (I have been here 11 years). Also, all of my patients are frail, very elderly, and above the age of 85. Generally, most people experience some soreness, redness or swelling at the injection site, but this will go away in a few days. Only a handful of people get fever, general muscle pain, or a sore lump at the place the vaccine was given.
Hope this helps!