This article appeared on the Washington Post website in January of this year. It’s far and away the best (most useful) thing I’ve read about pneumonia. Couple of excerpts:

One reason is that the detritus from an infection of the lung is hard to clear. Antibiotics kill the bacteria, but all the weaponry your body produced to fight the bacteria — mucus, essentially, or sputum, as it’s called once you cough it up — is left behind. […] Cough is a primary way to clear the gunk. That’s why doctors advise pneumonia patients not to take cough suppressants. You want to get that stuff out.

The energy drain (your body fighting the infection) burns calories and proteins. When illness dampens appetite, that can exacerbate fatigue and weakness. He advises: “Eat good protein and take plenty of calories.”

The flu has been wicked bad this year. Neither Barb nor I have gotten it (so far). We both got flu shots. But my recollection of the flu was you felt like hell for a week (or two) and that was it. I’m here to tell you the aftereffects of pneumonia can drag on for months.