My father, 87, had pneumonia over a year and a half ago (one of the most common kinds according to blood tests afterwards) and he was declared to be ok within two months (clear x-rays, no congestion, cough or sign
in blood tests) Yet he has had trouble recovering his full strength
in these last 18 months, and has had a condition that has plagued him, on and off, since then. The condition involves a sensitivity to cold - if he gets in a draft, he starts to overheat from the inside.