According to the American Lung Association:
Until 1936, pneumonia was the No.1 cause of death in the U.S. Since then, the use of antibiotics brought it under control. In 2003, pneumonia and influenza combined ranked as the seventh leading cause of death.
This certainly appears to confirm the two-word answer I received from my doctor about dealing with pneumonia before antibiotics.
Confirms sort of. The 1917 flu virus killed by pneumonia, and the viral flus that kill old people every year kill by pneumonia, and antibiotics aren’t any good for viruses. But lethal viral pneumonia seems to be at least intermittently rare. Antibiotics couldn’t have reduced pneumonia deaths much if most lethal pneumonias were viral.