Classicly

Pneumonia appears to be spread from person to person by contact, so it is regarded as a communicable disease. As it is contagious, the spread of infection can be stopped if precautions are taken to prevent the transfer of the infectious material from the sick to the well. The secretions from the nose and throat of persons sick with pneumonia, or convalescing from the disease, usually carry the germs that cause it. The transfer may take place through direct contact with these secretions, or inhaling droplets of moist sputum expelled by the sick person while coughing or sneezing.

Pneumonia is no respecter of persons. It may attack tiny babies, adults in the prime of life, or elderly people: so everyone must be on guard. This is especially true in late winter and early spring when the disease is most likely to occur.