Efficacy of inactivated Mycoplasma pneumoniae vaccine in man.

Inactivated Mycoplasma pneumoniae vaccine produced antibody responses that reached protective levels in most individuals. These were almost equivalent to natural infection in amount and duration, and they persisted more than a year. Adverse effects were inconsequential. At Keesler Air Force Base, Mississippi, where the annual rate of mycoplasma pneumonia varied from 20 to 50 per 1000 since 1959, protection studies were conducted in 21, 199 men in 1964-1966 and in 13, 892 men in 1969-1971. This produced a 36 percent reduction in bronchitis and a 45 percent reduction in pneumonia due to all etiologies in the frist study and 37 percent and 48 percent respectively in the second study. The protective efficacy of the second vaccine was 87 percent for acutebronchitis and 66 percent for pneumonia due to Mycoplasma pneumoniae. Persons who developed Mycoplasma pneumoniae infections in spite of vaccination did not experience more severe illnesses.