Impact of vaccination on selected diseases in Canada.

Vaccination has dramatically reduced the morbidity and mortality rates of a number of diseases. The crucial element of vaccination programs is commitment to widespread coverage and to containment of outbreaks. Vaccines have led to virtual elimination of poliomyelitis and promise to eliminate measles. The incidence of congenital rubella syndrome will probably only be diminished if vaccination is extended to all 1-year-olds and susceptible prepubertal girls. The employment of diphtheria toxoid is one of the great success stories in public health. The incidence of pertussis has declined because of the diphtheria-pertussis-tetanus (DPT) vaccine given to infants, although elimination of the disease will probably have to await development of a more potent pertussis antigen. A remarkable reduction in the incidence of tetanus and tuberculosis has also been achieved.