Pertussis: the disease and the vaccine.

PERTUSSIS STILL CAUSES SIGNIFICANT MORBIDITY: average duration of the illness is six to eight weeks. Almost one third of infants have complications including weight loss, apneic spells, otitis media, pneumonia, and seizures. Encephalopathy occurs in approximately one in 2000 infants: one third die and one third sustain permanent brain damage. The mortality rate is one in 1000 infants. Pertussis vaccine consists of heat and formalin-killed whole bacteria. Minor reactions of fever, irritability, crying, and local reactions occur after 40-60% of injections. Major reactions include prolonged screaming, seizures, collapse, fever over 40.5°C, and encephalopathy. Permanent brain damage occurs in association with one in 310,000 injections, so the benefits clearly outweigh the risks. All young children should be immunized.