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For the period 1980–1989, an increase in the incidence of pertussis was noted for the first time in recent decades with the trend being most pronounced in adolescents and adults. The diagnosis is often missed and the illness is inadequately treated. Whole cell pertussis vaccine remains efficacious in the 1990s; its combination with other vaccines has been achieved. Safety and immunogenicity trials of multi-component and bi-component acellular vaccines demonstrate that they produce much lower rates of injection site and common systemic reactions than whole cell pertussis vaccines. Very high antibody levels are produced to the components in the acellular vaccines; the concentration of the antibody is usually proportional to the quantity of antigen. New efficacy trials of acellular pertussis vaccines in infants are currently underway.