Developments in pertussis immunisation in Japan.

In Japan acellular pertussis vaccine has totally replaced whole-cell vaccine since 1981. The vaccine is given in combination with diphtheria and tetanus toxoids to children aged 24-48 months; three doses are given with intervals of 3-8 weeks and the fourth dose (booster) is given 12-18 months after the third. There has been a steady decline in cases of pertussis and deaths from the disease since 1979. Comparison of the rates of adverse reactions to whole-cell vaccine in 1973-74 and to acellular vaccine in 1979-80 showed lower rates of fever and of local reactions with the acellular vaccine.