Control of pertussis--lessons learnt from a 10-year surveillance programme in Sweden.

Sweden was the only country in the world without any general pertussis vaccination when acellular pertussis (aP) vaccines were introduced. Since 1996 aP vaccines are given at the ages of 3, 5 and 12 months, with a 99% coverage, and until 2007 without a later booster. The long-term effects of aP vaccines, monitored within an enhanced surveillance project, were discussed at an international workshop in Stockholm in November 2008. The unique Swedish experience demonstrates that aP vaccines are capable of achieving the primary goal of a national vaccination programme, i.e., to significantly reduce the burden of pertussis in pre-school children. Throughout the 10-year surveillance period the highest age-specific incidence was reported in unvaccinated infants or those who had received only one dose, with most hospitalisations in this age group and eight deaths among unvaccinated infants. Complementary strategies are needed to achieve further reduction in morbidity from circulation of Bordetella pertussis.