Effect of vaccination on Bordetella pertussis strains, China

Whole-cell pertussis vaccine was introduced in China in the early 1960s. We used standard typing methods to compare 96 Bordetella pertussis isolates collected before and after introduction of vaccination, during 1953-2005. The following vaccine-type alleles of the pertussis toxin (ptx) gene were characteristic for all prevaccination strains: ptxA2, ptxA3, and ptxA4. The shift to ptxA1 occurred since 1963. All isolates collected since 1983 contained ptxA1. Pertactin (prn) allele 1, prn1, was predominant, although prn2 and prn3 have been detected since 2000. Serotypes fimbriae (Fim) 2 and Fim2,3 were found in all isolates collected before 1986. During 1997-2005, Fim3 became prevalent. Although changes in electrophoresis profiles over time were observed, the predominant profiles during 1997-2005 resembled those during the prevaccine era and those found in Europe before the 1990s. B. pertussis strains in China may differ from those in countries that have a long history of high vaccine coverage.