Immunogenicity and reactogenicity of acellular pertussis booster vaccines in children: standard pediatric versus a reduced-antigen content formulation.

Booster vaccination with a reduced-antigen-content dTpa, pediatric DTPa or adult Td vaccine in DTPa-primed children aged 4-6 years was evaluated. Immunogenicity and CMI was assessed one month and 3.5 years after vaccination. Symptoms were solicited for 15 days post-vaccination. There were no differences between groups in diphtheria or tetanus seroprotection or pertussis vaccine-response rates. Anti-diphtheria and anti-PRN concentrations were higher after DTPa, but groups differences reduced over time. Non-significant trends toward reduced reactogenicity of dTpa were observed. Many factors influence vaccine choice at pre-school age. The dTpa vaccine was as immunogenic and possibly better tol…