Background: In France, the only vaccines available for use as a pertussis booster in adults are combined vaccines containing adsorbed tetanus, diphtheria (adult formulation), acellular pertussis and inactivated poliovirus (Tdap-IPV). Adults may require a pertussis booster relatively soon after having received vaccines containing tetanus-diptheria antigens (Td)(occupational or familial circumstances as new job, childbirth in recent past or future), although the safety of Tdap-IPV when administered soon after vaccination with Td is undocumented.

Methods: In this randomized, double-blind, multi-centre study, we assessed the safety of Tdap-IPV administered 1 month after vaccination with tetanus, diphtheria (adult formulation), inactivated poliovirus vaccination (Td-IPV) in healthy adults vaccinated according to the French vaccination calendar (seven tetanus-diphtheria vaccinations by age 18 years). Subjects received either Td-IPV (n = 249) or placebo (n = 251) followed 1 month later by Tdap-IPV. Any adverse events (AEs) were recorded.

Results: The safety of Tdap-IPV was similar when Tdap-IPV vaccine was administered 1 month after either Td-IPV or placebo: at 7 days, 85.1% versus 93.4% subjects reported at least one reaction at the injection site, mainly pain (82.6% versus 92.1%); 40.5% versus 45.0%, at least one systemic AE (mainly headache: 26.4% versus 26.0%); fever concerned 1.7% of both groups. No serious vaccine-related AEs were reported. Both safety profiles corresponded to documented product characteristics.

Conclusions: Tdap-IPV may be administered to adults 1 month after Td-IPV without exacerbating post-vaccination side-effects.