ACELLULAR PERTUSSIS DIPHTHERIA-TETANUS-PERTUSSIS VACCINE CONTAINING SEPARATELY PURIFIED PERTUSSIS TOXOID, FILAMENTOUS HEMAGGLUTININ AND 69 KDA OUTER-MEMBRANE PROTEIN AS A BOOSTER IN CHILDREN

In two double-blind, randomized, comparative studies involving a total of 218 children, an acellular pertussis (DTPa) vaccine containing dip htheria and tetanus toxoids and pertussis components filamentous haema gglutinin (FHA), pertussis toxoid (PT), and 69 kDa outer membrane prot ein (69 kDa OMP) was administered as a booster to 17-month-old and 5-y ear-old children with a history of routine whole-cell diphtheria-tetan us-pertussis (DTPw) vaccination. The control groups in these studies r eceived DTPw vaccine. Among 17-month-old toddlers, significantly lower proportions of DTPa vaccine recipients had local pain (7.3%), redness (14.5%) and swelling (9.1%) than DTPw vaccine recipients (23.6%, 30.9 % and 23.6%, respectively). A trend toward fewer local reactions was a lso seen in 5-year-old children vaccinated with DTPa in private practi ce and public clinics although differences were not statistically sign ificant. Fever (rectal temperature greater-than-or-equal-to 38-degrees -C) was reported more frequently for DTPw vaccine recipients in both a ge groups. While no differences existed between groups in terms of geo metric mean antibody titres (GMTs) prior to booster vaccination, anti- PT antibody GMTs were higher among DTPa vaccine recipients than among DTPw vaccine recipients after booster vaccination. The difference was statistically significant in 5-year-old subjects. Furthermore, signifi cantly higher anti-FHA and anti-69 kDa OMP GMTs were seen in DTPa vacc ine recipients in both age groups. In pre-vaccination seropositive sub jects and in pre-vaccination seronegative subjects the rate of immune response to pertussis antigens was higher for DTPa than for DTPw vacci ne recipients with the exception of the rate of response induced to 69 kDa OMP in 5-year-old children. The lower frequency of side-effects a nd similar or greater immunogenicity of DTPa vaccine when used as a bo oster in subjects primed with DTPw encourage the introduction of this type of vaccine for the fourth and fifth DTP doses that are routinely administered in many countries.