SAFETY AND IMMUNOGENICITY OF A COMBINED DIPHTHERIA-TETANUS-ACELLULAR PERTUSSIS-HEPATITIS-B VACCINE ADMINISTERED ACCORDING TO 2 DIFFERENT PRIMARY VACCINATION SCHEDULES

The reactogenicity and immunogenicity of a tetravalent diphtheria-teta nus-acellular pertussis-hepatitis B (DTPa-HB) vaccine (SmithKline Beec ham) were studied in 565 infants immunized according to one of two dif ferent schedules, at 2, 4 and 6 months Of age (group A n = 208) or at 3, 5 and 11 months of age (group B n = 357). The incidences of local a nd general reactions within the first 8 days after vaccination were si milar in the two groups of infants, the vast majority being mild in in tensity and occurring within 2-3 days of vaccine administration. Sever e local symptoms were rare. pain after 0.6% of all doses, redness afte r 0.5% and 1.3%, and swelling after 0.3% and 1.5%, in group A and B, r espectively. Only one infant in group A and one in group B had a tempe rature > 39.0 degrees C. Both schedules proved satisfactory in obtaini ng high levels of antibodies against all antigens. The rates of serolo gic response against the different antigens reached 100% in both group s. Antibody titres against all vaccine components were elevated follow ing both schedules, but after the third dose of vaccine geometric mean antibody titres (GMTs) against D toxoid, filamentous haemagglutinin ( FHA), pertactin (PRN) and hepatitis B (HB) were significantly higher i n the 3, 5, 11 group than after the 2, 4, 6 schedule. Antibody titres measured at 7 months of age in the group immunized at 2, 4 and 6 month s were higher than those reached at 6 months of age in infants immuniz ed at 3, 5 and 11 months, but FHA and PRN were within the range of a D TPa vaccine with proven efficacy. We conclude that DTPa-HB vaccine was safe, well tolerated and highly immunogenic. Both vaccination schedul es (2, 4, 6 and 3, 5, 11) can be considered suitable for mass immuniza tion programmes. (C) 1998 Elsevier Science Ltd. All rights reserved.