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This study compared the long-term persistence of anti-hepatitis A (anti-HAV) and B (anti-HBs) antibodies, 5 years after vaccination of subjects aged 1-11 years with a combined hepatitis A and B vaccine either in a two-dose (0, 6 months, Adult formulation) or a three-dose (0, 1, 6 months, Paediatric formulation) schedule. At the end of the 5 years, all subjects (100%) in both groups continued to have anti-HAV antibodies > or =15mIU/mL, while 94-97% of subjects in both groups had anti-HBs antibody concentrations > or =10mIU/mL. Subjects with anti-HBs antibody concentration < or =10mIU/mL were administered a challenge dose of hepatitis B vaccine. All subjects mounted a vigorous immune response to the challenge indicating the presence of immunological memory to HBV.

This study was conducted to compare the reactogenicity, immunogenicity and safety of a combined two-dose (0, 6 months) hepatitis A and B vaccine (720ELU HAV, 20 mcg HBsAg) with the established three-dose (0, 1 and 6 months) hepatitis A and B vaccine (360ELU HAV, 10 mcg HBsAg). A total of 511 children aged 1-11 years who had not previously received a hepatitis A or B vaccine were enrolled in the study. Both vaccines were well tolerated, and were shown to be safe and immunogenic. The analysis, stratified according to two age groups (1-5 year and 6-11-year-old children) demonstrated that the reactogenicity profile of the two-dose schedule was at least as good as that of the established schedule. Both vaccines and schedules provided at least 98% seroprotection against hepatitis B and 100% seroconversion against hepatitis A, 1 month after the end of the vaccination course (Month 7).

An open, randomised, multicentre trial was performed to compare the reactogenicity and safety profile of the administration of a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated polio (DTPa-HBV-IPV) vaccine administered in one injection mixed with Haemophilus influenzae type b (Hib) conjugate vaccine (Group 1) with that of a pentavalent DTPa-IPV vaccine mixed with a Hib vaccine (DTPa-IPV/Hib), simultaneously administered with HBV (Group 2) in two injections in opposite thighs, as a primary vaccination course, to healthy infants at 2, 4 and 6 months of age. A total of 235 completed the study, 120 from Group 1 and 115 from Group 2. Blood samples (pre-vaccination and 1 month after the third dose) were obtained from a subset of infants (Group 1: 40; Group 2: 31) to assess the immune response to vaccination. Local and general solicited symptoms were recorded by parents on diary cards. Seven hundred and five diary cards (Group 1: 360; Group 2: 345) were collected. The clinically relevant and most commonly reported local reaction was pain (infant cried when the limb was moved) in 2.5% (Group 1) and 1.2% (Group 2) of diary cards. Fever was more frequently reported in Group 1 (21% of diary cards) than in Group 2 (12% of diary cards). However only 3 and 2% of doses in Groups 1 and 2, respectively, were responsible for a rectal temperature between 38.6 and 39.5 degrees C and only one case (Group 2) had > or =39.5 degrees C. Other clinically relevant general symptoms were rarely recorded: irritability (2-2.8%), loss of appetite (0.3-0.6%) and drowsiness (0.3-0.3%). All subjects included in the immunogenicity analysis had seroprotective titres to diphtheria, tetanus, polio virus types 1 and 3, Hib. Almost all subjects were seroprotected for anti-polio type 2 and hepatitis B (with the exception of 1 subject in Group 1 for each antigen). The vaccines response rates to pertussis antigens were over 97 and 90% in Groups 1 and 2, respectively. This study shows that, from a clinical perspective, the DTPa-HBV-IPV/Hib vaccine given in a single injection has a similar reactogenicity and safety profile to that of two licensed vaccines (DTPa-IPV/Hib, HBV) given in two simultaneous injections to infants at 2, 4 and 6 months of age. This is a valuable advantage, since in some countries, such as Spain and the UK, an additional injection (for the administration of meningococcal C conjugate vaccine) has been recently included in the infants' vaccination calendars.