Comparative evaluation of the immunogenicity of combined hepatitis A and B vaccine by a prospective and retrospective trial.

In the past, immunogenicity of hepatitis A and B vaccines needed to be questioned in persons of advanced age, especially in those of 40 years and older. We performed a comparative multicenter prospective and retrospective study with the combined hepatitis A and B vaccine Twinrix to identify factors influencing the results of the vaccination in a population of all age groups. Out of 489 subjects enrolled, 241 were vaccinated in a prospective study (group 1) and 248 subjects in a retrospective study (group 2) in 17 German centers with median age of 40.1 (14-79) years. Following three applications of the combined hepatitis A/B vaccine we found 96.2% with protective antibodies against HAV and 88.7% were protected against HBV. With increasing age the subjects developed decreasing anti-HBs antibody levels whereas the seroprotection rate was significantly reduced by age (p < 0.05) in the retrospective study group only. Subjects with arterial hypertension and thyroid disease showed significantly decreased protection rates. The timing of the HBV antibody control seems to be important especially in low-responders because protective antibodies may drop below the detection limit within some month. The combined hepatitis A and B vaccine Twinrix proved to be highly effective against HBV, although antibody concentrations and seroprotection rates decreased with increasing age.