Interchangeability of Hepatitis A boosters, Avaxim® and Vaqta®, in healthy adults following a primary dose of the combined typhoid/Hepatitis A vaccine Viatim®

This study investigated the suitability of Avaxim® and Vaqta® as Hepatitis A booster vaccines 6 months after priming with the combined Hepatitis A/typhoid vaccine, Viatim®. One hundred and twenty adults were randomly assigned to one of the three groups. Group A (reference group) received Avaxim® then Avaxim® (n = 40), Group B received Viatim® then Avaxim® (n = 41) and Group C received Viatim® then Vaqta® (n = 39). One month after booster vaccination, anti-Hepatitis A virus (anti-HAV) antibodies geometric mean concentrations (GMC) of subjects primed with Viatim® were non-inferior to the group primed and boosted with the monovalent Hepatitis A vaccine Avaxim®. Anti-Salmonella typhi capsular polysaccharide virulence antigen (anti-Vi) GMCs in groups primed with Viatim® were protective and all vaccines were well-tolerated. Therefore, Viatim® may be used as a primary HAV vaccine with either Avaxim® or Vaqta® as Hepatitis A boosters and it will provide the same protection as two doses of Avaxim®.