A combined dual-chamber typhoid/hepatitis A vaccine as a booster dose in hepatitis A primed adults.

Vivaxim is a combined hepatitis A/typhoid fever vaccine (HA/Vi) licensed for vaccination of travellers, but long-term protection against hepatitis A requires two immunisations at least 6 months apart. A randomised, controlled study was performed in 116 healthy adults primed with hepatitis A vaccine (Avaxim) to compare immune responses to HA/Vi and Avaxim given as booster doses 6 months later. Both vaccines elicited marked booster responses achieving antibody geometric mean titres (GMTs) of 4576 and 3760 mIU/ml in the HA/Vi and Avaxim groups, respectively. Although twice as frequent in the HA/Vi group, local reactions (mostly pain) were mainly mild and transient, probably reflecting the larger volume injected (1ml). Vivaxim offers a convenient means of administering both HA and typhoid fever vaccines in subjects already primed for hepatitis A.