Primary hepatitis A vaccination failure is a rare although possible event: results of a retrospective study

A case of Hepatitis A occurred in a traveller in spite of a complete course of immunization with a combined HAV and HBV vaccine [Taliani G, Sbaragli S, Bartoloni A, Santini MG, Tozzi A, Paradisi F. Hepatitis A vaccine failure: how to treat the threat. Vaccine 2003;21(31):4505–6]. A retrospective study was performed to evaluate whether the failure was primary or could be attributed to a specific lot of vaccine or to its inadequate handling and/or storage. Two distinct populations of vaccinees were selected in a 1:2 proportion. The case group (N = 31) included subjects who were vaccinated in the same period and with the same lot and batch of vaccine as the case. The control group (N = 62) included subjects who received different lot and batch of the same vaccine as the case group. A persisting antibody response to HAV vaccine was found among all subjects (anti-HAV >20 mIU/ml). The overall anti-HBs seropositivity rate (anti-HBs >10 mIU/ml) was 74%, without significant difference between the case (77%) and the control group (73%; P > 0.05). The reported Hepatitis A case can be attributed to a rare primary vaccine failure rather than to inefficacy of a specific lot of vaccine or to inappropriate vaccine handling or storage. Our study supports the indications for use of combined Hepatitis A + B immunization in travellers at risk for both infections, but stresses the need for information on correct hygienic behaviours while abroad.