An open study of subcutaneous administration of inactivated hepatitis A vaccine (VAQTA®) in adults: Safety, tolerability, and immunogenicity

Abstract

A number of patients in clinical practice would be candidates for hepatitis A vaccine administered subcutaneously (SC), including patients with inherited and acquired coagulopathies. To assess the safety, tolerability, and immunogenicity of VAQTA® (Hepatitis A Vaccine, Inactivated, Merck and Co. Inc., West Point, PA) was administered SC to healthy adults. A total of 114 healthy adults received two doses of vaccine SC 24 weeks apart. No serious vaccine-related adverse experiences were reported. Four weeks after dose 1, the seropositivity rate (SPR) was 77.9% (CI, 69.1, 85.1%). The geometric mean titer (GMT) was 21.0 mIU/ml. Twenty-four weeks after dose 1 (just prior to dose 2) and 28 weeks after dose 1(four weeks following dose 2), the SPR were 95.3 and 100%, respectively; the GMTs were 153.2 and 1563.9 mIU/ml, respectively. Although the kinetics of the immune response were slower when VAQTA® was administered SC compared to intramuscular injection, SPRs and GMTs increased over time, indicating that the vaccine administered SC demonstrated immunogenicity. © 2001 Elsevier Science Ltd.