Hepatitis A virus (HAV) infection is common in industrialized and developing countries. While HAV infection is associated with a low mortality rate, the virus can produce significant morbidity among infected persons. The risk of death in persons with HAV infection increases with advancing age and in patients with underlying liver disease from chronic hepatitis B or C virus infection. One study found that 35 percent of patients with hepatitis C died after developing HAV infection. A high prevalence of hepatitis B and C virus infection has been noted among many transplant recipients. These patients are also immunosupressed because of the chronic use of medications such as steroids and cyclosporine. Stark and colleagues studied the efficacy and safety of hepatitis A vaccine in organ transplant recipients.

Study participants were at least 18 years of age, had undergone liver or kidney transplantation and were negative for antibodies to HAV and human immunodeficiency virus. All eligible participants received two doses of the hepatitis A vaccine six months apart. Follow-up qualitative and quantitative antibody titers were obtained after both doses of the vaccine were administered.

Researchers enrolled 104 patients in the study, including 39 patients who had liver transplants, 39 patients who had kidney transplants and 29 control patients. The mean age of the patients was 48 years, and the distribution of men and women was nearly equal. Most of the liver transplant recipients were taking only one immunosuppressive medication, while all of the kidney transplant recipients were taking two or more immunosuppressive agents. The median time interval from organ transplantation was 40 months for the liver transplant recipients and 96 months for the renal transplant recipients. Forty-one percent of the liver transplant recipients had undergone surgery because of chronic hepatitis B or C virus infection. Ten percent of the renal transplant recipients had serologic evidence of chronic hepatitis B virus infection, and 28 percent had evidence of chronic hepatitis C virus infection.

Anti-hepatitis A virus seroconversion occurred in 41 percent of the liver transplant recipients, 24 percent of the renal transplant recipients and 90 percent of the control subjects after one dose of the vaccine. Four weeks after the second dose was given, the rates of response rose to 97, 72 and 100 percent, respectively. The results were similar between the liver transplant recipient and control groups in regard to mean antibody titers; however, mean antibody titers were significantly lower among the renal transplant recipients. A difference in overall and mean seroconversion rates was noted among patients who took only one immunosuppressive agent compared with patients who took two or three such medications. The mean antibody titers were 1,340 mIU per mL for monotherapy, 136 mIU per mL for double therapy and 88 mIU per mL for triple therapy. Side effects reported by patients included pain at the injection site (33 percent), mild fatigue (14 percent), headache (10 percent) and fever (3 percent). Of note, the control patients reported the largest number of side effects.

The authors conclude that the administration of hepatitis A vaccine is safe and immunogenic in kidney or liver transplant recipients. Two doses of the vaccine are required to attain optimal benefit. The degree of responsiveness was greater in the liver transplant recipients, probably because they used fewer immunosuppressive drugs. The authors recommend that transplant recipients who have chronic hepatitis B or C virus infection or who are highly exposed to hepatitis A be given the hepatitis A vaccine.