Hepatitis A Prevention, Immunization : Side Effects

by CDC

(Page 10 of 13)

Data on adverse events are derived from prelicensure clinical studies worldwide, reports following licensure of HAVRIX in Europe and Asia, other postlicensure studies, and reports to the national Vaccine Adverse Events Reporting System (VAERS) following licensure of HAVRIX and VAQTA in the United States.

Local Reactions

Approximately 50,000 persons were administered HAVRIX in prelicensure clinical studies. No serious adverse events were attributed definitively to hepatitis A vaccine. Among adults, the most frequently reported side effects occurring < 3 days after the 1,440-EL.U. dose were soreness at the injection site (56%), headache (14%), and malaise (7%). In clinical studies among children, the most frequently reported side effects were soreness at the injection site (15%), feeding problems (8%), headache (4%), and injection-site induration (4%). The frequency of side effects after administration of TWINRIX was similar to those reported when the two single-antigen vaccines were administered.

Approximately 10,000 persons were administered VAQTA in prelicensure clinical studies, and no serious adverse events were reported among participants. Among adults, the most frequent side effects that occurred < 5 days after vaccination included tenderness (53%), pain (51%), and warmth (17%) at the injection site and headache (16%). Among children, the most common side effects reported were pain (19%), tenderness (17%), and warmth (9%) at the injection site. In one placebo-controlled trial among children, adverse reactions among vaccine recipients did not differ substantially from those that occurred among persons who received placebo.

Serious Adverse Events

An estimated 1.3 million persons in Europe and Asia were vaccinated with HAVRIX before the vaccine's licensure in the United States in 1995. Reports of serious adverse events, without regard to causality, received by the vaccine manufacturer included anaphylaxis, Guillain-Barré syndrome, brachial plexus neuropathy, transverse myelitis, multiple sclerosis, encephalopathy, and erythema multiforme. The majority of these events occurred among adults, and approximately one third occurred among persons receiving other vaccines concurrently. For serious adverse events for which background incidence data can be estimated (e.g., Guillain-Barré syndrome and brachial plexus neuropathy), rates for vaccine recipients were not higher than would be expected for an unvaccinated population.

No serious adverse events were reported for approximately 40,000 children who were administered the 360-EL.U. dose of HAVRIX in the protective efficacy study. In a postlicensure study of 11,417 children and 25,023 adults who were administered VAQTA, no serious adverse events occurred that were considered to be associated with administration of vaccine. A published postlicensure evaluation of safety among 2,000 child and adult recipients identified no serious adverse events associated with VAQTA.

Since vaccine licensure in 1995, approximately 188 million doses of hepatitis A vaccine have been sold worldwide, including 50 million doses in the United States. During January 1995 - October 2005, VAERS received 6,136 reports of adverse events among persons who received hepatitis A vaccine, with or without other vaccines. The most common events were fever, injection-site reactions, rash, and headache. The 871 reports of serious adverse events included reports of Guillain-Barré syndrome, transaminitis, and idiopathic thrombocytopenic purpura, which had been described previously in a published safety review, and seizures among children. The relation, if any, between the vaccine and reported serious events was not clear. In the original safety review, reported adverse events were similar for VAQTA and HAVRIX. The safety of the vaccine will continue to be assessed through ongoing monitoring of data from VAERS and other surveillance systems.

Contraindications and Precautions

Hepatitis A vaccine should not be administered to persons with a history of a severe allergic reaction to a previous dose of hepatitis A vaccine or to a vaccine component. The safety of hepatitis A vaccination during pregnancy has not been determined; however, because hepatitis A vaccine is produced from inactivated HAV, the theoretic risk to the developing fetus is expected to be low. The risk associated with vaccination should be weighed against the risk for hepatitis A in pregnant women who might be at high risk for exposure to HAV. Because hepatitis A vaccine is inactivated, no special precautions need to be taken when vaccinating immunocompromised persons.

About the Author

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