Hepatitis A Vaccine Stems Outbreaks

Hepatitis A is a highly contagious disease spread by the fecal-oral route through close person-to-person contact or ingestion of contaminated food or water.

ANCHORAGE, Alaska, Sept. 17 PRNewswire: The use of a hepatitis A vaccine, inactivated (Havrix(R)) by public-health officials in Alaska indicates that the vaccine can halt outbreaks and prevent epidemics of hepatitis A, according to a study reported in the Archives of Pediatric and Adolescent Medicine (A).

The study was initiated amid outbreaks of hepatitis A in Alaska that began in 1992. In the 12 months preceding the start of vaccination, 443 laboratory- confirmed cases of hepatitis A resulting in jaundice had been reported in rural communities in the interior of Alaska and along the Bering Sea and Arctic Ocean coasts.

Hepatitis A vaccine, inactivated (Havrix) was therefore offered to all eligible persons in 25 communities where there had been documented cases of hepatitis A. By the end of the study, 4,930 persons, of whom 3,517 were younger than 20 years, had received one dose of the vaccine.

In an editor’s note accompanying the report in Archives of Pediatric and Adolescent Medicine, Catherine D. DeAngelis, MD said, “We’re proud to publish proof that prevention practices produce profound performances.”

The authors of the report — health officials at the Indian Health Service, the Alaska Department of Health and Social Services, and the Centers for Disease Control and Prevention — conclude that the curtailment of the Alaskan outbreaks apparently achieved by vaccination could have application elsewhere as well. They say the results suggest that use of only one dose per person of inactivated hepatitis A vaccine alone could not only halt established outbreaks of hepatitis A, if a sufficient portion of susceptible persons are vaccinated, but also prevent an epidemic from becoming established in communities where a few cases of hepatitis A infection have occurred.

On the basis of the historical experience in Alaska, where epidemics of hepatitis A have been observed every 8 to 12 years since the 1960s, the authors estimate that the outbreaks would have lasted 9 to 12 months in each community if no vaccination had been offered. Following vaccination, however, the outbreaks were considerably shorter.

Among 11 villages surrounding the town of Kotzebue, for example, where 80 percent of eligible persons were vaccinated, outbreaks of hepatitis A ceased in 4 to 8 weeks, irrespective of whether the villages were at the beginning, middle, or end of their respective outbreaks.

The number of confirmed cases of hepatitis A reported in all communities participating in this project dropped markedly within the first few weeks after vaccination; the decrease was sustained during the 60 weeks of follow-up,” the authors report.

Moreover, the duration of outbreaks appeared to correlate with rates of vaccination. In Kotzebue itself, where only 49 percent of eligible persons were vaccinated, the outbreak among unvaccinated persons continued for more than 10 months.

In explanation of the varying results between Kotzebue and the surrounding villages, the authors say: “Our experience in Kotzebue suggests that, although vaccination of 50 percent of eligible persons in a community undergoing a hepatitis A epidemic provided protection in vacinees, enough susceptible persons remain in the community to allow the epidemic to continue.”

The study found the hepatitis A vaccine, inactivated (Havrix) to be well-tolerated. The most common adverse event was soreness at the injection site, reported by 23 percent of those vaccinated. As with all vaccines, expanded commercial use could reveal adverse events not observed in clinical trials.(A)

Hepatitis A is a highly contagious disease spread by the fecal-oral route through close person-to-person contact or ingestion of contaminated food or water. Symptoms in adults and adolescents, include jaundice, fever, vomiting, diarrhea, rash, and joint pain. On average, adults miss 30 days of work. Young children tend to suffer only flu-like symptoms, if any, but infection of children can initiate and perpetuate community-wide outbreaks.

Until the outbreaks, beginning in 1992, health officials in Alaska relied upon the administration of immune globulin, which offers fast but short-lived protection against the hepatitis A virus. This measure reduced the incidence of hepatitis A only temporarily and failed to stop outbreaks from growing. Accordingly, the authorities used the hepatitis A vaccine, inactivated (Havrix) without concurrent administration of immune globulin in their effort to stop the outbreaks that had begun in 1992. The study was approved by several institutional review boards and other health authorities; informed consent was obtained by all participants before enrollment.

The single doses of hepatitis A vaccine, inactivated (Havrix) used in the study — 1440 EL.U./mL for those 20 years of age or older, and 720 EL.U./O.5 mL for those under 20 — are now licensed doses in the United States. A booster dose administered 6 to 12 months after the primary dose is recommended to extend protection. Health officials conducting the study in Alaska began administering a second dose in November 1995 and plan to complete administration of the second dose in 1996. (A dose of hepatitis A vaccine, inactivated (Havrix) of 360 EL.U./.05 mL for children and adolescents is also available in the U.S. Two primary doses of 360 EL.U./O.5 mL each are required, separated by a 1 month interval and followed by a booster dose of 360 EL.U./O.5 mL 6 to 12 months after the first primary dose.)

Havrix (hepatitis A vaccine, inactivated), licensed in the United States in February 1995, is licensed in more than 50 other countries as well. The product is manufactured by SmithKline Beecham Biologicals, a unit of SmithKline Beecham. Another hepatitis A vaccine was licensed in 1996.

The study was conducted without financial support from any pharmaceutical company.

(A) McMahon BJ, Beller M, Williams J, Schloss M, Tanttila H, Bulkow L. A Program to Control an Outbreak of Hepatitis A in Alaska by Using an Inactivated Hepatitis A Vaccine. Archives of Pediatric and Adolescent Medicine, July 1996; 150: 733-739.

SOURCE Department of Health & Human Services

[09-17-96 at 16:27 EDT, PR Newswire]

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