OKLAHOMA CITY, Okla. - A growing number of states are requiring hepatitis B (HepB) immunizations for school entry, but beginning in November, Oklahoma will require hepatitis A (HepA) vaccination for all children entering kindergarten and seventh grade.
This decision is an attempt to end the three-year hepatitis A virus (HAV) outbreak in Oklahoma that began in July 1994; the incidence of HAV infections has more than quadrupled in the past 10 years, said Phyllis Brown, state immunization program coordinator, Oklahoma State Department of Health.
The state's cost for the vaccine and associated expenses is estimated at $498,000. The state legislature granted the program $600,000 for start-up costs; such as increasing vaccine storage, expanding staff and administrative costs, Brown said.
The HepA purchased with the nearly $500,000 provided each year will be used for children unable to receive the vaccine through private insurance, the Vaccines for Children fund or similar cost-free programs operating in the state.
Upon recognizing the epidemic, the state immediately instituted an active surveillance system and rapidly identified new cases. Immune globulin was given to close contacts of confirmed cases.
Michael Crutcher, MD, an Oklahoma state epidemiologist, acknowledged that the stage of the current outbreak is past vaccination and called the school-entry immunization requirement a long-term control of hepatitis A.
"Our plan to control hepatitis A is not so much aimed at this current outbreak; it's more starting to vaccinate for the purpose of building immunity and preventing this from occurring in the future," he said. "The effects of the vaccine aren't expected to be seen for several years."
The Oklahoma outbreak spread across the state with large numbers of children affected, but the highest rates have been in the 20- to 40-year age group; only about 13% of total cases have been in children younger than 9 years. However, children who attend child care centers are at an increased risk for HAV infection.
A great effort by the public health system was also launched to target high-risk groups, including drug users, to teach them about transmission and the importance of hygiene. Despite this effort, little impact was observed.
"Undoubtedly, we prevented some people from getting hepatitis A, but we certainly did not `nip this in the bud' by any means," Crutcher said.
The rates have begun to decline and by the end of the year the state should be back down to 10-15 cases per 100,000 people.
The normal rate for endemic periods in the United States is 10-11 cases per 100,000 people. In Oklahoma during 1995, the rate reached 45 per 100,000. The epidemic peaked in 1996 with a rate of 81 per 100,000.
Oklahoma is not the only state which is facing increasing numbers of HAV cases. Arizona, California, Missouri, New Mexico, Oregon, Tennessee, Utah and Washington have also had similar problems with HepA, Crutcher said.
"The reasons aren't new or unusual - simply a normal cycle of disease," he added. "Once hepatitis A is established in a community, it is extremely difficult to stop, even with extensive public health resources focused on it."
As with any infectious disease, periodic cycling occurs. This is thought to be due to changing immunity levels of the population.
In many areas, a strong association with drug use is one possible reason for an increase in cases. Of the patients questioned, 21% said they had either been in contact with a drug user or used drugs themselves.
"In Oklahoma, we may have had the outbreak without that factor," Crutcher said.
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