SAN FRANCISCO — The incidence of pediatric hepatitis A took a nosedive since the introduction of a vaccine, Annemarie Wasley, Sc.D., reported at the annual meeting of the Infectious Diseases Society of America.
Now Hispanic children account for an increasing proportion of cases.
The Advisory Committee on Immunization Practices recommended in 1997 that people at high risk of getting hepatitis A (such as international travelers) get vaccinated, and in 1999 recommended routine childhood immunizations against hepatitis A in 17 states with high levels of the disease. Dr. Wasley of the Centers for Disease Control and Prevention, Atlanta, and her associates compared data from the National Notifiable Disease Surveillance System for 2004 with average rates in the prevaccine period of 1990–1997.
The national incidence of hepatitis A declined by 82% to 1.9/100,000 children aged 0–18 years old. “It's now at the lowest rate we've seen in more than 40 years of surveillance of this disease,” she said.
Incidence rates declined by 90% in the 17 states with recommendations for routine vaccination, compared with a decline of 68% in nonroutine vaccination states. In the prevaccine period, cases in the nonroutine vaccination states accounted for 27% of pediatric hepatitis A cases, compared with 68% of cases in 2004.
“The data support an important role for the vaccine in reducing hepatitis A incidence” and suggest that recommendations to expand routine hepatitis A vaccinations nationwide would further reduce pediatric rates of the disease, Dr. Wasley said.
For the first time, the incidence of hepatitis A in children is as low as, or lower than, rates in adults, she added.
The average annual number of U.S. pediatric hepatitis A cases dropped from 9,996 in 1990–1997 to 1,497 in 2004. The incidence declined in all races and ethnic groups in states with routine vaccination recommendations. Hepatitis A remained eight times more common in Hispanic children than in non-Hispanics, even though the incidence in states with routine vaccination recommendations declined by 94% in Hispanics in 2004, compared with the prevaccine period. In the states without recommendations for routine vaccination, pediatric hepatitis A incidence decreased by only 46% in Hispanics, compared with a 78% decline in non-Hispanics.
In 2004, 70 of every 100,000 Hispanic children had hepatitis A, “the highest rate of any demographic” in the study, she said. Hepatitis A in Hispanics accounted for 42% of all pediatric cases of the disease in the prevaccine period and 54% of all cases in 2004. Among Hispanic children, two-thirds of cases are in nonroutine vaccination states.
Although Hispanics constituted 5% of hepatitis A cases in nonroutine vaccination states in 1990–1997, they now account for nearly a third of pediatric cases in those states.
International travel is an important risk factor for hepatitis A disease, especially in Hispanic children, she said.
The proportion of cases attributed to exposure during international travel has increased over time, so that travel is now the most common risk factor. The rate of cases due to household contact with an infected person held steady, and the proportion of cases attributed to exposure to the disease in a child day-care setting decreased.
In 2004, 34% of children with hepatitis A had engaged in international travel, compared with 6% in the prevaccine period. Among Hispanic children with hepatitis A, 43% had traveled internationally, compared with 5% of non-Hispanic children with the disease. Almost all of the trips (97%) were to Central and South America.
The results show great progress in preventing hepatitis A with the vaccine, and highlight the need to reduce higher rates among Hispanic children, she said. “Improved hepatitis A vaccination of Hispanic children nationwide is needed to reduce this disparity, Dr. Wasley said.