摘要：Objectives. We assessed the effect on trends in hepatitis A incidence of the 1996 recommendation for routine hepatitis A vaccination of American Indian/Alaska Native (AIAN) children. Methods. We examined trends in hepatitis A incidence among AIAN peoples during 1990–2001 and vaccination coverage levels among children on the largest American Indian reservation. Results. Hepatitis A rates among AIANs declined 20-fold during 1997–2001. Declines in hepatitis A incidence occurred among AIANs in reservation and metropolitan areas. Among 1956 children living on the Navajo Nation whose medical records were reviewed, 1508 (77.1%) had received at least one dose of hepatitis A vaccine, and 1020 (52.1%) had completed the vaccine series. Conclusions. Hepatitis A rates among AIAN peoples have declined dramatically coincident with implementation of routine hepatitis A vaccination of AIAN children. Historically, hepatitis A incidence has been substantially higher among American Indians and Alaska Natives (AIANs) than in other racial/ethnic groups in the United States. 1 In the 1980s, the lifetime risk of hepatitis A virus (HAV) infection among AIANs living on reservations and in Alaskan villages approached 90%. 2, 3 Reported cases of hepatitis A among AIAN peoples during 1990–1995 accounted for 5.0%–8.7% of all US cases, although AIANs constituted only 0.86% of the total US population. The high rates of hepatitis A among AIAN peoples were largely the result of periodic, communitywide epidemics on reservations and in rural Alaskan communities. During a 1992–1993 outbreak in 25 rural Alaskan villages, the peak reported incidence of hepatitis A exceeded 2000 cases per 100 000 inhabitants in a 12-month period. 4 Similar rates have been documented during epidemics among AI populations living on reservations. 2 Although the epidemiology of hepatitis A among AIANs living in urban areas has not been as well characterized, disease rates consistently have been severalfold higher than rates among persons of other races/ethnicities living in the same areas. 5 Hepatitis A vaccine was licensed in the United States in 1995 and was first provided to AIAN children in a pilot program implemented by the Indian Health Service (IHS) on several Northern Plains Indian reservations during 1995–1996. 6 In December 1996, the Advisory Committee on Immunization Practices (ACIP) recommended routine vaccination of children in populations with high rates of hepatitis A, including AIAN children. 7 The vaccine became available free of charge to IHS healthcare facilities, after publication of the ACIP recommendations and the parallel Vaccines for Children (VFC) resolution, through VFC funding to state health departments. To assess the effect of the ACIP recommendation on hepatitis A incidence among AIAN peoples, we analyzed national surveillance data to characterize trends in disease incidence in counties with large AIAN populations before and after the implementation of routine hepatitis A vaccination of AIAN children, and we assessed vaccination coverage among children living on the largest American Indian reservation.
