[Skip to Content]
Access to paid content on this site is currently suspended due to excessive activity being detected from your IP address 54.163.129.96. Please contact the publisher to request reinstatement.
Sign In
Individual Sign In
Create an Account
Institutional Sign In
OpenAthens Shibboleth
[Skip to Content Landing]
Download PDF
Figure 1. Hepatitis A Vaccination Coverage Among Children by Year in Butte County, California, 1995-2000
Image description not available.
Age groups varied by year: 1995 includes 2- to 12-year-olds; 1996 includes 2- to 13-year-olds; 1997 includes 2- to 14-year-olds; 1998 includes 2- to 15-year-olds; 1999 includes 2- to 16-year-olds; and 2000 includes 2- to 17-year-olds.
Figure 2. Reported Hepatitis A Cases in Butte County, California, 1980-2000 (n = 1558)
Image description not available.
Figure 3. Average Annual Age-Specific Hepatitis A Incidence in Butte County, California, 1990-1994 and 1995-2000
Image description not available.
Figure 4. Hepatitis A Annual Incidence in Butte County, California, and All of California, 1990-2000
Image description not available.
Figure 5. Average Annual Hepatitis A Incidence by Age Group for Butte County, California, and All of California, 1990-1994 and 1995-2000
Image description not available.
1.
Centers for Disease Control and Prevention.  Communitywide outbreaks of hepatitis A.  Hepatitis Surveillance Rep.1987;51:6-8.
2.
Craig AS, Sockwell DC, Schaffner W.  et al.  Use of hepatitis A vaccine in a community-wide outbreak of hepatitis A.  Clin Infect Dis.1998;27:531-535.
3.
Shaw FE, Sudman JH, Smith SM.  et al.  A community-wide epidemic of hepatitis A in Ohio.  Am J Epidemiol.1986;123:1057-1065.
4.
Bell BP, Shapiro CN, Alter MJ.  et al.  The diverse patterns of hepatitis A epidemiology in the United States: implications for vaccination strategies.  J Infect Dis.1998;178:1579-1584.
5.
Centers for Disease Control and Prevention.  Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP).  MMWR Morb Mortal Wkly Rep.1999;48(RR-12):1-37.
6.
Centers for Disease Control and Prevention.  Hepatitis SurveillanceAtlanta, Ga: Centers for Disease Control and Prevention; 1996:16-18.
7.
Sagliocca L, Mele A, Gill ON.  et al.  A village outbreak of hepatitis A: acquaintance network and inapparent pre-school transmission compared.  Eur J Epidemiol.1988;4:470-472.
8.
Shaw FE, Shapiro CN, Welty TK.  et al.  Hepatitis transmission among the Sioux Indians of South Dakota.  Am J Public Health.1990;80:1091-1094.
9.
Greco D, De Giacomi G, Piersante GP.  et al.  A person to person hepatitis A outbreak.  Int J Epidemiol.1986;15:108-111.
10.
Staes CJ, Schlenker T, Risk I.  et al.  Sources of infection among persons with acute hepatitis A and no identified risk factors during a sustained communitywide outbreak.  Pediatrics.2000;106:e54.
11.
Yang N-Y, Yu P-H, Mao Z-X.  et al.  Inapparent infection of hepatitis A virus.  Am J Epidemiol.1988;127:599-604.
12.
Alaska Department of Health and Social Services.  Hepatitis A: continuing rural spread.  State Alaska Epidemiol Bull.1993;No. 18.
13.
Centers for Disease Control and Prevention.  Protection against viral hepatitis: recommendations of the Immunization Practices Advisory Committee (ACIP).  MMWR Morb Mortal Wkly Rep.1990;39(RR-2):1-27.
14.
Mann JM, Francis DP, Hoffman RE.  et al.  Assessment of immunoglobulin use for hepatitis A control in New Mexico.  Public Health Rep.1982;97:516-520.
15.
Pavia AT, Nielsen L, Armington L.  et al.  A community-wide outbreak of hepatitis A in a religious community: impact of mass administration of immune globulin.  Am J Epidemiol.1990;131:1085-1093.
16.
Gilden B, Makintubee S, Istre GR. Community-wide outbreak of hepatitis A among an Indian population in Oklahoma.  South Med J.1992;85:9-13.
17.
Majeed FA, Stuart JM, Cartwright KAV.  et al.  An outbreak of hepatitis A in Gloucester, UK.  Epidemiol Infect.1992;109:167-173.
18.
Innis B, Snitbhan R, Kunasol P.  et al.  Protection against hepatitis A by an inactivated vaccine.  JAMA.1994;271:1328-1334.
19.
Werzberger A, Mensch B, Kuter B.  et al.  A controlled trial of a formalin-inactivated hepatitis A vaccine in healthy children.  N Engl J Med.1992;327:453-457.
20.
Nalin D, Kuter B, Brown L.  et al.  Worldwide experience with the CR326F-derived inactivated hepatitis A virus vaccine in pediatric and adult populations: an overview.  J Hepatol.1993;18(suppl 2):S51-S55.
21.
Andre FE, D'Hondt E, Delem A.  et al.  Clinical assessment of the safety and efficacy of an inactivated hepatitis A vaccine: rationale and summary of findings.  Vaccine.1992;10(suppl 1):S160-S168.
22.
McMahon BJ, Beller M, Williams J.  et al.  A program to control hepatitis A in Alaska by using an inactivated hepatitis A vaccine.  Arch Pediatr Adolesc Med.1996;150:733-739.
23.
Centers for Disease Control and Prevention.  Hepatitis A vaccination programs in communities with high rates of hepatitis A.  MMWR Morb Mortal Wkly Rep.1997;46:600-603.
24.
Centers for Disease Control and Prevention.  Summary of notifiable diseases, United States, 1999.  MMWR Morb Mortal Wkly Rep.1999;48:1-104.
25.
Centers for Disease Control and Prevention.  Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP).  MMWR Morb Mortal Wkly Rep.1996;45(RR-15):1-30.
26.
Van Beneden C, Hedberg K, Zimmerman P.  et al.  Epidemic hepatitis A among illicit drug users in Oregon: evidence for adult-to-adult transmission. Paper presented at: International Conference on Emerging Infectious Diseases Meeting; March 8-11, 1998; Atlanta, Ga.
Original Contribution
December 19, 2001

Control of Hepatitis A Through Routine Vaccination of Children

Author Affiliations

Author Affiliations: National Immunization Program (Drs Averhoff and Ms Deladisma) and Division of Viral Hepatitis, National Center for Infectious Diseases (Drs Shapiro, Bell, and Margolis and Mr Simard), Centers for Disease Control and Prevention, Atlanta, Ga; Butte County Department of Public Health, Oroville, Calif (Drs Ward and Lundberg and Ms Hyams); California Department of Health Services, Immunization Branch, Berkeley (Mr Burd and Dr Smith); and Merck Vaccine Division (Dr Nalin) and Merck Research Laboratories (Dr Kuter), West Point, Pa.

JAMA. 2001;286(23):2968-2973. doi:10.1001/jama.286.23.2968
Context

Context The impact of routine hepatitis A vaccination of children living in large communities with elevated disease rates has not been evaluated.

Objective To determine the effect of routine vaccination of children on disease incidence in a community with recurrent hepatitis A epidemics.

Design, Setting, and Participants Community-based demonstration project conducted from January 12, 1995, through December 31, 2000, in Butte County, California, among children aged 2 to 17 years.

Intervention In 1995, vaccination was offered to children aged 2 to 12 years during vaccination clinics conducted on 2 occasions 6 to 12 months apart at most schools in the county. In 1996-2000, vaccine was distributed to community health care clinicians, who vaccinated eligible children without charge. Vaccine was also available at health department clinics, selected child care centers, and other sites.

Main Outcome Measures Hepatitis A vaccination coverage, hepatitis A incidence, and vaccine effectiveness.

Results During the study period, 29 789 (66.2%) of an estimated 44 982 eligible children received at least 1 vaccine dose; 17 681 (39.3%) received a second dose. The number of hepatitis A cases among the entire county population declined 93.5% during the study period, from 57 cases in 1995 to 4 in 2000, the lowest number of cases reported in the county since hepatitis A surveillance began in 1966. The 2000 incidence rate of 1.9 per 100 000 population was the lowest of any county in the state. Of the 245 cases reported during the 6-year period, 40 (16.3%) occurred among children 17 years of age or younger, of which 16 (40%) occurred in 1995 and only 1 in 2000. One of the 27 case patients eligible for vaccination had been vaccinated, having received the first dose 3 days before symptom onset. The estimated protective vaccine efficacy was 98% (95% confidence interval, 86%-100%).

Conclusions In this population, hepatitis A vaccine was highly effective in preventing disease among recipients. Childhood vaccination appears to have decreased hepatitis A incidence among children and adults and controlled the disease in a community with recurrent epidemics.

Hepatitis A continues to be one of the most frequently reported vaccine-preventable diseases in the United States. Hepatitis A incidence displays a cyclic pattern, and most disease occurs in the context of community-wide outbreaks during which a large proportion of patients do not have a recognized risk factor.16 Available data suggest that young children, frequently asymptomatic when infected, play an important role in hepatitis A virus (HAV) transmission.712 Until recently, immunoglobulin and improved hygiene were the only measures available to prevent and control hepatitis A.13 Although immunoglobulin has been shown to be effective in preventing hepatitis A among persons with a recognized exposure, it has limited effectiveness in controlling the spread of HAV infection in the community because many people are unaware of their exposure.3,1417

Hepatitis A vaccines, available in the United States since 1995, are highly effective in preventing disease among immunized persons.1821 Routine vaccination of children living in small communities that had experienced recurrent hepatitis A epidemics and in which most adults are immune has been shown to be effective in helping to interrupt disease transmission.22,23 However, the impact of routine childhood vaccination on disease incidence in large communities that experience recurrent epidemics, where most of the population is thought to be susceptible to the disease, has not been determined.5 We report the results of routine hepatitis A vaccination of children in one such community.

METHODS

Butte County, with an estimated year 2000 population of 207 158, is located in the San Joaquin Valley of California. During an outbreak of hepatitis A from 1985 to 1988, 495 cases (average annual incidence, 112.7 per 100 000 population) were reported, and between 1988 and 1992, the incidence fluctuated between 20 and 45 per 100 000 population. The number of reported cases increased to 128 (65.2 per 100 000 population) in 1993 and then to 230 (117.3 per 100 000 population) in 1994. The 1994 rate was highest among children younger than 15 years (193.0 per 100 000 population).

From January 12, 1995, through December 31, 2000, hepatitis A vaccine was offered free of charge to children residing in the county by means of a demonstration project conducted in 2 phases. In 1995, the project focused primarily on controlling the ongoing outbreak by vaccination of children under an investigational new drug (IND) protocol before the vaccine was licensed by the US Food and Drug Administration (FDA). From 1996 through 2000, following FDA licensure of the vaccine, the project evaluated the effectiveness of routine vaccination of children. The study was approved by the institutional review board of the Centers for Disease Control and Prevention (CDC) and the Butte County Board of Supervisors.

Target Population

During the first phase, in 1995, vaccination was recommended and made available to children aged 2 to 12 years. The vaccine was offered to eligible children during vaccination clinics conducted on 2 occasions 6 to 12 months apart at most schools in the county. School-aged children up to 12 years (or in the seventh grade) were encouraged to receive the vaccine during the school vaccination clinics. Preschool-aged children also could be vaccinated at the school clinics. In addition, vaccine was offered to all eligible children aged 2 to 12 years at routine vaccination clinics conducted at Butte County Health Department (BCHD) sites.

Each child was given a vaccine adverse event report card, thermometer, and instructions for parents on how to record temperature and adverse events. Parents were asked to return the cards to the school or health department and to report serious adverse events to the health department immediately by telephone.

The second phase of the study, 1996-2000, focused on establishment of sustained childhood hepatitis A vaccination in the county through community health care practitioners. Vaccine was distributed to clinicians who agreed to vaccinate eligible children in their practice without charge and provide information on each vaccinated child to a registry maintained by the BCHD. Vaccine was also made available at health department clinics, selected child care centers, and other sites, such as the Department of Agriculture's Special Supplemental Program for Women, Infants, and Children (WIC) clinics. The target population increased annually to include those additional birth cohorts of children who had reached their second birthday and children who were older than 12 years. By the end of the study, children aged 2 to 17 years were eligible to receive vaccine and were included in the analysis.

The vaccination registry maintained by the BCHD recorded date and place of vaccination, demographic data, and adverse events. First- and second-dose vaccination coverage was calculated using registry data and population estimates. Population estimates, including race and ethnicity, were obtained from the State of California, Department of Finance, Demographic Research Unit. The estimated number of unvaccinated children was determined by subtracting the number of children vaccinated (from the registry) from the estimated population. These estimates were also used for calculating vaccine effectiveness.

Hepatitis A Vaccine

Inactivated hepatitis A vaccine (VAQTA, Merck & Co Inc, West Point, Pa) was administered as the pediatric formulation (25 U, approximately 25 ng of purified viral protein in 0.5-mL volume) on a 2-dose (0- and 6- to 12-month) schedule. Because the first phase of the study was conducted under an IND protocol, the written consent reflected that the vaccine had not been licensed by the FDA. When the vaccine was licensed in 1996, a standard, simplified consent form, similar to the vaccine information statement recommended by the CDC, was used. The vaccine is licensed for persons aged 2 years or older.

Hepatitis A Surveillance

Although hepatitis A reporting is required by California law, enhanced surveillance was established in the county in 1995, coincident with implementation of the vaccination program. Reporting was stimulated in sites most likely to encounter cases and included weekly contact with emergency department and walk-in clinic staff to ascertain the number of suspected cases or serologic test results indicative of hepatitis A. In addition, laboratories that conducted diagnostic testing for hepatitis A were contacted and asked to report all positive test results that originated from Butte County. Surveillance was further stimulated by mailing letters to primary care practitioners (including pediatricians, family physicians, and general practitioners) that encouraged reporting of suspected cases. In addition, information about the study was presented at regularly scheduled continuing education meetings for physicians and nurses.

A case patient was defined as a patient with a positive serologic test result for IgM antibody to HAV (anti-HAV) or the clinical diagnosis of hepatitis A without serologic confirmation. All suspected case patients were interviewed by a study nurse (I.H.). A detailed standard case investigation form, the Viral Hepatitis Surveillance Program form, was used to collect additional demographic and risk factor information on reported cases. Case patients were asked about receipt of hepatitis A vaccine, and the vaccination registry was also searched for verification of receipt of vaccine.

To assess the impact of the vaccination program, age-specific hepatitis A incidence in the county during the 6-year vaccination program was compared with the incidence during 1990-1994, before the program. The mean of the 5 or 6 annual rates, using the estimated population denominator for the relevant year for each rate, was calculated. In addition, statewide, age-specific hepatitis A incidence was compared with that in Butte County for 1990-1994 and 1995-2000, using surveillance data reported to the National Notifiable Diseases Surveillance System (NNDSS) of the CDC.24 The NNDSS data for 2000 are provisional.

Estimates of Vaccine Effectiveness

Vaccine effectiveness was estimated by comparing the incidence of reported hepatitis A among children who had received at least 1 dose of vaccine to the incidence among unvaccinated children of the same age. Vaccine effectiveness was calculated using the following formula: 1 − (observed attack rate in vaccine recipients/observed attack rate in unvaccinated children). The hepatitis A attack rate in vaccine recipients was calculated as follows: number of reported cases among vaccinated children (ie, receiving ≥1 dose of hepatitis A vaccine)/number of vaccinated children in the vaccine registry. The attack rate for unvaccinated children was calculated as follows: number of reported cases among unvaccinated children/estimated number of unvaccinated children in the target age group. Vaccine effectiveness estimates were based on number of children eligible at the end of the study period (ie, aged 2-17 years).

Statistical Analysis

Data were analyzed using Epi Info software, version 6.04b (CDC) and SAS statistical software, version 8e (SAS Institute Inc, Cary, NC). The Taylor series 95% confidence interval (CI) for the estimate of vaccine effectiveness was calculated.

RESULTS
Vaccination Coverage

From January 12, 1995, through December 31, 2000, of an estimated 44 982 children in the age groups eligible for hepatitis A vaccination, 29 789 (66.2%) received at least 1 dose of vaccine and 17 681 (39.3%) received 2 doses. First-dose vaccination coverage increased annually from 35.2% to 66.2%, and second dose coverage increased from 14.5% to 39.3% (Figure 1). Cumulative first dose vaccination coverage was similar among children aged 5 to 10 years (69.0%, 11 352/16 460) and 11 to 17 years (67.8%, 14 047/20 730) and lower among children aged 2 to 4 years (56.3%, 4390/7792).

The number and ages of children vaccinated varied during the 2 phases of the project. In 1995, when school-based vaccination was the primary strategy used, 10 754 (35.2%) of the 30 575 children aged 2 to 12 years received at least 1 dose of hepatitis A vaccine. Of these, 9805 (91.2%) were school-aged (>5 years), and 10 205 (94.8%) received their first dose of vaccine during school-based vaccination clinics. In 1996-2000 (the second phase of the program), an additional 19 035 children received 1 or more vaccine doses; of these, 10 668 (56.0%) were aged 5 years or older and 8367 (44.0%) were 2 to 4 years. After 1995, most children (14 484 [76%]) were vaccinated in clinical settings.

Disease Incidence

The average annual hepatitis A incidence in Butte County during the 5 years before the demonstration project (1990-1994) was 47.9 per 100 000 population (range, 122.5-11.8 per 100 000 population) and declined by 56.8% to 20.7 per 100 000 population (range, 48.7-0.97 per 100 000 population) during 1995-2000 (Figure 2). The age-specific incidence decreased among all age groups during 1995-2000 compared with that in 1990-1994, but the effect was most pronounced among the younger age groups (Figure 3). Incidence decreased 78.9% among children aged 17 years or younger (67.3 to 13.5 per 100 000 population) compared with 44.3% among persons older than 17 years (41.3 to 23.0 per 100 000 population).

Of the 245 cases reported to the BCHD between 1995 and 2000, 243 (99.2%) were serologically confirmed. Thirteen patients required hospitalization and 4 died (aged 39, 41, 56, and 79 years). During this period, the reported number of cases declined 93.5%, from 57 in 1995 to 4 in 2000 (Figure 2). Of the 40 (16.3%) cases that occurred among children 17 years or younger during 1995-2000, 16 (40%) occurred in 1995 and only 1 occurred in 2000.

During 1995-2000, 60.8% (n = 149; cumulative incidence, 147.3 per 100 000 population) of cases occurred among males. Non-Hispanic whites accounted for 87.3% (n = 214; cumulative incidence, 123.2 per 100 000 population) of the cases, whereas Native Americans (n = 15; cumulative incidence, 449.1 per 100 000 population), Hispanics (n = 10; cumulative incidence, 53.9 per 100 000 population), Asian and Pacific Islanders (n = 5; cumulative incidence, 60.8 per 100 000 population), and blacks (n = 1; cumulative incidence, 36.2 per 100 000 population) accounted for the remainder.

Recognized potential sources of infection reported by case patients included contact with a hepatitis A case (n = 89, 36.3%) and illegal drug use (n = 25, 10.2%). Antecedent international travel to a country with endemic hepatitis A (n = 9), association with child care (n = 7), homosexual activity (n = 5), and association with a common source outbreak of hepatitis A (n = 2) were each reported by less than 3% of case patients. For 108 case patients (44.1%), no risk factor could be identified. All 25 case patients who identified drug use as a risk factor were reported during 1996-1997.

During 1990-1997, annual hepatitis A incidence in Butte County was at least equal to, and up to 5.7 times higher, than the overall California rate (Figure 4). In 1998, the Butte County hepatitis A rate fell below the overall California rate and stayed lower through 2000. In 2000, the Butte County rate (1.9 per 100 000 population) was the lowest reported in any county in the state (data not shown). Compared with the previous 5 years, age-specific incidence during the study period declined 80% among children aged 17 years or younger in the county, compared with 21% in the state (Figure 5).

Vaccine Effectiveness

During the study period, 27 hepatitis A cases occurred among children eligible for the vaccination program, including 26 among the 15 193 unvaccinated children and 1 in a 12-year-old boy who had received his first dose of vaccine 3 days before onset of illness. The estimated protective efficacy of 1 or more doses of vaccine was 98% (95% CI, 86%-100%).

Adverse Reactions

No serious adverse events were reported among the 29 789 children who received 1 or more doses during the study period. Among the 5471 vaccine doses for which report cards were available (accounting for 30.6% of prelicensure vaccine doses administered), adverse reactions were reported on 1983 (36.2%), were generally described as mild, and included injection site reactions, fever, or rash.

COMMENT

This 6-year project demonstrated the feasibility and effectiveness of routine childhood hepatitis A vaccination and its impact on community-wide rates of disease. Hepatitis A incidence declined to historic lows following the introduction of hepatitis A vaccination, and since 1998, the number of reported cases has been lower than in any year since hepatitis A surveillance began in 1966. The decline appears to be sustained; only 2 cases were reported to the CDC during the first half of 2001 (CDC, unpublished data, 2001). Furthermore, the 2000 Butte County disease rate was the lowest of any county in California, suggesting that community-wide childhood vaccination was responsible for a sustained reduction in hepatitis A incidence in Butte County. Finally, no serious adverse events were reported among the nearly 30 000 vaccine recipients, supporting the safety of hepatitis A vaccination.

Although the overall purpose of the demonstration project was to evaluate whether childhood hepatitis A vaccination could be sustained, the purpose of the first phase was to evaluate whether rapid vaccination of multiple age cohorts could control the ongoing outbreak.25 However, the impact of the first phase is uncertain. As has been the experience in other large communities, the vaccination program in Butte County was not begun until well into the second year of the outbreak, when hepatitis A incidence may have already been waning.2,5 Other California counties with similar historical patterns of hepatitis A incidence and without vaccination programs also reported declines in incidence during this time. However, vaccination may have shortened the epidemic, which lasted 2 years compared with the previous 3-year epidemic. In addition, sustained community-wide vaccination may prevent future outbreaks, as has been observed in smaller communities.5,23

Before the demonstration project, children had the highest disease incidence in Butte County, and incidence declined to levels below that of adults following the implementation of the vaccination program. Of the cases that were reported during the vaccination program, including during the peak year of 1997, a substantial proportion occurred among adult users of illegal drugs; this appears to have mitigated the impact of childhood vaccination on overall disease incidence. Other studies have suggested that HAV transmission can be sustained among adult users of illegal drugs with little transmission to or from children.26 However, the long-term impact of vaccination of children and adolescents on transmission among adult drug users is unknown.

This study has some potential limitations. Because the incidence of hepatitis A varies from year to year, it is not possible to know what the incidence would have been without the vaccination program and we did not have the benefit of a "control" community. However, we compared hepatitis A incidence in Butte County to that in the rest of California and also before and after implementation of the vaccination program, with Butte County serving as its own control. Both analyses suggested the effectiveness of the vaccination program.

Alternative explanations for the observed decline in hepatitis A incidence could be postulated. "Surveillance fatigue" could have occurred if cases continued to occur but were not reported to the surveillance system. However, hepatitis A reporting did not begin with the advent of the vaccination program but has been ongoing in Butte County and the rest of the state for more than 20 years. Although it is possible that the initial enthusiasm for the enhanced surveillance implemented during the program waned, it is extremely unlikely that passive routine surveillance would be affected. Furthermore, physicians were not the only source of reports; positive reports were also received from laboratories. Depletion of the pool of susceptible persons in the population would also lead to a decline in incidence. However, although the age-specific prevalence of immunity in Butte County is unknown, serologic surveys indicate that most of the US population remains susceptible to HAV infection.5 Although reasons for the spontaneous waning of community-wide outbreaks are not well understood, taking into consideration the relatively low baseline prevalence of immunity and the number of cases typically reported during outbreaks, a considerable proportion of the population remains susceptible to HAV infection even after outbreaks.

We calculated vaccine effectiveness in preventing symptomatic, clinically recognizable hepatitis A, not asymptomatic HAV infection. This allows for comparison between our results and those of published efficacy studies.18,19 We did not verify the vaccination status of children not listed in the vaccination registry. However, because of the widespread availability of the study vaccine, we believe that very few, if any, children in Butte County received hepatitis A vaccine outside the study.

Childhood hepatitis A vaccination in Butte County posed some unique challenges, including the lack of a routinely scheduled immunization visit for children aged 2 years or older and the need to initially administer vaccine under an IND protocol, which necessitated more involved consent procedures. School-based vaccination clinics were used at the outset as the primary vaccination sites and achieved only modest vaccination coverage rates in schoolchildren and low rates in preschool children. When clinician-based vaccination was introduced as the primary vaccination strategy for all children following vaccine licensure, vaccination coverage increased, indicating that it is possible to achieve fairly high levels of hepatitis A vaccination coverage among children.

To our knowledge, no other community of this size in the United States has delivered hepatitis A vaccine to such a large proportion of its children and sustained a vaccination program for 6 years. The Butte County experience suggests that, over time, routine vaccination of children can reduce overall disease rates in the community. This previews the potential impact of routine childhood hepatitis A vaccination, as recently recommended by the Advisory Committee on Immunization Practices for areas of the United States with consistently high hepatitis A infection rates.5

References
1.
Centers for Disease Control and Prevention.  Communitywide outbreaks of hepatitis A.  Hepatitis Surveillance Rep.1987;51:6-8.
2.
Craig AS, Sockwell DC, Schaffner W.  et al.  Use of hepatitis A vaccine in a community-wide outbreak of hepatitis A.  Clin Infect Dis.1998;27:531-535.
3.
Shaw FE, Sudman JH, Smith SM.  et al.  A community-wide epidemic of hepatitis A in Ohio.  Am J Epidemiol.1986;123:1057-1065.
4.
Bell BP, Shapiro CN, Alter MJ.  et al.  The diverse patterns of hepatitis A epidemiology in the United States: implications for vaccination strategies.  J Infect Dis.1998;178:1579-1584.
5.
Centers for Disease Control and Prevention.  Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP).  MMWR Morb Mortal Wkly Rep.1999;48(RR-12):1-37.
6.
Centers for Disease Control and Prevention.  Hepatitis SurveillanceAtlanta, Ga: Centers for Disease Control and Prevention; 1996:16-18.
7.
Sagliocca L, Mele A, Gill ON.  et al.  A village outbreak of hepatitis A: acquaintance network and inapparent pre-school transmission compared.  Eur J Epidemiol.1988;4:470-472.
8.
Shaw FE, Shapiro CN, Welty TK.  et al.  Hepatitis transmission among the Sioux Indians of South Dakota.  Am J Public Health.1990;80:1091-1094.
9.
Greco D, De Giacomi G, Piersante GP.  et al.  A person to person hepatitis A outbreak.  Int J Epidemiol.1986;15:108-111.
10.
Staes CJ, Schlenker T, Risk I.  et al.  Sources of infection among persons with acute hepatitis A and no identified risk factors during a sustained communitywide outbreak.  Pediatrics.2000;106:e54.
11.
Yang N-Y, Yu P-H, Mao Z-X.  et al.  Inapparent infection of hepatitis A virus.  Am J Epidemiol.1988;127:599-604.
12.
Alaska Department of Health and Social Services.  Hepatitis A: continuing rural spread.  State Alaska Epidemiol Bull.1993;No. 18.
13.
Centers for Disease Control and Prevention.  Protection against viral hepatitis: recommendations of the Immunization Practices Advisory Committee (ACIP).  MMWR Morb Mortal Wkly Rep.1990;39(RR-2):1-27.
14.
Mann JM, Francis DP, Hoffman RE.  et al.  Assessment of immunoglobulin use for hepatitis A control in New Mexico.  Public Health Rep.1982;97:516-520.
15.
Pavia AT, Nielsen L, Armington L.  et al.  A community-wide outbreak of hepatitis A in a religious community: impact of mass administration of immune globulin.  Am J Epidemiol.1990;131:1085-1093.
16.
Gilden B, Makintubee S, Istre GR. Community-wide outbreak of hepatitis A among an Indian population in Oklahoma.  South Med J.1992;85:9-13.
17.
Majeed FA, Stuart JM, Cartwright KAV.  et al.  An outbreak of hepatitis A in Gloucester, UK.  Epidemiol Infect.1992;109:167-173.
18.
Innis B, Snitbhan R, Kunasol P.  et al.  Protection against hepatitis A by an inactivated vaccine.  JAMA.1994;271:1328-1334.
19.
Werzberger A, Mensch B, Kuter B.  et al.  A controlled trial of a formalin-inactivated hepatitis A vaccine in healthy children.  N Engl J Med.1992;327:453-457.
20.
Nalin D, Kuter B, Brown L.  et al.  Worldwide experience with the CR326F-derived inactivated hepatitis A virus vaccine in pediatric and adult populations: an overview.  J Hepatol.1993;18(suppl 2):S51-S55.
21.
Andre FE, D'Hondt E, Delem A.  et al.  Clinical assessment of the safety and efficacy of an inactivated hepatitis A vaccine: rationale and summary of findings.  Vaccine.1992;10(suppl 1):S160-S168.
22.
McMahon BJ, Beller M, Williams J.  et al.  A program to control hepatitis A in Alaska by using an inactivated hepatitis A vaccine.  Arch Pediatr Adolesc Med.1996;150:733-739.
23.
Centers for Disease Control and Prevention.  Hepatitis A vaccination programs in communities with high rates of hepatitis A.  MMWR Morb Mortal Wkly Rep.1997;46:600-603.
24.
Centers for Disease Control and Prevention.  Summary of notifiable diseases, United States, 1999.  MMWR Morb Mortal Wkly Rep.1999;48:1-104.
25.
Centers for Disease Control and Prevention.  Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP).  MMWR Morb Mortal Wkly Rep.1996;45(RR-15):1-30.
26.
Van Beneden C, Hedberg K, Zimmerman P.  et al.  Epidemic hepatitis A among illicit drug users in Oregon: evidence for adult-to-adult transmission. Paper presented at: International Conference on Emerging Infectious Diseases Meeting; March 8-11, 1998; Atlanta, Ga.
×