PEDIATRICS Vol. 117 No. 1 January 2006, pp. 30-33 (doi:10.1542/peds.2005-0286)
ARTICLE |
Factors Associated With Hepatitis A Vaccination Among Children 24 to 35 Months of Age: United States, 2003
a Epidemic Intelligence Service, Epidemiology Program Office
b Division of Viral Hepatitis, National Center for Infectious Diseases
c National Immunization Program, Centers for Disease Control and Prevention, Atlanta, Georgia
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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OBJECTIVES. In 1999, the Advisory Committee on Immunization Practices made recommendations for hepatitis A vaccination of children according to historic rates of hepatitis A incidence in different regions of the country. The objective of this study was to examine hepatitis A vaccination coverage rates among children living in states with different vaccination recommendations and to examine individual characteristics associated with vaccination.
METHODS. Hepatitis A vaccination status data were collected for children 24 to 35 months of age through the National Immunization Survey, a telephone survey with health care provider-verified vaccination results. Vaccination status data were collected from children in each of the 50 states and 28 selected urban areas.
RESULTS. In 2003, 50.9% (95% confidence interval [CI]: 47.6–54.2%) of children living in 11 states where routine hepatitis A vaccination is recommended had received 
1 dose, compared with 25.0% (95% CI: 21.8–28.2%) of children in 6 states where vaccination is suggested and 1.4% (95% CI: 1.0–1.8%) of children in 33 states without a recommendation. Coverage was higher among children who lived in urban areas, were Hispanic or American Indian/Alaska Native, or were born to women with less education.
CONCLUSIONS. Hepatitis A vaccination is being targeted successfully to children at higher risk of infection; however, overall vaccination coverage remains lower for hepatitis A vaccination, compared with other routine childhood vaccinations.
Key Words: hepatitis A • vaccination coverage • children • race/ethnicity • immunization policy
Abbreviations: ACIP—Advisory Committee on Immunization Practices • AIAN—American Indian/Alaska Native • CI—confidence interval • NIS—National Immunization Survey • OR—odds ratio
Hepatitis A incidence rates in the United States have historically differed according to race and ethnicity, socioeconomic status, and region of the country, with rates being highest among American Indian/Alaska Native (AIAN) and Hispanic children, children of lower socioeconomic status, and children in the western United States. In 1996, the Advisory Committee on Immunization Practices (ACIP) published recommendations for hepatitis A vaccination targeting children at highest risk of infection, such as AIAN children and children living in communities with high rates of hepatitis A infection.1 In 1999, routine vaccination was recommended for all children (24 months of age) living in 11 states where average annual hepatitis A incidence rates (during a 10-year baseline period of 1987–1997) were at least 20 cases per 100000 population (twice the national average). The ACIP also indicated that routine vaccination should be considered for children living in 6 states where average annual incidence rates were 10 to 20 cases per 100000 population.2 Routine statewide vaccination was not recommended for children living in the other 33 states, where rates were below the national average.
In 2003, the first national hepatitis A vaccination coverage data for children 24 to 35 months of age were collected. These data were used to examine geographic and racial/ethnic variations in hepatitis A vaccination coverage.3 The current brief report summarizes this information and presents additional factors that were identified as being associated with vaccination.
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METHODS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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The National Immunization Survey (NIS) provides annual estimates of vaccination coverage among children 19 to 35 months of age for each of the 50 states and 28 selected urban areas. In 2003, the NIS collected data on hepatitis A vaccination coverage for the first time. Hepatitis A vaccination coverage information was limited to children 24 to 35 months of age and was calculated for
1 vaccine dose. To collect vaccination information, NIS uses a quarterly random-digit-dialing telephone survey for each area and determines vaccination status from health care provider records. The telephone survey is designed to identify households with eligible children 19 to 35 months of age. Sampling weights are used to account for refusal and nonresponse (at multiple levels, eg, in determining residential households and households with eligible children, and to adjust for incomplete interviews) and the probability of a household having >1 telephone line. Data are weighted to adjust for households lacking telephone service by using data from the National Health Interview Survey, which collects national vaccination data from both telephone-containing and non–telephone-containing households, and the Current Population Survey, which provides geographic data on telephone coverage. Weights are also adjusted for provider nonresponse in the second phase of the survey, when, with consent from the parent/guardian, the child’s vaccination providers are mailed an immunization history questionnaire. More detailed methods are presented elsewhere.4,5
Logistic-regression analysis was conducted with weighted data, by using variables for vaccination policy area (routine vaccination recommendation of "recommended," "consider," or "no recommendation"), race/ethnicity, mother’s age, mother’s education, mother’s marital status, number of health care providers, provider type, urbanicity (urban, suburban, or rural residence, based on metropolitan statistical area designation), poverty level, and number of children in the household, as well as interactions between variables. Variables were eliminated by using backward elimination, to determine a final model. Human subject review and approval were provided by the Centers for Disease Control and Prevention Institutional Review Board (review 2000–17).
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Hepatitis A vaccination records were obtained from health care providers for 13731 (68.7%) of 19979 eligible children identified in telephone interviews. The average unweighted sample size for the 50 states and the District of Columbia was 269 children (range: 152–920 children).
Among children living in the 11 states where routine hepatitis A vaccination is recommended, 50.9% (95% confidence interval [CI]: 47.6–54.2%; range among states: 6.4–72.7%) had received 1 hepatitis A vaccine dose (Fig 1). Among children living in the 6 states where routine hepatitis A vaccination should be considered, 25.0% (95% CI: 21.8–28.2%; range among states: 0.6–32.3%) had received 1 hepatitis A vaccine dose (Fig 1). Among children living in the 33 states without a specific recommendation, 1.4% (95% CI: 1.0–1.8%; range among states: 0.0–4.3%) had received 1 hepatitis A vaccine dose (Fig 1).
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Factors found to be significantly associated with hepatitis A vaccination in a logistic-regression model included Hispanic (odds ratio [OR]: 1.99; 95% CI: 1.56–2.54) or AIAN (OR: 2.52; 95% CI: 1.48–4.28) race/ethnicity and having a mother with less than a high school education (OR: 1.41; 95% CI: 1.05–1.90), compared with reference groups (Table 1). Vaccination policy was found to modify the effect of urbanicity in the model, and results are therefore presented together. Residents of states where hepatitis A vaccination is recommended (for individuals in urban [metropolitan statistical area, central city] areas: OR: 46.45; 95% CI: 32.31–66.71; for individuals in periurban [metropolitan statistical area, non-central city] areas: OR: 37.35; 95% CI: 7.10–190.59; for individuals in rural [non-metropolitan statistical area] areas: OR: 23.36; 95% CI: 2.09–202.63) or should be considered (for individuals in urban areas: OR: 19.55; 95% CI: 13.68–27.92; for individuals in periurban areas: OR: 9.95; 95% CI: 1.82–53.82) were significantly more likely to be vaccinated, compared with urban residents of states with no hepatitis A vaccination recommendation (Table 1). Among individuals living in states with no hepatitis A vaccination recommendation, urban residents were 16.67 times more likely to be vaccinated than rural residents. In contrast, in areas where hepatitis A vaccination is recommended, urban residents were only 1.99 times more likely than rural residents to be vaccinated (Table 1).
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Hepatitis A vaccination coverage rates among children 24 to 35 months of age are significantly higher in states and among racial/ethnic groups that have had the greatest hepatitis A burdens historically. Although studies of coverage for vaccines other than hepatitis A found higher rates of vaccination among non-Hispanic white individuals6 and among individuals with higher socioeconomic status and native English language,7 apparently hepatitis A vaccination programs have had initial success in focusing vaccination efforts on children in geographic areas and among ethnic and racial groups at higher risk of hepatitis A infection.
The NIS does not collect data that can determine why hepatitis A vaccination rates vary among states with similar ACIP vaccination recommendations. The Vaccines for Children Fund provides reimbursement for vaccination of uninsured or underinsured children in states where vaccination is recommended or should be considered, but responsibility for implementation of ACIP recommendations rests with the states. Available data suggest that the manner and degree of implementation of these recommendations vary considerably.8 School entry requirements represent one strategy implemented, and states that had school entry requirements for hepatitis A vaccination had higher coverage rates in the 2003 NIS. For example, among states where the ACIP has suggested that hepatitis A vaccination be considered, the highest coverage rate was observed in Texas, where hepatitis A vaccination requirements for schoolchildren and children attending child care in Texas-Mexico border counties have been enacted. Similarly, among the 3 states with the highest levels of hepatitis A vaccination, Alaska has had a statewide hepatitis A vaccination requirement for children attending child care and for schoolchildren since 2001; Maricopa County, Arizona, has mandated vaccination for child care entry since 1999, and Oklahoma has phased in hepatitis A vaccination requirements for children attending child care and for elementary school-aged children beginning in 1998.8 In contrast, California does not have any statewide school or day care hepatitis A vaccination requirements but has achieved coverage rates among 24- to 35-month-old children that are similar to those in Oklahoma.
Higher hepatitis A vaccination coverage among Hispanic and AIAN populations might reflect implementation of earlier ACIP recommendations, published in 1996, that called for routine vaccination of AIAN children, as well as children living in communities with the highest hepatitis A incidence rates,1 including many Hispanic communities. Therefore, vaccination programs in some of these communities have had more time to mature, compared with statewide programs begun in response to the 1999 ACIP recommendations. For example, the Indian Health Services has been providing vaccinations routinely to AIAN populations since 1996 and recently reported 77% coverage (1 dose) among 3- to 6-year-old children in the Navajo Nation.9
NIS data have a number of limitations. First, the NIS is a telephone survey; although statistical weights adjust for nonresponse and households without telephones, some bias might remain. Second, although the NIS relies on provider-verified vaccination histories, incomplete records or reporting could result in underestimates of coverage. Finally, estimates for states and specific populations might be less reliable than national estimates because of small sample sizes. However, because the NIS uses a standardized approach across survey areas and is conducted continuously, estimates of vaccination coverage are comparable across states and over time. The current data provide an important baseline against which to measure future changes in hepatitis A vaccination coverage levels.
The extent to which coverage among children 24 to 35 months of age reflects coverage in older age groups is not known. Vaccination coverage surveys that include provider verification, such as the NIS, are not conducted routinely for older children; without such surveys, monitoring the impact of hepatitis A vaccination recommendations on overall coverage at a national level will be difficult. However, the 2003 NIS data indicate clearly that hepatitis A vaccination coverage rates among young children vary significantly among states where ACIP recommendations indicate that hepatitis A vaccination should be recommended routinely or considered and rates remain well below rates for other childhood vaccinations.10
The ACIP hepatitis A vaccination recommendations made in 1996, and revised in 1999 to include statewide recommendations in specific states, were intended as initial steps toward reducing hepatitis A burdens in the United States. Innovative implementation strategies based on local considerations, such as epidemiologic analyses and feasibility, were encouraged. The wide variations in coverage levels among 24- to 35-month-old children across states are unsurprising, considering the diverse approaches taken by states and the fact that hepatitis A vaccination cannot be integrated into early childhood (<24 months of age) vaccination schedules. As indicated by the NIS coverage data, many children in this age group who live in states where vaccination is recommended or should be considered remain at risk for hepatitis A. Sustaining and improving on recent decreases in hepatitis A incidence will likely require increasing hepatitis A vaccination coverage in areas where it is currently recommended, as well as in the rest of the United States. Reassessing current recommendations and developing programs for increasing vaccination coverage for children should be considered.
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CONCLUSIONS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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In 2003, 50.9% of children living in 11 states where routine hepatitis A vaccination is recommended had received
1 dose, compared with 25.0% of children in 6 states where vaccination is suggested and 1.4% of children in 33 states without a recommendation. Coverage was higher among children who lived in urban areas, were Hispanic or AIAN, or were born to women with less education. Although hepatitis A vaccination has been targeted successfully to populations at greater risk of disease, overall vaccination rates are well below other childhood vaccination rates, and greater efforts should be made to ensure vaccination of all children who meet current ACIP guidelines.
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FOOTNOTES |
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Accepted Mar 30, 2005.
Address correspondence to Anthony E. Fiore, MD, MPH, Division of Viral Hepatitis, Centers for Disease Control and Prevention, 1600 Clifton Rd, Mailstop G37, Atlanta, GA 30333. E-mail: abf4{at}cdc.gov
The authors have indicated they have no financial relationships relevant to this article to disclose.
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REFERENCES |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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- 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 Recomm Rep. 1996;45(RR-15)
:1
–30
- 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 Recomm Rep. 1999;48(RR-12) :1 –37
- Centers for Disease Control and Prevention. Hepatitis A vaccination coverage among children aged 24–35 months: United States, 2003. MMWR Morb Mortal Wkly Rep. 2005;54 :141 –144
- Zell ER, Ezzati-Rice TM, Battaglia MP, Wright RA. National Immunization Survey: the methodology of a vaccination surveillance system. Public Health Rep. 2000;115 :65 –77
- Smith PJ, Battaglia MP, Huggins VJ, et al. Overview of the sampling design and statistical methods used in the National Immunization Survey. Am J Prev Med. 2001;20 :17 –24
- Chu SY, Barker LE, Smith PJ. Racial/ethnic disparities in preschool immunizations: United States, 1996–2001. Am J Public Health. 2004;94 :973 –977
- Seid M, Simmes DR, Linton LS, Leah CE, Edwards CC, Peddecord KM. Correlates of vaccination for hepatitis B among adolescents: results from a parent survey. Arch Pediatr Adolesc Med. 2001;155 :921 –926
- Immunization Action Coalition. Hepatitis A Vaccination Recommendations and Policies. St Paul, MN: Immunization Action Coalition; 2003. Available at: www.immunize.org/laws/hepa.htm. Accessed February 1, 2005
- Bialek SR, Thoroughman DA, Hu D, et al. Hepatitis A incidence and hepatitis A vaccination among American Indians and Alaska Natives, 1990–2001. Am J Public Health. 2004;94 :996 –1001
- Centers for Disease Control and Prevention. National, state, and urban area vaccination coverage among children aged 19–35 months: United States, 2003. MMWR Morb Mortal Wkly Rep. 2004;53 :658 –661
- 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 Recomm Rep. 1999;48(RR-12) :1 –37
PEDIATRICS (ISSN 1098-4275). ©2006 by the American Academy of Pediatrics
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