A pathway to developing and testing quality measures aimed at improving adult vaccination rates in the United States.

Despite recommendations for vaccinating adults and widespread availability of immunization services (e.g., pharmacy venues, workplace wellness clinics), vaccination rates in the United States remain low. The U.S. National Adult Immunization Plan identified the development of quality measures as a priority and key strategy to address low adult vaccination coverage rates. The use of quality measures can provide incentives for increased utilization of preventive services. To address the lack of adult immunization measures, the National Adult and Influenza Immunization Summit, a coalition of adult immunization partners led by the Immunization Action Coalition, Centers for Disease Control and Prevention, and National Vaccine Program Office, spearheaded efforts to (1) identify gaps and priorities in adult immunization quality performance measurement; (2) explore feasibility of data collection on adult immunizations through pilot testing and engaging stakeholders; and (3) develop and test quality measure specifications. This paper outlines the process by which a public-private partnership drove the development of two adult immunization performance measures-an adult immunization status measure for influenza, tetanus and diphtheria (Td) and/or tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap), herpes zoster and pneumococcal vaccines, and a prenatal immunization status measure for influenza and Tdap vaccinations in pregnant women. These measures have recently been added to the 2019 Healthcare Effectiveness Data and Information Set (HEDIS®), a widely used set of performance measures reportable by private health plans.

Promoting Adult Immunization Using Population-Based Data for a Composite Measure.

INTRODUCTION: A composite adult immunization status measure is currently under consideration for adoption into the Healthcare Effectiveness Data and Information Set. This paper complements the Healthcare Effectiveness Data and Information Set health plan-level measure testing efforts by examining use of survey-based self-reported vaccination data to assess composite adult immunization coverage and identify limitations to using survey data to measure progress. METHODS: The 2015 National Health Interview Survey data were used in 2017 to calculate estimates for a composite of selected vaccines routinely recommended for adults aged ≥19 years, overall and in three age groups: 19-59, 60-64, and ≥65 years for tetanus and diphtheria toxoids (Td); tetanus toxoid; reduced diphtheria toxoid; and tetanus, diphtheria, acellular pertussis vaccine (Tdap); and herpes zoster, pneumococcal, and influenza vaccines. RESULTS: Composite coverage for adults aged ≥19 years including receipt of Tdap in the past 10 years and influenza vaccination was 11.9%, ranging from 6.3% in adults aged 60-64 years to 13.7% in adults aged 19-59 years. Excluding influenza, composite coverage was 20.7%, ranging from 8.1% (adults aged 60-64 years) to 25.2% (adults aged 19-59 years). In a composite including any Td-containing vaccine in the past 10 years, coverage including influenza vaccination for adults aged ≥19 years was 23.4%, ranging from 12.6% (adults aged 60-64 years) to 25.7% (adults aged 19-59 years). Excluding influenza, composite coverage was 51.4%, ranging from 15.8% (adults aged 60-64 years) to 63.0% (adults aged 19-59 years). CONCLUSIONS: Survey-based vaccination data may under- or over-estimate coverage, but most adults require at least one additional vaccination by any metric. A composite measure provides a single focal point to promote adherence to standards of care.

Human Papillomavirus Vaccine Uptake: Increase for American Indian Adolescents, 2013-2015.

INTRODUCTION: Although Indian Health Service, tribally-operated, and urban Indian (I/T/U) healthcare facilities have higher human papillomavirus (HPV) vaccine series initiation and completion rates among adolescent patients aged 13-17 years than the general U.S. population, challenges remain. I/T/U facilities have lower coverage for HPV vaccine first dose compared with coverage for other adolescent vaccines, and HPV vaccine series completion rates are lower than initiation rates. Researchers aimed to assist I/T/U facilities in identifying interventions to increase HPV vaccination series initiation and completion rates. STUDY DESIGN: Best practice and intervention I/T/U healthcare facilities were identified based on baseline adolescent HPV vaccine coverage data. Healthcare professionals were interviewed about barriers and facilitators to HPV vaccination. Researchers used responses and evidence-based practices to identify and assist facilities in implementing interventions to increase adolescent HPV vaccine series initiation and completion. Coverage and interview data were collected from June 2013 to June 2015; data were analyzed in 2015. SETTING/PARTICIPANTS: I/T/U healthcare facilities located within five Indian Health Service regions. INTERVENTION: Interventions included analyzing and providing feedback on facility vaccine coverage data, educating providers about HPV vaccine, expanding access to HPV vaccine, and establishing or expanding reminder recall and education efforts. MAIN OUTCOME MEASURES: Impact of evidence-based strategies and best practices to support HPV vaccination. RESULTS: Mean baseline first dose coverage with HPV vaccine at best practice facilities was 78% compared with 46% at intervention facilities. Mean third dose coverage was 48% at best practice facilities versus 19% at intervention facilities. Intervention facilities implemented multiple low-cost, evidence-based strategies and best practices to increase vaccine coverage. At baseline, most facilities used electronic provider reminders, had standing orders in place for administering HPV vaccine, and administered tetanus, diphtheria, and acellular pertussis and HPV vaccines during the same visit. At intervention sites, mean coverage for HPV initiation and completion increased by 24% and 22%, respectively. CONCLUSIONS: A tailored multifaceted approach addressing vaccine delivery processes and patient and provider education may increase HPV vaccine coverage.

Causes and Disparities in Death Rates Among Urban American Indian and Alaska Native Populations, 1999-2009.

OBJECTIVES: To characterize the leading causes of death for the urban American Indian/Alaska Native (AI/AN) population and compare with urban White and rural AI/AN populations. METHODS: We linked Indian Health Service patient registration records with the National Death Index to reduce racial misclassification in death certificate data. We calculated age-adjusted urban AI/AN death rates for the period 1999-2009 and compared those with corresponding urban White and rural AI/AN death rates. RESULTS: The top-5 leading causes of death among urban AI/AN persons were heart disease, cancer, unintentional injury, diabetes, and chronic liver disease and cirrhosis. Compared with urban White persons, urban AI/AN persons experienced significantly higher death rates for all top-5 leading causes. The largest disparities were for diabetes and chronic liver disease and cirrhosis. In general, urban and rural AI/AN persons had the same leading causes of death, although urban AI/AN persons had lower death rates for most conditions. CONCLUSIONS: Urban AI/AN persons experience significant disparities in death rates compared with their White counterparts. Public health and clinical interventions should target urban AI/AN persons to address behaviors and conditions contributing to health disparities.

Meeting the Challenges of Immunizing Adults.

The overall burden of illness from diseases for which vaccines are available disproportionately falls on adults. Adults are recommended to receive vaccinations based on their age, underlying medical conditions, lifestyle, prior vaccinations, and other considerations. Updated vaccine recommendations from CDC are published annually in the U.S. Adult Immunization Schedule. Vaccine use among U.S. adults is low. Although receipt of a provider (physician or other vaccinating healthcare provider) recommendation is a key predictor of vaccination, more often consumers report not receiving vaccine recommendations at healthcare provider visits. Although providers support the benefits of vaccination, they also report several barriers to vaccinating adults, including the cost of providing vaccination services, inadequate or inconsistent payment for vaccines and vaccine administration, and acute medical care taking precedence over preventive services. Despite these challenges, a number of strategies have been demonstrated to substantially improve adult vaccine coverage, including patient and provider reminders and standing orders for vaccination. Providers are encouraged to incorporate routine assessment of their adult patients' vaccination needs during all clinical encounters to ensure patients receive recommendations for needed vaccines and are either offered needed vaccines or referred for vaccination.

Meeting the Challenges of Immunizing Adults.

The overall burden of illness from diseases for which vaccines are available disproportionately falls on adults. Adults are recommended to receive vaccinations based on their age, underlying medical conditions, lifestyle, prior vaccinations, and other considerations. Updated vaccine recommendations from CDC are published annually in the U.S. Adult Immunization Schedule. Vaccine use among U.S. adults is low. Although receipt of a provider (physician or other vaccinating healthcare provider) recommendation is a key predictor of vaccination, more often consumers report not receiving vaccine recommendations at healthcare provider visits. Although providers support the benefits of vaccination, they also report several barriers to vaccinating adults, including the cost of providing vaccination services, inadequate or inconsistent payment for vaccines and vaccine administration, and acute medical care taking precedence over preventive services. Despite these challenges, a number of strategies have been demonstrated to substantially improve adult vaccine coverage, including patient and provider reminders and standing orders for vaccination. Providers are encouraged to incorporate routine assessment of their adult patients' vaccination needs during all clinical encounters to ensure patients receive recommendations for needed vaccines and are either offered needed vaccines or referred for vaccination.

Immunization information systems to increase vaccination rates: a community guide systematic review.

CONTEXT: Immunizations are the most effective way to reduce incidence of vaccine-preventable diseases. Immunization information systems (IISs) are confidential, population-based, computerized databases that record all vaccination doses administered by participating providers to people residing within a given geopolitical area. They facilitate consolidation of vaccination histories for use by health care providers in determining appropriate client vaccinations. Immunization information systems also provide aggregate data on immunizations for use in monitoring coverage and program operations and to guide public health action. EVIDENCE ACQUISITION: Methods for conducting systematic reviews for the Guide to Community Preventive Services were used to assess the effectiveness of IISs. Reviewed evidence examined changes in vaccination rates in client populations or described expanded IIS capabilities related to improving vaccinations. The literature search identified 108 published articles and 132 conference abstracts describing or evaluating the use of IISs in different assessment categories. EVIDENCE SYNTHESIS: Studies described or evaluated IIS capabilities to (1) create or support effective interventions to increase vaccination rates, such as client reminder and recall, provider assessment and feedback, and provider reminders; (2) determine client vaccination status to inform decisions by clinicians, health care systems, and schools; (3) guide public health responses to outbreaks of vaccine-preventable disease; (4) inform assessments of vaccination coverage, missed vaccination opportunities, invalid dose administration, and disparities; and (5) facilitate vaccine management and accountability. CONCLUSIONS: Findings from 240 articles and abstracts demonstrate IIS capabilities and actions in increasing vaccination rates with the goal of reducing vaccine-preventable disease.

Pneumonia and influenza mortality among American Indian and Alaska Native people, 1990-2009.

OBJECTIVES: We compared pneumonia and influenza death rates among American Indian/Alaska Native (AI/AN) people with rates among Whites and examined geographic differences in pneumonia and influenza death rates for AI/AN persons. METHODS: We adjusted National Vital Statistics Surveillance mortality data for racial misclassification of AI/AN people through linkages with Indian Health Service (IHS) registration records. Pneumonia and influenza deaths were defined as those who died from 1990 through 1998 and 1999 through 2009 according to codes for pneumonia and influenza from the International Classification of Diseases, 9th and 10th Revision, respectively. We limited the analysis to IHS Contract Health Service Delivery Area counties, and compared pneumonia and influenza death rates between AI/ANs and Whites by calculating rate ratios for the 2 periods. RESULTS: Compared with Whites, the pneumonia and influenza death rate for AI/AN persons in both periods was significantly higher. AI/AN populations in the Alaska, Northern Plains, and Southwest regions had rates more than 2 times higher than those of Whites. The pneumonia and influenza death rate for AI/AN populations decreased from 39.6 in 1999 to 2003 to 33.9 in 2004 to 2009. CONCLUSIONS: Although progress has been made in reducing pneumonia and influenza mortality, disparities between AI/AN persons and Whites persist. Strategies to improve vaccination coverage and address risk factors that contribute to pneumonia and influenza mortality are needed.

Influenza surveillance using electronic health records in the American Indian and Alaska Native population.

OBJECTIVE: Increasing use of electronic health records (EHRs) provides new opportunities for public health surveillance. During the 2009 influenza A (H1N1) virus pandemic, we developed a new EHR-based influenza-like illness (ILI) surveillance system designed to be resource sparing, rapidly scalable, and flexible. 4 weeks after the first pandemic case, ILI data from Indian Health Service (IHS) facilities were being analyzed. MATERIALS AND METHODS: The system defines ILI as a patient visit containing either an influenza-specific International Classification of Disease, V.9 (ICD-9) code or one or more of 24 ILI-related ICD-9 codes plus a documented temperature ≥100°F. EHR-based data are uploaded nightly. To validate results, ILI visits identified by the new system were compared to ILI visits found by medical record review, and the new system's results were compared with those of the traditional US ILI Surveillance Network. RESULTS: The system monitored ILI activity at an average of 60% of the 269 IHS electronic health databases. EHR-based surveillance detected ILI visits with a sensitivity of 96.4% and a specificity of 97.8% based on chart review (N=2375) of visits at two facilities in September 2009. At the peak of the pandemic (week 41, October 17, 2009), the median time from an ILI visit to data transmission was 6 days, with a mode of 1 day. DISCUSSION: EHR-based ILI surveillance was accurate, timely, occurred at the majority of IHS facilities nationwide, and provided useful information for decision makers. EHRs thus offer the opportunity to transform public health surveillance.

Vaccination coverage among American Indian and Alaska native children, 2006-2010.

BACKGROUND AND OBJECTIVES: A previous study on vaccination coverage in the American Indian/Alaska Native (AI/AN) population found that disparities in coverage between AI/AN and white children existed from 2001 to 2004 but were absent in 2005. The objective of this study was to describe vaccination coverage levels for AI/AN children aged 19-35 months in the United States between 2006 and 2010, examining whether gains found for AI/AN children in 2005 have been sustained. METHODS: Data from the 2006 through 2010 National Immunization Surveys were analyzed. Groups were defined as AI/AN (alone or in combination with any other race and excluding Hispanics) and white-only non-Hispanic children. Comparisons in demographics and vaccination coverage were made. RESULTS: Demographic risk factors often associated with underimmunization were significantly higher for AI/AN respondents compared with white respondents in most years studied. Overall, vaccination coverage was similar between the 2 groups in most years, although coverage with 4 or more doses of pneumococcal conjugate vaccine was lower for AI/AN children in 2008 and 2009, as was coverage with vaccine series measures the series in 2006 and 2009. When stratified by geographic regions, AI/AN children had coverage that was similar to or higher than that of white children for most vaccines in most years studied. CONCLUSIONS: The gains in vaccination coverage found in 2005 have been maintained. The absence of disparities in coverage with most vaccines between AI/AN children and white children from 2006 through 2010 is a clear success. These types of periodic reviews are important to ensure we remain vigilant.

Impact of rotavirus vaccine on diarrhea-associated disease burden among American Indian and Alaska Native children.

OBJECTIVE: Beginning in 2006, the Indian Health Service (IHS) began rotavirus vaccination of American Indian and Alaska Native (AI/AN) infants. To assess vaccine impact, we examined trends in IHS diarrhea-associated hospitalization and outpatient visits among AI/AN children in the pre- and postrotavirus vaccine era. METHODS: Diarrhea-associated hospitalizations and outpatient visits among AI/AN children <5 years of age during 2001 through 2010 were examined by gender, age group, and region for prevaccine years 2001-2006 and postvaccine years 2008, 2009, and 2010. To account for secular declining trends observed in prevaccine years, expected diarrhea-associated hospitalization and outpatient rates for postvaccine years were generated by using Poisson regression analysis of the 2001-2006 annual rates. RESULTS: Coverage with at least 1 dose of rotavirus vaccine among AI/AN infants aged 3 to 5 months in the first half of 2008, 2009, and 2010 ranged from 48% to 80% in various IHS regions. The prevaccine average annual diarrhea-associated hospitalization rates among AI/AN children <5 years of age was 63 per 10 000 persons (range: 57-75 per 10 000), and declined to 39, 31, and 27 per 10 000 in 2008, 2009, and 2010, respectively. Observed 2008, 2009, and 2010 rates were 24%, 37%, and 44% lower than expected rates, respectively. Decreases in diarrhea-associated hospitalizations and outpatient visits were observed in all IHS regions. CONCLUSIONS: Diarrhea-associated hospitalization and outpatient visit rates among AI/AN children have declined after implementation of rotavirus vaccination in AI/AN populations.

Human papillomavirus vaccination practices among providers in Indian health service, tribal and urban Indian healthcare facilities.

PURPOSE: The human papillomavirus (HPV) vaccine is of particular importance in American Indian/Alaska Native women because of the higher rate of cervical cancer incidence compared to non-Hispanic white women. To better understand HPV vaccine knowledge, attitudes, and practices among providers working with American Indian/Alaska Native populations, we conducted a provider survey in Indian Health Service, Tribal and Urban Indian (I/T/U) facilities. METHODS: During December 2009 and January 2010, we distributed an on-line survey to providers working in I/T/U facilities. We also conducted semistructured interviews with a subset of providers. RESULTS: There were 268 surveys and 51 provider interviews completed. Providers were more likely to administer vaccine to 13-18-year-olds (96%) than to other recommended age groups (89% to 11-12-year-olds and 64% to 19-26-year-olds). Perceived barriers to HPV vaccination for 9-18-year-olds included parental safety and moral/religious concerns. Funding was the main barrier for 19-26-year-olds. Overall, providers were very knowledgeable about HPV, although nearly half of all providers and most obstetricians/gynecologists thought that a pregnancy test should precede vaccination. Sixty-four percent of providers of patients receiving the vaccine do not routinely discuss the importance of cervical cancer screening. CONCLUSIONS: Recommendations for HPV vaccination have been broadly implemented in I/T/U settings. Vaccination barriers identified by I/T/U providers are similar to those reported in other provider surveys. Provider education efforts should stress that pregnancy testing is not needed before vaccination and the importance of communicating the need for continued cervical cancer screening.

Effects of a nationwide Hib vaccine shortage on vaccination coverage in the United States.

BACKGROUND: A shortage of Haemophilus influenzae type b (Hib) vaccine that occurred in the United States during December 2007 to September 2009 resulted in an interim recommendation to defer the booster dose, but to continue to vaccinate as recommended with the primary series during the first year of life. OBJECTIVES: To quantify effects of the Hib shortage on vaccination coverage and to determine if any demographic subgroups were disproportionately affected. METHODS: Data from the 2009 National Immunization Survey (NIS) were divided based on child's age at the onset of the shortage. Comparisons were made in primary series coverage by 9 months between children <7 months versus ≥7 months at the start of the shortage. Comparisons in primary series plus booster dose completion by 19 months were made between children who were <12 months versus ≥12 months at the start of the shortage. RESULTS: Nationally, there was a difference in Hib primary series completion by 9 months among children age <7 months versus ≥7 months at the start of the shortage (73.9% versus 81.2%, P<0.001). There was a large difference in the percentage of children fully vaccinated with the primary series plus booster dose by 19 months among children age <12 months versus ≥12 months at the start of the shortage (39.5% versus 66.0%, P<0.001). There were differential effects of the shortage on primary series coverage among states and for some demographic characteristics. CONCLUSIONS: As expected booster dose coverage was reduced consistent with interim recommendations, but primary series coverage was also reduced by 7 percentage points nationally.

Validation of algorithm to identify American Indian/Alaska Native pregnant women at risk from pandemic H1N1 influenza.

Pregnant women and American Indian and Alaska Native people are at elevated risk of severe disease and mortality from 2009 pandemic influenza A/H1N1. We validated an electronic health record-based algorithm used by Indian Health Service to identify pregnant women in near real-time surveillance of pandemic influenza A/H1N1. We randomly selected a stratified sample of 515 patients at 3 Indian Health Service-funded hospitals with varied characteristics. With comprehensive review of patients' electronic health records as the gold standard, we calculated the positive predictive value and sensitivity of the pregnancy algorithm. The sensitivity of the algorithm at individual hospitals ranged from 94.1-96.0%. Positive predictive value ranged from 94.4-98.3%. Despite differences among hospitals on key characteristics, the pregnancy algorithm performed nearly equivalently with high positive predictive value and sensitivity at all facilities. It may prove helpful for surveillance during future epidemics and for targeting interventions for pregnant women and infants.

Pandemic influenza preparedness and vulnerable populations in tribal communities.

American Indian and Alaska Native (AIAN) governments are sovereign entities with inherent authority to establish and administer public health programs within their communities and will be critical partners in national efforts to prepare for pandemic influenza. Within AIAN communities, some subpopulations will be particularly vulnerable during an influenza pandemic because of their underlying health conditions, whereas others will be at increased risk because of limited access to prevention or treatment interventions.We outline potential issues to consider in identifying and providing appropriate services for selected vulnerable populations within tribal communities. We also highlight pandemic influenza preparedness resources available to tribal leaders and their partners in state and local health departments, academia, community-based organizations, and the private sector.

Underimmunization of American Indian and Alaska Native children.

OBJECTIVE: The goal was to determine whether disparities in childhood immunization coverage exist between American Indian/Alaska Native children and non-Hispanic white children. METHODS: We compared immunization coverage with the 4 diphtheria-tetanus-pertussis, 3 poliovirus, 1 measles-mumps-rubella, 3 Haemophilus influenza type b, and 3 hepatitis B(4:3:1:3:3) series and its individual vaccine components (> or = 4 doses of diphtheria, tetanus, and pertussis vaccine; > or = 3 doses of oral or inactivated polio vaccine; > or = 1 dose of measles, mumps, and rubella vaccine; > or = 3 doses of Haemophilus influenzae type b vaccine; and > or = 3 doses of hepatitis B vaccine) between American Indian/Alaska Native children and non-Hispanic white children from 2000 to 2005, using data from the National Immunization Survey. RESULTS: Although immunization coverage increased for both populations from 2001 to 2004, American Indian/Alaska Native children had significantly lower immunization coverage, compared with non-Hispanic white children, over that time period. In 2005, coverage continued to increase for American Indian/Alaska Native children but decreased for non-Hispanic white children, and no statistically significant disparity in 4:3:1:3:3 coverage was evident in that year. CONCLUSIONS: Disparities in immunization coverage for American Indian/Alaska Native children have been present, but unrecognized, since 2001. The absence of a disparity in coverage in 2005 is encouraging but is tempered by the fact that coverage for non-Hispanic white children decreased in that year.

Status of influenza and pneumococcal vaccination among older American Indians and Alaska Natives.

OBJECTIVES: We sought to estimate the influenza and pneumococcal vaccination coverage among older American Indian and Alaska Native (AIAN) adults nationally and the impact of sociodemographic factors, variations by geographic region, and access to services on vaccination coverage. METHODS: We obtained our sample of 1981 AIAN and 179845 White respondents 65 years and older from Behavioral Risk Factor Surveillance System data from 2003 to 2005. Logistic regression provided predictive marginal vaccination coverage for each covariate and adjusted for demographic characteristics and access to care. RESULTS: Unadjusted influenza coverage estimates were similar between AIAN and White respondents (68.1% vs 69.5%), but pneumococcal vaccination was lower among AIAN respondents (58.1% vs 67.2%; P<.01). After multivariable adjustment for sociodemographic characteristics, self-reported coverage for both vaccines was statistically similar between AIAN and White adults. CONCLUSIONS: Although there was no disparity in influenza coverage, pneumococcal coverage was lower among AIAN than among White respondents, probably because of sociodemographic risk factors. Regional variation indicates a need to monitor coverage and target interventions to reduce disparities within geographically and culturally diverse subpopulations of AIAN persons.

Effect of a national vaccine shortage on vaccine coverage for American Indian/Alaska Native children.

OBJECTIVES: We determined the effect of national vaccine shortages on coverage with 4 doses of diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine for American Indian/Alaska Native (AIAN) children. METHODS: Data on DTaP coverage for children aged 19 to 27 months were abstracted from Indian Health Service (IHS) immunization reports. Coverage with the fourth DTaP dose (DTaP4) was compared for different periods to determine coverage levels before, during, and after the shortage. Data were stratified geographically to determine regional variation. RESULTS: AIAN children experienced a significant decline (14.8%) in DTaP4 coverage during the shortage. Considerable variation was seen among IHS regions (declines ranged from 4.5% to 26.5%). CONCLUSIONS: AIAN children included in IHS immunization reports experienced a greater decline in DTaP4 coverage during the shortage than the decline reported nationally for children receiving vaccine at public clinics (14.8% vs 6%). Variations in the decline in coverage highlight possible inequities in vaccine supply and distribution and in implementation of vaccine shortage recommendations. We must identify ways to ensure more equitable vaccine distribution and consistent implementation of vaccine recommendations to protect all children from vaccine-preventable diseases.

Factors associated with fulminant liver failure during an outbreak among injection drug users with acute hepatitis B.

Death related to acute hepatitis B occurs in approximately 1% of patients. We investigated an outbreak of hepatitis B virus (HBV) infections among injection drug users (IDUs) resulting in several deaths. We conducted a case-control study of fulminant (case patients) and nonfulminant (control patients) HBV infections. We directly sequenced the entire HBV genome from fulminant and nonfulminant cases. From October 1998 to July 2000, 21 acute HBV infections, including 10 fulminant hepatitis B cases, were identified. The median age was 30 (range, 18-49) years, 12 (57%) were female, 20 (95%) were American Indians, and 20 (95%) reported injecting illicit drugs. All patients with fulminant hepatitis B died (case-fatality rate = 47.6%). Case patients (n = 5) and control patients (n = 9) were similar with respect to age, sex, race, and hepatitis C virus serostatus. All case patients used acetaminophen during their illness compared with 44% of control patients (P =.08). Compared with control patients, case patients lost more weight in the 6 months before illness (P =.04); during their illness, they used more alcohol (P =.03) and methamphetamine (P =.04). All 9 isolates sequenced were genotype D, shared 99.7% homology, and included mutations previously described in association with fulminant hepatitis B. In conclusion, a high prevalence of exposure to factors potentiating hepatic damage with acute hepatitis B contributed to the outbreak's high mortality rate; mutations present in the outbreak strain might also have been a factor. Improved vaccination coverage among IDUs has the potential to prevent similar outbreaks in the future.