National Progress Report 2025 Goal: Reduce estimated* new hepatitis A virus infections by ≥40%

Source: CDC, National Notifiable Diseases Surveillance System
*The number of estimated viral hepatitis infections was determined by multiplying the number of reported cases by a factor that adjusted for underascertainment and underreporting (1–2).

Summary of Findings

The number of estimated new hepatitis A virus (HAV) infections has increased since 2014, and in 2019 the estimated number of infections had increased to 5.6 times that of the 2017 baseline. As the number of infections in 2019 was estimated to be 37,700, the 2019 target of 5,800 was not met. The incidence of hepatitis A is subject to variation from year to year, in large part due to hepatitis A outbreaks. Since late 2016, there have been widespread outbreaks of hepatitis A across the United States, spread through person-to-person contact primarily among persons reporting drug use or homelessness. These community outbreaks have been prolonged and difficult to control in many states, highlighting the importance of administering hepatitis A vaccine in populations that have been put at increased risk for infection. Outbreaks associated with foods, such as outbreaks that occurred in 2013 in several southwestern states and Hawaii among persons who consumed imported pomegranate seeds, two outbreaks that occurred in early 2016 among persons who consumed imported frozen strawberries or raw scallops, and a 2019 outbreak in seven states linked to fresh blackberries, accounted for far fewer cases, occurred in fewer states, and had much shorter durations than the ongoing outbreaks driven by person-to-person transmission.

Reduction needed to meet 2025 goal: An 89.4% reduction from the estimated number of HAV infections in 2019 is needed to meet the 2025 goal of 4,000 estimated infections.

This reduction can best be achieved by

• Disseminating and implementing recently updated CDC recommendations for hepatitis A vaccination (including post‑exposure prophylaxis) to reach populations experiencing emerging or increasing risk of infection.
• Strengthening state and local health departments’ outbreak detection and response.
• Promoting evidence-based strategies to increase vaccination as recommended by the Community Preventive Services Task Force.
• Analyzing available data and other strategic information to detect populations with higher risk of infection and gaps in vaccination coverage.
• Continuing to promote routine childhood vaccination schedules and vaccination of adults at increased risk for hepatitis A according to Advisory Committee on Immunization Practices (ACIP) Vaccine Recommendations and Guidelines.

Technical Notes

Data Sources: CDC, National Notifiable Diseases Surveillance System (NNDSS)

Numerator: Number of estimated HAV infections

Denominator: Not applicable

Indicator Notes: (1) The NNDSS is a nationwide collaboration that enables all levels of public health to share notifiable-disease-related health information. Surveillance for viral hepatitis through NNDSS is based on case definitions developed and approved by the Council of State and Territorial Epidemiologists (CSTE) and CDC. Reported cases of acute viral hepatitis A are required to meet specific clinical and laboratory criteria. Estimated infections are based on laboratory-confirmed reports of acute viral hepatitis. Hepatitis A is reportable in all jurisdictions. Health care providers, hospitals, and/or laboratories report cases to the local or state health department, and states voluntarily submit reports or notify CDC of newly diagnosed cases of hepatitis A that meet the CSTE/CDC surveillance case definition. To account for underascertainment and underreporting, the number of reported cases is multiplied by 2.0. The methods for developing the multiplication factor are documented in Klevens, et al (2) with corrected multipliers developed by CDC (1).

Goal Setting: The 2025 goal of 4,000 estimated infections is consistent with CDC’s Division of Viral Hepatitis 2025 Strategic Plan and HHS’s 2021-2025 Viral Hepatitis National Strategic Plan. Annual targets assume a constant (linear) rate of change from the observed baseline (2017 data year) to the 2025 goal (2023 data year).

Limitations: The number of estimated infections is based on a simple, probabilistic model for estimating the proportion of patients who were symptomatic, received testing, and were reported to health officials in each year (2). This constant multiplier may not account for variations over time in underreporting and underascertainment due to changes in public and provider awareness, laboratory and diagnostic techniques, and the definition of the condition.

References

1. Centers for Disease Control and Prevention. Viral Hepatitis Surveillance—United States, 2019. Atlanta: US Department of Health and Human Services, Centers for Disease Control and Prevention; 2021. Available at: https://www.cdc.gov/hepatitis/statistics/2019surveillance/index.htm.
2. Klevens RM, Liu S, Roberts H, Jiles RB, Holmberg SD. Estimating acute viral hepatitis infections from nationally reported cases. Am J Public Health. 2014;104(3):482-7.