Just 39.5% of U.S. adults demonstrated serologic immunity to the hepatitis A virus and only 27.1% had immunity to the hepatitis B virus, according to cross-sectional study results published in JAMA Internal Medicine. Healio reported that high-risk groups, including individuals with chronic liver disease, exhibited lower immunity levels than the general population despite decades of vaccine availability.
The study, which analyzed National Health and Nutrition Examination Survey data from 13,514 adults between January 2017 and August 2023, underscores a critical population-level protection gap across the United States. Giovanni A. Roldan, an advanced endoscopy fellow at Baylor College of Medicine, noted that contemporary national estimates were previously limited, particularly for high-risk cohorts such as pregnant individuals and those with immunosuppressive therapy or chronic kidney disease.
In Plain English: The Clinical Takeaway
- Serologic Immunity Explained: Serologic immunity means having detectable antibodies in the blood that protect against a specific infection, either from a past vaccination or a healed prior illness.
- Suboptimal Protection: Less than 40% of American adults have blood markers protecting them against hepatitis A, and barely over a quarter are protected against hepatitis B.
- Clinical Disconnect: Even patients with chronic liver disease—who face severe complications if infected—showed hepatitis A immunity dropping as low as 26.7%, revealing major gaps in routine healthcare delivery.
National Survey Data Reveals Low Baseline Protection Rates
Researchers estimated that the study sample represented more than 226 million American adults. Out of that broader population, only 25.2% demonstrated vaccine-derived immunity specifically against hepatitis B. The investigation was initiated following recent adjustments to national immunization policies, specifically the December 2025 shift by the Centers for Disease Control and Prevention and the Advisory Committee on Immunization Practices regarding hepatitis B birth dose guidelines.
Historically, the universal birth dose recommendation adopted in 1991 led to a 95% reduction in infant hepatitis B infections. However, current adult baseline numbers indicate that protection erodes or fails to establish adequately as populations age or interact with fragmented care systems. Two-thirds of U.S. adults fell into a designated high-risk subgroup, yet their immunological protection varied widely depending on their specific underlying health conditions.
Structured Access Correlates With Higher Antibody Levels
Immunity markers fluctuated significantly across different high-risk clinical populations. Hepatitis A immunity among high-risk subgroups spanned from 26.7% to 63.7%, while vaccine-derived hepatitis B immunity ranged between 14% and 38.6%. Individuals managing advanced chronic kidney disease and pregnant patients stood out with notably higher protection rates than the general public.
Advanced chronic kidney disease patients exhibited 53.9% hepatitis A immunity and 32.3% hepatitis B immunity. Pregnant individuals demonstrated 38.6% hepatitis B immunity. Giovanni A. Roldan explained that these groups often encounter more structured, frequent touchpoints within the healthcare system, demonstrating that the vaccines themselves remain highly effective when delivery systems function properly.
Demographic and Behavioral Factors Shaping Immunity
Statistical models identified multiple independent variables associated with serologic protection against hepatitis A. Younger age, lower educational attainment, and obesity correlated with lower odds of maintaining protective antibodies. Specifically, data linked obesity to an adjusted odds ratio of 0.83 for hepatitis A immunity.
Conversely, being born outside the United States dramatically increased the odds of HAV immunity, yielding an adjusted odds ratio of 4.54. Specific ethnic backgrounds also showed higher association, including non-Hispanic Black, Mexican American, other Hispanic, and non-Hispanic Asian adults. Furthermore, individuals with prior liver disease awareness showed higher odds of possessing hepatitis A immunity, pointing toward targeted vaccination efforts following clinical diagnoses.
References
- JAMA Internal Medicine: Serologic Immunity to Hepatitis A and B Viruses in U.S. Adults.
- Centers for Disease Control and Prevention (CDC): Advisory Committee on Immunization Practices (ACIP) Guidelines.
- National Health and Nutrition Examination Survey (NHANES): Data Collection Protocols.
Disclaimer: This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.
