Research Summary

Hepatitis A and B Serologic Immunity Low Among US Adults in Cross-Sectional Study

Edited by:
Brian McCurdy

Key Highlights

  • Among 13,514 participants, 25.2% had vaccine-derived hepatitis B immunity.
  • Hepatitis A immunity ranged from 26.7% to 63.7% across high-risk clinical subgroups.
  • Vaccine-derived hepatitis B immunity was lowest among participants with chronic kidney disease, at 14%.

Fewer than half of US adults demonstrated serologic immunity to hepatitis A virus (HAV), and approximately one-quarter demonstrated immunity to hepatitis B virus (HBV), according to a cross-sectional study published in JAMA Internal Medicine. The analysis also identified substantial gaps in immunity among populations with conditions that increase their clinical vulnerability.

Researchers analyzed National Health and Nutrition Examination Survey data collected from January 2017 through August 2023. The study included adults aged ≥20 years with available HAV and HBV serologic results. Its 13,514 participants represented approximately 226.1 million US adults; the mean age was 48.65 years, and 51.76% were female.

HAV immunity was defined as hepatitis A antibody positivity. HBV immunity was defined as hepatitis B surface antibody positivity, while vaccine-derived HBV immunity required surface antibodies without hepatitis B core antibodies. Investigators generated nationally representative weighted estimates and used multivariable survey-weighted logistic regression to examine associated factors. High-risk subgroups included people with chronic liver disease, chronic kidney disease, diabetes, or immunosuppression, and pregnant people.

Study Findings

HAV serologic immunity was present in 39.5% of adults (95% CI, 37.7%-41.3%), corresponding to 89.4 million people. HBV serologic immunity was present in 27.1% (95% CI, 25.8%-28.4%), corresponding to 61.3 million people. Vaccine-derived HBV immunity was identified in 25.2% (95% CI, 23.9%-26.5%). In adjusted analyses, birth outside the US was associated with higher odds of HAV immunity (adjusted odds ratio [AOR], 4.54; 95% CI, 3.74-5.52), while obesity was associated with lower odds (AOR, 0.83; 95% CI, 0.72-0.96).

Among high-risk subgroups, HAV immunity ranged from 26.7% (95% CI, 18.9%-34.4%) in those with metabolic dysfunction–associated alcohol-related liver disease to 63.7% (95% CI, 50.0%-77.4%) in those with chronic HBV infection. Vaccine-derived HBV immunity ranged from 14% (95% CI, 11.3%-16.6%) among participants with chronic kidney disease to 38.6% (95% CI, 28.0%-49.1%) among pregnant participants. These estimates describe the serologic outcomes reported in the study.

Clinical Implications

According to the study authors, population-level HAV and HBV serologic immunity was suboptimal, and substantial susceptibility persisted across high-risk clinical subgroups. They interpreted the findings as support for targeted, systematic vaccination strategies, especially among high-risk populations.

Expert Commentary

“These findings highlight persistent gaps in viral hepatitis protection and support targeted, systematic vaccination strategies for HAV and HBV, especially among high-risk populations,” the researchers concluded.

Reference

Roldan GA, Fletcher J, Davie T. Serologic immunity to hepatitis A and B in US adults and high-risk populations. JAMA Intern Med. 2026;186(10):1213-1223. doi:10.1001/jamainternmed.2026.3831