Predictors of hepatitis A immunity in adults in California in order to better utilize hepatitis A vaccine.

BACKGROUND Hepatitis A vaccine recommendations now include homelessness, illegal drug use, and HIV, as well as traditional risk factors and travel to areas endemic for hepatitis A. We examined a large diverse population for predictors of Hepatitis A immunity in order to better utilize Hepatitis A vaccine. METHODS We performed a cross-sectional descriptive study of members of a large integrated health plan with a test for Hepatitis A Immunoglobulin G (IgG) between January 1st, 2007, and December 31st, 2017. Exclusion criteria included age <18 years, <6 months of continuous enrollment, and Hepatitis A vaccine prior to Hepatitis A test. Variables of interest were age, gender, primary language spoken, ethnicity/race, neighborhood household income, and history of travel or history of jaundice. Multivariable logistic regression was performed to evaluate the association of risk factors on Hepatitis A immunity. RESULTS Of the 318,170 persons ≥ 18 years tested for Hepatitis A immunity, 155, 842 persons had a reactive Hepatitis A IgG test (49%). The lowest prevalence was for Whites at 28.1% followed by Blacks at 35.8%. Hispanics and Asian/Pacific Islanders had prevalence rates of 63% and 68.2% respectively. In adjusted analyses, Asian/Pacific Islanders, Hispanics and Blacks were 5.17, 3.44 and 1.42 times more likely to have Hepatitis A immunity than Whites. Those that spoke Spanish or language other than English or Spanish as their primary preferred language were 6.11 and 3.27 time more likely to have immunity than English speakers. Known travel history conferred a 2.16 likelihood of Hepatitis A immunity. CONCLUSIONS Persons of Hispanic and Asian/Pacific Islander background as well as persons with a preferred spoken language other than English have a high prevalence of Hepatitis A immunity. Testing for Hepatitis A immunity prior to vaccination should be considered for these groups.