title: Decreasing immunity to hepatitis A virus infection among US adults: Findings from the National Health and Nutrition Examination Survey (NHANES), 1999-2012.
abstract: BACKGROUND
  The clinical course of hepatitis A virus (HAV) infection is more severe with increased age. In the United States, surveillance data reported to CDC since 2011 indicate increases in both the absolute number of cases and the mean age of cases. Total antibody to HAV (anti-HAV) is a marker of immunity.
  
  
  METHODS
  We analyzed National Health and Nutrition Examination Survey (NHANES) data for anti-HAV from respondents aged ≥ 2 years collected from 2007 to 2012 and compared with data collected 10 years earlier (1999-2006). For US-born adults aged ≥ 20 years, we estimated age-adjusted anti-HAV prevalence by demographic and other characteristics, evaluated factors associated with anti-HAV positivity and examined anti-HAV prevalence by decade of birth.
  
  
  RESULTS
  The prevalence of anti-HAV among adults aged ≥ 20 years was 24.2% (95% CI 22.5-25.9) during 2007-2012, a significant decline from 29.5% (95% CI 28.0-31.1) during 1999-2006. Prevalence of anti-HAV was consistently lower in 2007-2012 compared to 1999-2006 by all characteristics examined. In 2007-2012, the lowest age-specific prevalence was among adults aged 30-49 years (16.1-17.6%). Factors significantly associated with anti-HAV positivity among adults were older age, Mexican American ethnicity, living below poverty, less education, and not having insurance. By decade of birth, the prevalence of anti-HAV was slightly lower in 2009-2012 than in 1999-2002, except among persons born from 1980 to 1989.
  
  
  CONCLUSIONS
  NHANES data document very low prevalence of hepatitis A immunity among U.S. adults aged 30-49 years; waning of anti-HAV over time may be minimal. Improving vaccination coverage among susceptible adults should be considered.
authors.affiliation: Division of Viral Hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, NE, Mailstop G-37, Atlanta, GA 30329, United States. Electronic address: monina.klevens@state.ma.us.
authors.forename: R Monina
authors.initials: RM
authors.lastname: Klevens
authors.affiliation: Division of Viral Hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, NE, Mailstop G-37, Atlanta, GA 30329, United States.
authors.forename: Maxine M
authors.initials: MM
authors.lastname: Denniston
authors.affiliation: Division of Viral Hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, NE, Mailstop G-37, Atlanta, GA 30329, United States.
authors.forename: Ruth B
authors.initials: RB
authors.lastname: Jiles-Chapman
authors.affiliation: Division of Viral Hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, NE, Mailstop G-37, Atlanta, GA 30329, United States.
authors.forename: Trudy V
authors.initials: TV
authors.lastname: Murphy
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006506:Hepatitis A / Q000517:prevention & control*; D035922:Hepatitis A Antibodies / Q000097:blood*; D030041:Hepatitis A virus / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D016036:Seroepidemiologic Studies; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies
keywords: Adults; Children; Hepatitis A virus; Seroprevalence; US