Hepatitis A and Hepatitis A Vaccine Epidemiology and Prevention of Vaccine- Preventable Diseases National Immunization Program Centers for Disease Control and Prevention Revised March 2002

Hepatitis A Epidemic jaundice described by Hippocrates Differentiated from hepatitis B in 1940s Serologic tests developed in 1970s Most commonly reported type of hepatitis in the United States

Hepatitis A Virus Picornavirus (RNA) Humans are only natural host Stable at low pH Inactivated by high temperature, formalin, chlorine

Hepatitis A Pathogenesis Entry into mouth Viral replication in the liver Virus present in blood and feces days after infection Virus excretion may continue for up to 3 weeks after onset of symptoms

Incubation period 28 days (range days) Illness not specific for hepatitis A Likelihood of symptomatic illness directly related to age Children generally asymptomatic, adults symptomatic Hepatitis A Clinical Features

Hepatitis A Epidemiology Reservoir Human. Endemic Transmission Fecal-oral Temporal pattern None Communicability2 weeks before to 1 week after onset

Source of Hepatitis A Infection

Hepatitis A – United States, * Vaccine Licensed *2001 provisional data

Hepatitis A Incidence* by Age Group *rate per 100,000 population data.

Hepatitis A Incidence - United States and American Indians, Source: National Notifiable Diseases Surveillance System, CDC American Indians United States Vaccine Licensed ACIP Recommendation

Inactivated whole virus HAVRIX (GlaxoSmithKline) VAQTA (Merck Vaccine Division) Pediatric and adult formulations Licensed for persons >2 years Hepatitis A Vaccines

Formulation Pediatric age dose Adult age dose HAVRIX 2-18 yrs 0.5 ml >18 yrs 1.0 ml VAQTA 2-18 yrs 0.5 ml >18 yrs 1.0 ml

Hepatitis A Vaccine Immunogenicity 95% seropositive after one dose 100% seropositive after two doses >97% seropositive after one 100% seropositive after 2 doses Adults Children (>2 years) and Adolescents

Hepatitis A Vaccine Efficacy 40,000 Thai children 4-15 years Vaccine efficacy 94% 1,000 children 2-16 years Vaccine efficacy 100% GlaxoSmithKline Merck

Hepatitis A Vaccines 1 dose Booster dose months after first dose 1 dose Booster dose months after first dose Adult Children and Adolescent

Children >2 years in states, counties, or communities where the average annual hepatitis A rate during was >20 per 100,000 population Hepatitis A Vaccine Recommendations Routine hepatitis A vaccination is recommended for:

Hepatitis A Vaccination Strategies High Incidence States One or more single age cohorts of children or adolescents Children in settings such as day care Children and adolescents in a wide range of ages in a variety of settings, such as when they seek health care for other purposes

Children >2 years in states, counties, or communities where the average annual hepatitis A rate during was 10 to 20 per 100,000 population Routine hepatitis A vaccination should be considered for: Hepatitis A Vaccine Recommendations

Hepatitis A Vaccination Strategies Intermediate Incidence States Statewide or community-based? Clustering of high-incidence areas within the state Feasibility Impact on incidence

Hepatitis A – High Incidence States

Twinrix Combination hepatitis B (adult dose) and hepatitis A vaccine (pediatric dose) Schedule: 0, 1, 6-12 months Approved for persons >18 years

International travelers Men who have sex with men Drug users Persons with occupational risk Persons with chronic liver disease, including hepatitis C Hepatitis A Vaccine Recommendations

Travelers to high or intermediate risk countries Protected by 4 weeks after dose Give concurrent IG for travel in <4 weeks Hepatitis A Vaccine Recommendations

Health care workers: not routinely recommended Day care centers: not routinely recommended Food handlers: may be considered based on local circumstances Hepatitis A Vaccine Recommendations

Hepatitis A Serologic Testing Not indicated for children May be considered for some adults and older adolescents Not indicated Prevaccination Postvaccination

Hepatitis A Vaccine Adverse Reactions Pain at injection site Systemic reactions uncommon No serious adverse events reported

Severe allergy to vaccine component or following prior dose Moderate or severe acute illness Hepatitis A Vaccine Contraindications and Precautions

National Immunization Program Hotline Websitewww.cdc.gov/nip