What are the modes of transmission and prevention strategies for hepatitis A in children?

How Hepatitis A Spreads in Children

Hepatitis A spreads primarily through the fecal-oral route via person-to-person contact, with children playing a critical role as they often have asymptomatic infections but remain highly contagious, particularly in household and childcare settings. 1

Primary Transmission Routes

Person-to-Person Spread

• Direct fecal-oral transmission is the dominant mode of spread, occurring through close personal contact with infected individuals 1, 2
• Children are key vectors because infection in young children is typically asymptomatic or mild, yet they shed virus and transmit to older family members who then develop symptomatic disease 1
• Transmission is generally limited to close contacts; casual interactions rarely spread the virus 1
• In 52% of adult hepatitis A cases with unknown source, a child under 6 years was present in the household 2

Childcare Center Transmission

• Poor hygiene among diapered children and diaper-changing by staff are the primary mechanisms of spread in childcare settings 1
• Outbreaks are identified when adult contacts (typically parents) become ill, since the children themselves often remain asymptomatic 1
• Outbreaks rarely occur in centers caring only for toilet-trained children 1

Foodborne Transmission

• Contamination occurs when infected food handlers touch uncooked foods or foods after cooking, particularly if they have diarrhea or poor hygiene 1
• A single infected food handler can transmit to dozens or hundreds of people 1
• Raw produce (especially green onions) contaminated before reaching food establishments has become an increasingly recognized source 1

Rare Transmission Routes

• Bloodborne transmission can occur through transfusion during the viremic phase, though this is uncommon 1
• Waterborne outbreaks are rare in developed countries with adequate sanitation 1

Period of Infectivity

Children are most infectious from 14-21 days before jaundice onset to approximately 8 days after, with peak viral shedding occurring before symptoms appear 1, 2

• Children can shed virus for up to 10 weeks after clinical illness onset 1, 2
• This prolonged shedding period makes children particularly effective at spreading infection within families and childcare settings 1
• Viral RNA can be detected in stool by PCR for up to 3 months after acute illness 1

Prevention Strategies in Children

Vaccination (Primary Prevention)

Routine hepatitis A vaccination should be administered to all children at 12-23 months of age, with catch-up vaccination for children and adolescents aged 2-18 years who have not previously received the vaccine 3

• Vaccination provides long-term immunity and has virtually eliminated age, ethnic, racial, and regional differences in hepatitis A incidence in the United States 1
• The dramatic success of childhood vaccination programs has significantly dampened epidemic patterns 1

Hygiene Measures

Thorough handwashing is the cornerstone of prevention, particularly after diaper changes, toileting, and before food preparation 4

• Surfaces should be disinfected using a 1:100 dilution of household bleach in tap water 2
• Foods must be heated to temperatures above 185°F (85°C) for at least 1 minute to inactivate the virus 2

Postexposure Prophylaxis

Unvaccinated children exposed to hepatitis A should receive immune globulin (IG) at 0.02 mL/kg as soon as possible, ideally within 2 weeks of exposure 1

• For children ≥12 months who are being administered IG, hepatitis A vaccine may be given simultaneously at a separate injection site 1
• Children <12 months should receive IG alone, as vaccine is not licensed for this age group 5

Childcare Center Outbreak Control

When one or more cases are recognized in children or employees, IG should be administered to all previously unvaccinated staff and attendees 1

• If cases are recognized in two or more households of center attendees, IG should be given to all unvaccinated staff and children 1
• When outbreaks occur (cases in three or more families), consider IG for household members with diapered children attending the center 1
• Hepatitis A vaccine may be administered simultaneously with IG during childcare outbreaks 1

Household Contact Management

All previously unvaccinated household contacts of a child with serologically confirmed hepatitis A should receive IG 1

• Regular babysitters and others with ongoing close personal contact should also be considered for IG 1
• Serologic confirmation with IgM anti-HAV testing is recommended before treating contacts 1

Critical Pitfalls to Avoid

• Do not delay postexposure prophylaxis for immunity screening—screening causes delays and IG efficacy has not been established beyond 2 weeks after exposure 1
• Do not assume school-based transmission—cases in elementary or secondary schools typically reflect community acquisition, and child-to-child transmission in schools is uncommon 1
• Do not overlook international travel as a source—children visiting family in endemic countries are a common but underrecognized source of infection, accounting for >25% of cases in children <15 years in 2003 1
• Do not assume symptomatic children are the only spreaders—asymptomatic infected children are the primary drivers of household and childcare outbreaks 1, 2