Elimination of hepatitis a infection outbreaks in day care and school settings in southern Israel after introduction of the national universal toddler hepatitis a immunization program.
BACKGROUND
In 1999, Israel became the first country to begin universal toddler immunization against hepatitis A infection with a 2-dose schedule at 18 and 24 months. The effect of the Israeli program on outbreaks of Hepatitis A in day care and school settings was studied.


METHODS
The records of all hepatitis A illness outbreaks in day care and school settings reported to the Ministry of Health in Southern Israel during 1993 through 2005 were reviewed. The number of exposed contacts for whom postexposure prophylaxis was administered was retrieved from records of epidemiologic investigations. Rates of immunization coverage were extracted from records of Maternal and Child Health Clinics.


RESULTS
Three hundred nineteen cases of hepatitis A illness during the years 1993 through 2005 were associated with 113 outbreaks in day care and school settings of which 92% occurred before the institution of universal toddler immunization. Since 2000, no hepatitis A infection outbreaks have been reported in any day care and school settings in the region. An average of 732 children received immunoglobulin prophylaxis yearly because of exposure to an outbreak in an educational setting during the preimmunization period, 106 in 2000 and zero in the 5 years since 2001. The data showed marked herd immunity since school-aged children born before 1999 were not immunized, but elimination of outbreaks occurred equally in that age group. Immunization coverage was 86.4% for one dose of hepatitis A vaccine by age 3 years and 77.3% for 2 doses among the birth cohort of 2000.


CONCLUSIONS
Universal hepatitis A immunization of toddlers was associated with disappearance of outbreaks in educational settings. This included cohorts of nonimmunized children representing marked herd immunity.
Belmaker
Ilana
I
Ministry of Health, Southern Regional Office, Beer Sheva, Israel. ilna.belmaker@lbr.health.gov.il
Dukhan
Larissa
L
Yosef
Yochi
Y
Leventhal
Alex
A
Dagan
Ron
R
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003631:Day Care, Medical; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control*; D022362:Hepatitis A Vaccines / Q000627:therapeutic use*; D017957:Hepatitis A Virus, Human / Q000276:immunology*; D006801:Humans; D032521:Immunity, Herd; D015994:Incidence; D007223:Infant; D007557:Israel / Q000453:epidemiology; D008297:Male; D012574:Schools
D022362:Hepatitis A Vaccines