A program to control an outbreak of hepatitis A in Alaska by using an inactivated hepatitis A vaccine.
OBJECTIVE
To stop an epidemic of hepatitis A in rural Alaska by mass immunization of susceptible persons with 1 dose of an inactivated hepatitis A vaccine.


METHODS
Nonrandomized, uncontrolled trial. Hepatitis A vaccine was offered to all persons in susceptible age groups in villages with documented cases of hepatitis A. Immune globulin was not offered at the time of vaccination.


METHODS
Twenty-five rural communities located in interior Alaska and along the northwest coast of the Bering Sea and Arctic Ocean.


METHODS
Persons without a history of acute hepatitis A in age groups selected by applying results of a previous serosurvey conducted on serum collected before the epidemic.


METHODS
One dose of a formalin-inactivated hepatitis A vaccine was given to each participant. Adults 20 years of age and older received 1440 enzyme-linked immunosorbent assay units and persons younger than 20 years received 720 enzyme-linked immunosorbent assay units. Prevaccination and postvaccination levels of antibody to hepatitis A IgG were obtained from 136 participants.


METHODS
An active surveillance system was established to detect persons with symptomatic illnesses compatible with hepatitis A; persons who met the illness criteria were tested for antibody to hepatitis A IgM. One area (the Kotzebue region), where all communities were offered vaccine, was selected for intensive surveillance and analysis.


RESULTS
During the 12-month period before the vaccine trial, 529 cases of icteric hepatitis A were reported, and 443 were confirmed to be positive for antibody to hepatitis A IgM. Hepatitis A vaccine was administered to 4930 persons, 3517 of whom were younger than 20 years. After vaccination began, 237 persons positive for antibody to hepatitis A IgM were identified during a 60-week surveillance period; 46 were vaccines and 191 were unvaccinated susceptible persons. In the Kotzebue region, in communities in which more than 80% of persons considered susceptible were vaccinated, the outbreak ceased in 4 to 8 weeks, whereas in 1 large community in which less than 50% of susceptible persons were vaccinated, the outbreak continued for more than 50 weeks. More than 90% of seronegative persons developed antibody to hepatitis A IgG 3 to 4 weeks after vaccination.


CONCLUSIONS
This trial suggested that by providing both short-term and long-term protection, hepatitis A vaccine used without immune globulin halted an established epidemic of hepatitis A in rural Alaska.
McMahon
B J
BJ
Alaska Native Medical Center, Indian Health Service, Anchorage, USA.
Beller
M
M
Williams
J
J
Schloss
M
M
Tanttila
H
H
Bulkow
L
L
D000293:Adolescent; D000328:Adult; D000413:Alaska / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology* / Q000208:ethnology / Q000517:prevention & control*; D022362:Hepatitis A Vaccines; D006801:Humans; D007198:Indians, North American; D007223:Infant; D008297:Male; D015995:Prevalence; D012423:Rural Health; D014761:Viral Hepatitis Vaccines / Q000008:administration & dosage* / Q000009:adverse effects
D022362:Hepatitis A Vaccines; D014761:Viral Hepatitis Vaccines