Context Immunization rates among low-income families have lagged behind those
for the general community, with several possible barriers cited in the literature.
Objective To evaluate the effect of an initiative aimed at improving immunization
rates among low-income preschool children by imposing a sanction on families
who failed to provide proof of up-to-date immunization status.
Design and Setting Randomized, controlled before-after trial conducted from January 1,
1993, through December 31, 1996, in Muscogee County, Georgia.
Participants A total of 2500 families with children aged 6 years or younger who received
Aid to Families with Dependent Children assistance.
Intervention Families in the intervention group (n=1500) were informed that receipt
of the welfare benefit for any preschool-aged children was contingent on provision
of proof of up-to-date immunization status at the beginning of welfare eligibility
and, subsequently, semiannually or annually. Case families in the control
group (n=1000) were encouraged to immunize their preschool children but were
not informed of any aid sanctions nor did such sanctions apply to them.
Main Outcome Measure Age-appropriate rates of 5 immunizations (measles-mumps-rubella; poliovirus;
diphtheria and tetanus toxoids and pertussis; Haemophilus
influenzae type b; and hepatitis B), based on examination (with family's
written consent) of medical provider records, compared among intervention-group
vs control-group families.
Results There were no significant differences at baseline between intervention
and control families in immunization rates of preschool children. Families
in the intervention group were significantly more likely than families in
the control group to have up-to-date immunization status in all 4 years of
the study for all 5 immunizations (with 3 exceptions). At age 2 years, 72.4%
of children in the intervention group vs 60.6% of those in the control group
achieved vaccine series completion, which included 4 diphtheria and tetanus
toxoids and pertussis, 3 poliovirus, and 1 measles-mumps-rubella (P<.001). Sanctions were implemented only 11 times. There was relatively
little increased burden on the part of families to comply with requirements.
Conclusion In our study, a monetary sanction in a population receiving welfare
benefits stimulated a significant increase in childhood immunization rates,
suggesting that when welfare recipients are given an incentive to keep their
children's immunizations up-to-date, most are able to do so.