Assessment of Undervaccinated Children Following a Mass Vaccination Campaign -- Kansas, 1993

A 1992 retrospective survey by the Kansas Department of Health and Environment (KDHE) of children entering school in Kansas indicated that 52% were completely vaccinated by 24 months of age (i.e., received four doses of diphtheria and tetanus toxoids and pertussis vaccine {DTP}, three doses of poliomyelitis vaccine, and one dose of measles-mumps-rubella vaccine {MMR}). In response to this low vaccination coverage rate, the KDHE set a goal for 1995 of completely vaccinating 90% of children by age 24 months. A major new initiative -- Operation Immunize (OI) -- undertaken to accomplish this goal consisted of three statewide vaccination campaigns on weekends during 1993-1994. This report summarizes the results of an assessment of the short-term impact of OI on children who remained undervaccinated following the first campaign.

OI was designed to reach children, particularly those aged less than 24 months, who were not up-to-date with their vaccinations. An extensive promotional effort was made throughout the state to encourage participation in OI. Vaccinations were available free or at reduced cost at 192 sites in the state during the campaigns.

During the first campaign (April 24-25, 1993), 7120 children were vaccinated; 2616 (37%) were aged less than 24 months. Of the children aged less than 24 months, 71% were not up-to-date with their vaccinations; 29% were due for their next series of vaccinations but were not yet considered behind schedule. OI reached 6% of the estimated 31,498 children (based on the 1992 retrospective survey) aged less than 24 months in Kansas who were not up-to-date.

A follow-up study begun in November 1993 assessed the vaccination status of children aged less than 24 months who were vaccinated during the April campaign but who needed additional vaccinations to be brought up-to-date during the next 6 months. OI records were available for 331 of these children. Each child's vaccination status was determined as of October 25, 1993 (6 months after the first OI campaign), using the recommendations of the Advisory Committee on Immunization Practices for DTP, polio, and MMR (1). Information on vaccinations was obtained from local health departments, parents, and physicians.

Children were considered up-to-date if they were within 1 month of being age-appropriately vaccinated by October 25, 1993. If the local health department had no record of vaccinations given since April 24-25, 1993, and the child's parents could not be contacted by phone and did not respond to two written requests for information, the child was considered lost to follow-up. As of October 25, 1993, 102 (31%) children were up-to-date; 35 (11%) had received additional vaccinations but remained behind schedule; 102 (31%) had received no additional vaccinations; and 92 (28%) were lost to follow-up.

Reported by: S Dismuke, MD, Univ of Kansas Medical Center, Kansas City; N McWilliams, Johnson County Health Dept, Mission; S Bowden, M Burt, J Hansen, M Miller, L Perry, A Pelletier, MD, Acting State Epidemiologist, Bur of Disease Control, Kansas Dept of Health and Environment. Div of Field Epidemiology, Epidemiology Program Office, CDC.

Editorial Note

Editorial Note: Mass vaccination campaigns have been successful in developing countries (2-4); however, during the past decade, mass campaigns have not been used widely in the United States. Mass campaigns such as OI can focus public attention on the control of vaccine-preventable diseases and increase support for vaccination programs. However, mass campaigns are resource-intensive, and in some cases, increases in vaccination coverage rates have been difficult to sustain (5,6).

Options for the evaluation of OI were limited by the low incidence in Kansas of the vaccine-preventable diseases targeted by OI and the lack of current data on the vaccination status of Kansas children. The only population-based vaccination data available in Kansas are from retrospective surveys of children entering school. When collected, these data are 3-4 years old and therefore are not useful for evaluating the immediate impact of a mass vaccination campaign.

Calculating the limited percentage of the target population reached by OI provided one measure of the campaign's effectiveness; the study also sought to assess the ongoing impact of the campaign on children's vaccination status. This study indicated that many children reached by OI did not maintain up-to-date vaccination status during the 6 months after the campaign.

The experience with OI demonstrates that reaching undervaccinated children with mass campaigns can be difficult, even when the level of effort and commitment are high, as in Kansas. When used, mass campaigns should be an adjunct to ongoing, comprehensive vaccination programs (as outlined in the Childhood Immunization Initiative {7}), which are designed to meet local needs. Such programs for routine vaccination should include efforts to reduce barriers to vaccination, establish vaccination record information systems, improve surveillance, and use vaccination coverage assessments to monitor program performance.

References

1. ACIP. General recommendations on immunization. MMWR 1989;38:205- 14,219-27.

2. CDC. Update: eradication of paralytic poliomyelitis in the Americas. MMWR 1992;41:681-3.

3. CDC. National Immunization Days and status of poliomyelitis eradication -- Philippines, 1993. MMWR 1994;43:6-7,13.

4. Expanded Program on Immunization. Planning principles for accelerated immunization activities. Geneva: World Health Organization, 1985.

5. Jorgenson DM, Zenker P, Quinlisk MP. Effectiveness of a one-day vaccination campaign -- Oklahoma {Abstract}. In: Abstracts of the 41st Annual Conference of the Epidemic Intelligence Service, Atlanta, April 6-10, 1992. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1992.

6. Abdool Karim SS, Abdool Karim Q, Dilraj A, Chamane M. Unsustainability of a measles immunisation campaign -- rise in measles incidence within 2 years of the campaign. S Afr Med J 1993;83:322-3.

7. CDC. Reported vaccine-preventable diseases -- United States, 1993, and the Childhood Immunization Initiative. MMWR 1994;43:57-60.

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