Vaccination Coverage Surveys in County Health Departments -- Kansas, 1993-1994

The objective of the Childhood Immunization Initiative (CII) is to protect all children in the United States by their second birthday against nine vaccine-preventable diseases. Specific objectives for 1994 were to increase coverage levels to at least 85% for the third dose of diphtheria and tetanus toxoids and pertussis vaccine (DTP3) and the first dose of measles, mumps, and rubella vaccine (MMR1); 75% for the third doses of oral poliovirus vaccine (OPV3) and Haemophilus influenzae type b vaccine (Hib3); and 30% for the third dose of hepatitis B vaccine (HepB3) (1). To determine whether county health departments in Kansas had achieved the national vaccination objectives, in 1993 staff from the Kansas Department of Health and Environment (KDHE) began assessing vaccination coverage rates for children aged 2 years served by county health departments in that state. This report presents the results of the first vaccination coverage assessments of all 105 county health departments in Kansas during November 1993-November 1994.

The Clinic Assessment Software Application (CASA), which was developed by CDC to assist in the measurement of vaccination coverage rates (2,3), was used to assess coverage rates of DTP3, MMR1, OPV3, and Hib3 at the second birthday (4). Coverage rates for HepB3 were not assessed because universal hepatitis B vaccination of infants had not been implemented statewide. KDHE staff conducted 104 assessments; CDC conducted one. Most (100 {95%}) assessments were conducted onsite at county health departments; four (4%) were conducted offsite using copies of county health department vaccination records. The assessments reviewed records for all children aged 2 years and excluded those who were documented to have moved or gone elsewhere for health care. Because county health departments are administratively autonomous in Kansas, methods for maintaining vaccination records are not standardized. In health departments maintaining records for all children receiving services at the department for any reason, the assessment targeted all children with a medical record, including those who had never been vaccinated; in health departments maintaining only vaccination records, the assessment was restricted to children who had received at least one vaccination from the health department. Initially, systematic random sampling was done in health departments with greater than or equal to 50 records; during the assessment, this was changed to include only health departments maintaining greater than 200 records (approximately 20% of all health departments). Systematic random sampling ensured the computation of a 95% confidence interval within seven percentage points of the estimated coverage rate (2). All eligible records were assessed in the remaining health departments (3). Overall, the median number of records reviewed in a health department assessment was 86 (range: seven to 284).

Median coverage rates at the second birthday for individual vaccines ranged from 89% for DTP3 to 75% for OPV3 Table_1. The 1994 goal for all four vaccines assessed was met by 35 (33%) of the health departments; 82 (78%) met or surpassed the goal for Hib3, and 41 (39%) met or surpassed the goal for MMR1. None of the goals were met by 17 (16%) health departments. The median size of the birth cohort of 2-year-olds in counties with health departments achieving the four 1994 goals assessed was 51 (range: 24-364), compared with a median of 411 (range: 36-7580) in health departments not achieving any of these objectives. Health departments in which the survey population included all children with a medical record were less likely to meet the objectives than those that included only children who had received at least one vaccination: a survey population consisting of all children with a medical record was assessed in 13 (77%) of the 17 health departments not meeting any of the objectives, while only one (3%) of the 35 health departments that met the four 1994 goals assessed a comparable population.

KDHE provided findings of each assessment to county health department personnel and reviewed possible improvements in recordkeeping and vaccination practices. In addition, health departments were provided lists of children (based on the study sample) whose vaccinations were not up-to-date. Reported by: S Bowden, M Burt, J Calder, DVM, J Hansen, M Mayer, L Perry, MS, G Pezzino, MD, C Schiffelbein, D Silvius, MA, L Wilberschied, MS, Bur of Disease Control, AR Pelletier, MD, Acting State Epidemiologist, Kansas Dept of Health and Environment. Div of Field Epidemiology, Epidemiology Program Office; Program Operations Br, Div of Immunization Svcs, National Immunization Program, CDC.

Editorial Note

Editorial Note: The approach of KDHE illustrates the potential advantages of assessing provider-specific vaccination coverage levels, including objective characteristics of the vaccine provider's recordkeeping and vaccination practices. The use of a computer-based package such as CASA enables completion of the assessment onsite and immediate dissemination to health department staff. Assessments also enable determination of whether vaccination coverage can be improved through simultaneous administration of multiple vaccines and through elimination of missed opportunities by reviewing a child's vaccination status at every visit to the health department and providing vaccinations when appropriate (5).

The coverage estimates in Kansas are subject to at least four limitations. First, these estimates reflect vaccination coverage only for children attending county health departments and cannot be used as countywide, population-based vaccination rates. Second, criteria for determining when to assess a sample of eligible records was changed during the statewide assessment. Third, because of differences in recordkeeping systems, the populations on which the assessments were based varied; therefore, coverage rates for county health departments in Kansas cannot be compared directly. Finally, estimated reported coverage rates may vary from actual coverage rates. Overestimation can occur in health departments where the assessment of vaccination status includes only children who had received at least one vaccination from the health department. These health departments were more likely to have met the four vaccination goals than those where the assessment of vaccination status includes children seen for any reason. In contrast, underestimation can occur when the records either do not document when children move or do not document vaccinations that were obtained from other providers. In Kansas, underestimation may be more common in larger counties because of the numbers of children to be tracked and the numbers of providers of vaccine.

KDHE has developed plans to improve and expand the assessment process to meet future vaccination coverage goals. The national vaccination coverage objectives set by the CII for 1996 are 90% for DTP3, MMR1, OPV3, and HIB3, and 70% for HepB3 (1) at the second birthday. Therefore, beginning in 1995, the scope of the assessments in Kansas was expanded to examine coverage rates for hepatitis B vaccine, reflecting the statewide implementation of universal hepatitis B vaccination of infants. Uniform criteria were developed for determining which children had moved and should no longer be included in the survey population. In addition, KDHE is considering options for standardizing vaccination recordkeeping to ensure comparability and consistency of assessments.

States receiving Immunization Action Plan funds during 1995 are required to assess all public health clinics annually. * To assist with these assessments, CASA software is available at no charge to public and private providers from the National Immunization Program, CDC, telephone (404) 639-8392.

References

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

2. CDC. Guidelines for assessing vaccination levels of the 2-year-old population in a clinic setting. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1992.

3. CDC. Clinic assessment software application (CASA): user's guide. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1994.

4. ACIP. General recommendations on immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1994;43(no. RR-1).

5. CDC. Standards for pediatric immunization practices: recommended by the National Vaccine Advisory Committee -- approved by the U.S. Public Health Service. MMWR 1993;42(no. RR-5).

* Public Law 103-333.

TABLE 1. Percentage of children aged 2 years who had received selected vaccines by
their second birthday in county health departments, national health objective goals,
and percentage of health departments reaching the 1994 goal -- Kansas, November
1993-November 1994 *
=========================================================================================
                                             National goal         Health departments
No. doses/Vaccine           Median   Range      for 1994            reaching 1994 goal
-----------------------------------------------------------------------------------------
>=3 doses of diphtheria
  and tetanus toxoids
  and pertussis vaccine       89%   41%-100%     85%                 69%

One dose of measles-
  mumps-rubella vaccine       82%   37%-100%     85%                 39%

>=3 doses of oral
   poliovirus vaccine         75%   31%-100%     75%                 55%

>=3 doses of Haemophilus
  influenzae type b
  vaccine                     83%   37%-100%     75%                 78%
-----------------------------------------------------------------------------------------
* Percentage of children receiving care at county health
  departments who were vaccinated based on vaccination records.
=========================================================================================

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