Improved Child Immunization Rates
Midyear results from the National Immunization Survey (NIS) indicate that immunization rates for children in King County are continuing to rise. The NIS provides estimates of vaccination coverage among children aged 19-35 months for each of the 50 states and 28 selected urban areas. This report contains data from the last two quarters of 2003 and the first two quarters of 2004 (July 2003 through June 2004).
Statistically significant increases compared to last year can be noted in coverage of 4 doses of DTaP, 3 doses of Hib, 3 doses of Hep B, 1 dose of varicella vaccine, and all of the combined vaccine series. An improved economy and a variety of education efforts by Public Health in collaboration with health care professionals and partnering agencies may have contributed to the increases.
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National Immunization Survey, July 2003-June 2004
Estimated Vaccination Coverage for Selected Vaccines Among Children 19-35 Months of Age
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.
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4:3:1:3*
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4:3:1:3:3**
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1 MMR
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4 DTaP
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1 Varicella
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US
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82.3±0.9
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80.5±0.9
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92.9+0.6
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85.6+0.8
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86.2+0.7
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WA
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81.5±4.1
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76.8±4.4
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92.6+2.9
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85.6+3.8
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73.1+4.6
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King Co.
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87.7±4.7
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84.1±5.2
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96.1+2.3
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92.4+3.9
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82.8+5.2
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* 4 DTaP, 3 Polio, 1 MMR, 3 Hib, **4 DTaP, 3 Polio, 1 MMR, 3 Hib, 3 HepB
The coverage rate for the combined series 4:3:1:3:3 (4 DTaP, 3 Polio, 1 MMR, 3 Hib and 3 Hep B) has increased significantly since 2001 (84.1% vs. 64.7%). Statistically significant increases since 2001 can also be noted in coverage for 4 doses of DTaP (92.4% vs. 76.5%), and 3 doses of Hepatitis B vaccine (92.8% vs. 78.5%). The trend for varicella vaccine coverage shows a steady increase up to 82.8 percent since the introduction of the vaccine in 1995.
When comparing King County rates to the U.S. and Washington State, point estimates for King County are higher. However, the county, state and national rates are considered statistically equivalent due to confidence intervals.
To view NIS data in its entirety visit: www.cdc.gov/nip/coverage/default.htm#NIS.
Healthcare professionals in King County deserve credit for the good results; keep up the good work! A 2004 study published in Pediatrics, listed King County as one of the top eight counties in the U.S. for number of completely unvaccinated children. We also know that approximately 3.6 percent of children enrolled in King County schools are exempt from at least one immunization (nearly all of the exemptions are for philosophical reasons).
There are at least three limitations for using NIS data. First, NIS is a telephone survey; although statistical weights adjust for non-response and households without telephones, some bias may remain. Second, NIS relies on clinician-verified vaccination histories and assumes that coverage among children whose clinicians did not respond is similar to that among children whose providers responded. Finally, estimates for states and urban areas should be interpreted with caution due to small sample size.
