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Technical Notes for NIS Surveillance Tables

This page provides brief technical notes describing the abbreviations, variables, and estimates in the NIS Surveillance Tables. See a detailed description of the NIS documentation and datasets.

Vaccines

  • 4+DTP refers to 4 or more doses of diphtheria and tetanus toxoids and pertussis vaccine, or diphtheria and tetanus toxoids vaccine or diphtheria, tetanus toxoids, and acellular pertussis vaccine (DTP/DT/DTaP).
  • 3+polio refers to 3 or more doses of poliovirus vaccine.
  • 1+MCV refers to 1 or more doses of measles-containing vaccine, including MMR.
  • 1+MMR refers to 1 or more doses of measles-mumps-rubella vaccine.
  • 3+Hib refers to 3 or more doses of Haemophilus influenzae type b (Hib) vaccine.
  • Hib-PS refers to the primary series of Hib (2 or 3 doses, depending on product type received).
  • Hib-FS refers to the full series of Hib (3 or 4 doses, depending on product type received).
  • 3+HepB refers to 3 or more doses of hepatitis B vaccine.
  • 1+Var refers to 1 or more doses of varicella vaccine received at or after age 12 months, unadjusted for history of varicella illness.
  • 3+PCV refers to 3 or more doses of pneumococcal conjugate vaccine.
  • 4+PCV refers to 4 or more doses of pneumococcal conjugate vaccine.
  • 1+HepA refers to 1 or more doses of hepatitis A vaccine.
  • 2+HepA refers to 2 or more doses of hepatitis A vaccine.
  • Rotavirus refers to 2 or 3 (or more) doses of rotavirus vaccine, depending on product type received.
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Series

  • 3:3:1 refers to 3 or more doses of DTP/DT/DTaP, 3 or more doses of poliovirus vaccine, and 1 or more doses of MCV.
  • 3-Vaccine Series (4:3:1) refers to 4 or more doses of DTP/DT/DTaP, 3 or more doses of poliovirus vaccine, and 1 or more doses of MCV.
  • 4:3:1:3 refers to 4:3:1 and 3 or more doses of Hib.
  • 4:3:1:3:3 refers to 4:3:1:3 and 3 or more doses of Hep B.
  • 4:3:1:3:3:1 refers to 4:3:1:3:3 and 1 or more doses of varicella.
  • 4:3:1:3:3:1:4 refers to 4:3:1:3:3:1 and 4 or more doses of PCV.
  • 4-Vaccine Series (4:3:1:3*) refers to 4:3:1 and the full series of Hib (3 or 4 doses, depending on product type received).
  • 5-Vaccine Series (4:3:1:3*:3) refers to 4:3:1:3* and 3 or more doses of Hep B.
  • 6-Vaccine Series (4:3:1:3*:3:1) refers to 4:3:1:3*:3 and 1 or more doses of varicella.
  • 7-Vaccine Series (4:3:1:3*:3:1:4) refers to 4:3:1:3*:3:1 and 4 or more doses of PCV.
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Age

Annual NIS:

Starting in the 2011 data collection year, children were age eligible to be included in the survey if they were born from January, three years prior to the start of the survey, through May, one year prior to the start of the survey. For example, children in the survey period from January through December, 2011 were born from January 2008 through May 2010.

Prior to the 2011 data collection year, children were age eligible to be included in the survey if they were born from February, three years prior to the start of the survey, through May, one year prior to the start of the survey. For example, children in the survey period from January through December, 2010 were born from February 2007 through May 2009.

Mid-Year NIS:

Starting with the 2011-2012 mid-year reporting period, children were age eligible to be included in the report if they were born from July, three years prior to the report, through November, and one year prior to the report. For example, children included in the report from July 2011 through June 2012 were born from July 2008 through November 2010.

Prior to the 2011 data collection year, children were age eligible to be included in the mid-year survey reporting period if they were born from August, three years prior to the report, through November one year prior to the report. For example, children included in the report from July 2009 through June 2010 were born from August 2006 through November 2008.

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Race and Ethnicity

Child’s race/ethnicity was reported by his/her parent or guardian. Children identified as white, black, Asian, Native Hawaiian/other Pacific Islander, or American Indian/Alaska Native are non-Hispanic. Children identified as multiracial had more than one race category selected. Persons identified as Hispanic might be of any race.

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Vaccination Coverage

The coverage among 19 to 35 month-olds reflects immunization practices and programs that were in place for months to more than 2 years before the survey was conducted. Given the length of time required to produce and publish results, these published results may reflect immunization practices 2 to 4 years in the past.

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National Coverage Estimates

The entire NIS survey sample contains approximately 25,000 completed household interviews. National coverage estimates are based on the subsample of approximately 15,000 children with adequate provider data. National vaccination coverage estimates have much smaller (less than ± 1%) confidence intervals and are much more precise than state or urban area estimates.

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Sample Size Estimates

Estimates are listed as NA (Not Available) if the sample size in a subgroup was not sufficiently large to meet the NCHS standard of reliability or precision: 1) if the unweighted sample size for the denominator was less than 30; 2) if the (CI half width)/Estimate was greater than 0.588; or 3) if the CI half width was greater than 10. In these cases the estimate for that subgroup is not reported, but the individuals are still included in the overall sample and may have an effect on the overall estimate.

An area's vaccination coverage estimate is based on the provider-verified responses for children who live in households with landline and cell telephones. Complex statistical methods are used to adjust for children whose parents refuse to participate, those who live in households without landline and cell telephones, or those whose immunization histories cannot be verified through their providers.

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Confidence Intervals (CI)

CI refers to a 95% confidence interval. The 95% confidence intervals around the coverage estimates are measures of precision; wide confidence intervals are a sign of a relatively small sample size and relatively less precision. Consequently, looking at an area's data over time is valuable for a correct understanding of apparent changes in coverage. Where confidence intervals overlap, the observed difference between estimates might be due to chance.

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