About Childhood Immunization Rates from NIS and MIIC

Detailed description of the differences between childhood immunization rates from the National Immunization Survey (NIS) and the Minnesota Immunization Information Connection (MIIC). Updated 9/14

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On this page:
Source
Who is assessed?
How are the rates generated?
Are there differences in how vaccine coverage is defined?
How valid are the rates?
How current are the rates?
What other considerations affect interpretation of the rates?
Additional resources

Source

National Immunization Survey (NIS) Minnesota Immunization Information Connection (MIIC)
  • Centers for Disease Control and Prevention (CDC).
  • Minnesota Department of Health (MDH).


Who is assessed?

NIS MIIC
  • A random sample of U.S. children age 19 through 35 months.
  • Sub-analysis available by age, state, some local areas, race/ethnicity, WIC participation status, poverty status, health care provider type, and rural versus urban residence.
  • Minnesota children age 24 through 35 months with 2 or more non-influenza immunizations in the MIIC immunization registry. Beginning in 2014 Minnesota children age 24 through 35 months in the MIIC immunization registry were assessed.
  • Sub-analysis available by county and by other variables as requested and as available.


How are the rates generated?

NIS MIIC
  • Minnesota rates are based on a surveyed sample of approximately 300 Minnesota children age 19 through 35 months.
  • The CDC contacts a random sample of families by phone to ask about their children's vaccination histories and checks this information against providers' vaccination records.
  • Calculations are based on MIIC records of approximately 70,000 Minnesota children age 24 through 35 months, who have 2 or more non-influenza immunizations recorded in MIIC. Beginning in 2014 the calculations are based on MIIC records of approximately 70,000 Minnesota children age 24 through 35 months in MIIC.


Are there differences in how vaccine coverage is defined?

NIS MIIC
There are differences in how the two data sources define coverage with Hib (Haemophilus influenzae type b), varicella (chickenpox), and PCV (pneumococcal conjugate vaccine), as well as with any series that includes these vaccines.
  • The “full series” of Hib vaccine contains either 3 or 4 doses, depending on the vaccine brand.
  • "Complete Hib” coverage can include 2, 3, or 4 doses, depending on the vaccine brand and age at first dose.
  • Varicella coverage is unadjusted for history of disease.
  • Varicella coverage is adjusted to take into account history of disease.
  • A child is considered covered by PCV if he or she has had at least 4 doses.
  • "Complete PCV" coverage can be 2, 3, or 4 doses, depending on age at first dose.
  • Vaccine series definitions incorporate the specifications above.
  • Vaccine series definitions incorporate the specifications above.


How valid are the rates?

NIS MIIC
  • Minnesota rates are based on a surveyed sample of approximately 300 Minnesota children age 19 through 35 months.
  • Each estimate is accompanied by a "confidence interval," indicating 95 percent likelihood that the true rate falls within this range.
  • Accuracy of the NIS coverage estimates is affected by:
    • Survey design,
    • Statistical adjustments used in calculating rates, and
    • Parental and provider knowledge of child vaccination history.
  • Calculations are based on approximately 70,000 Minnesota children age 24 through 35 months with 2 or more non-influenza immunizations in MIIC. Beginning in 2014 the calculations are based on MIIC records of approximately 70,000 Minnesota children age 24 through 35 months in MIIC.
  • MIIC data may underestimate the actual percent of children receiving vaccines because:
    • Health care provider participation in MIIC is voluntary,
    • MIIC may include children who have moved and
    • Cross border-state immunization data exchange is limited to Wisconsin.
  • Although approximately 85-90 percent of Minnesota health care providers routinely submit immunization data to MIIC, not all those who do report every dose of vaccine administered or historical immunization reported by the patient.
  • Also, when a child moves out of Minnesota his or her MIIC record may not be updated and the child would still be included in the denominator used to calculate the proportion of children receiving immunization.
  • Finally, data exchange with border state immunization information systems is currently limited to Wisconsin. Vaccinations received in Wisconsin by Minnesota residents are in MIIC but there is no similar data exchange with North Dakota, South Dakota, or Iowa at this time.


How current are the rates?

NIS MIIC
  • NIS surveys are conducted throughout the calendar year and each year's results are published in the fall of the following year.
  • Rates reflect immunization practices 2 to 4 years in the past.
  • MIIC rates are calculated based on records of children aged 24 through 35 months as of the assessment date. Thirty days are allowed for data entry into the registry.


Additional resources

 

Updated Monday, September 08, 2014 at 02:40PM