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Data and Statistics
> Immunization Coverage in the U.S. >
NIS
Technical
Notes for NIS Surveillance Tables
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Children
in the survey period…
|
were born
between |
|
January-December
2002 |
February 1999
and May 2001 |
|
July 2001-June
2002 |
August 1998
and November 2000 |
|
January-December
2001 |
February 1998
and May 2000 |
|
July 2000-June
2001 |
August 1997
and November 1999 |
|
January-December
2000 |
February 1997
and May 1999 |
|
July 1999-June
2000 |
August 1996
and November 1998 |
|
January-December
1999 |
February 1996
and May 1998 |
|
July 1998-June
1999 |
August 1995
and November 1997 |
|
January-December
1998 |
February 1995
and May 1997 |
|
July 1997-June
1998 |
August 1994
and November 1996 |
|
January-December
1997 |
February 1994
and May 1996 |
|
July 1996-June
1997 |
August 1993
and November 1995 |
- The coverage
rate 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. n>Given the length
of time required to produce and publish results,
these published results reflect immunization
practices 2-4 years in the past.
- 4+DTP refers
to 4 or more doses of diphtheria and tetanus
toxoids and pertussis vaccine, or diphtheria
and tetanus toxoids (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 a measles-mumps- rubella
vaccine.
- 3+Hib refers
to 3 or more doses of Haemophilus influenzae
type b (Hib) vaccine.
- 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 three or more doses of pneumococcal conjugate
vaccine.
- 3:3:1 refers
to 3 or more doses of DTP/DT, 3 or more doses
of poliovirus vaccine, and 1 or more doses
of MCV.
- 4:3:1 refers
to 4 or more doses of DTP/DT, 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 and 1 or more doses of
varicella.
- 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. By
definition, approximately 5% of the 95% confidence
intervals (or about 3 states) will fail to
contain the true coverage, that is, the true
rate will fall outside of the interval. Exactly
how many and which confidence intervals in
any given year will fail to contain the true
vaccination coverage are unknown and unknowable,
but could be as few as 0 or as many as 5.
Consequently, looking at an area’s data over
time is also valuable to a correct understanding
of apparent changes in coverage. Where
confidence intervals overlap, the observed
difference might be due to chance.
- Estimate
is listed as NA (Not Available) if the sample
size in that subgroup was not sufficiently
large to meet the NCHS standard of reliability
or precision: if the unweighted sample
size for the numerator was <30 or (CI
half width)/Estimate <0.5 or (CI half
width)>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.
- National
rates are based on the entire survey sample
of more than 30,000 completed interviews.
Consequently, national vaccination coverage
estimates have much smaller (<+
1%) confidence intervals and are much more
precise than state or urban area estimates.
- Race was
self-reported by the respondent. Hispanic
children can be of any race.
- An
area’s vaccination coverage estimate is based
on the provider-verified responses from children
who live in households with telephones.
Complex statistical methods are used to adjust
for children whose parents refuse to participate,
those who live in households without telephones,
or those whose immunization histories cannot
be verified through their providers.
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