2014-15 NHIS, BRFSS, and NIS-Flu Influenza Data

The National Health Interview Survey (NHIS) is the data source used to monitor Healthy People 2020 objectives for influenza vaccination (IID-12.11-13)External. Influenza vaccination coverage estimates nationally and by state and selected local area from NIS-Flu and BRFSS are available each season approximately eleven months before final national estimates from NHIS. A comparison of national estimates from NIS-Flu and BRFSS to NHIS is available below for the 2014-15 season. Additional information on methods is available at Surveillance of Influenza Vaccination Coverage — United States, 2007–08 Through 2011–12 Influenza Seasons.

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Table 1. Influenza vaccination coverage* by age group and race/ethnicity, children 6 months through 17 years, National Health Interview Survey (NHIS) and National Immunization Survey-Flu (NIS-Flu), United States, 2014-15 influenza season

Total Change from 2013-14|| to 2014-15 influenza season
(percentage points)
White only,
non-Hispanic
Black only,
non-Hispanic
Hispanic Other,
non-Hispanic
Surveillance System Unweighted Sample Size %§ 95% CI % 95% CI % 95% CI§ % 95% CI % 95% CI
NHIS
   Age Group
      6 months-17 years 8,574 53.1 ±2.0 1.3 51.4 ±2.7 50.5 ±4.9 54.2 ±3.3 63.6 ±6.7
      6-23 months 803 66.4 ±6.1 2.9 69.6 ±10.6 51.2 ±16.3 64.9 ±10.2 76.9 ±16.9
      2-4 years 1,449 57.8 ±4.3 0.3 56.1 ±5.5 57.5 ±12.0 57.9 ±9.0 66.8 ±11.6
      5-12 years 3,690 55.4 ±2.7 3.4 54.7 ±3.9 52.8 ±8.4 55.4 ±4.9 64.5 ±7.6
      13-17 years 2,632 41.8 ±3.3 -0.2 38.9 ±4.1 43.2 ±9.0 45.1 ±5.7 51.1 ±15.7
NIS-Flu
   Age Group
      6 months-17 years 128,143 59.3  ±0.8 0.4 56.0 ±0.9 58.3 ±2.5 64.2 ±1.8 66.0 ±2.3
      6-23 months 14,126 74.6  ±1.9 0.3 73.2 ±2.3 68.9 ±6.4 79.0 ±4.4 77.0 ±4.4
      2-4 years 23,500 67.8 ±1.7 -0.3 64.7 ±2.1 68.1 ±5.5 71.1 ±3.9 73.7 ±4.7
      5-12 years 59,075 61.8 ±1.1 0.8 57.9 ±1.3 60.2 ±3.2 68.1 ±2.4 69.0 ±3.3
      13-17 years 31,442 46.6 ±1.4 0.2 44.7 ±1.7 47.2 ±4.3 49.4 ±3.5 51.1 ±4.9
Difference Percent Vaccinated, NIS-Flu -NHIS
   Age Group
      6 months-17 years 6.2 ±2.2 4.6 ±2.8 7.8 ±5.5 10.0 ±3.8 2.4 ±7.1
      6-23 months 8.2 ±6.4 3.6 ±10.8 17.7 ±17.5 14.1 ±11.1 0.1 ±17.5
      2-4 years 10.0 ±4.6 8.6 ±5.9 10.6 ±13.2 13.2 ±9.8 6.9 ±12.5
      5-12 years 6.4 ±2.9 3.2 ±4.1 7.4 ±9.0 12.7 ±5.5 4.5 ±8.3
      13-17 years 4.8 ±3.6 5.8 ±4.4 4.0 ±10.0 4.3 ±6.7 0.0 ±16.4

Abbreviation: CI = Confidence Interval

* Estimates of the percentage of people vaccinated are based on interviews conducted beginning September (NHIS) or October (NIS-Flu) 2014 through June 2015 and reported vaccinations from July 2014 through May 2015.

Race/ethnicity is based on parental report. Persons categorized as white, black, or other were identified as non-Hispanic. Persons identified as Hispanic might be of any race. The other race category includes Asian, American Indian/Alaska Native (AI/AN), and multiple races.

Excludes U.S. territories.

§ Percentage vaccinated. Percentages are weighted to the non-institutionalized, U.S. civilian population. Month of vaccination was imputed for respondents with missing month of vaccination data (n= 622 [11.0%] in NHIS, n= 13,057 [18.9%] in NIS-Flu).

|| Estimates of the percentage of people vaccinated based on interviews conducted September (NHIS) or October (NIS-Flu) 2013 through June 2014 and reported vaccinations from July 2013 through May 2014.

Statistically significant difference between the 2014-15 NIS-Flu and the 2014-15 NHIS season by t-test (p<0.05).

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Table 2. Influenza vaccination coverage* by age group, high-risk status, and race/ethnicity, adults 18 years and older, Behavioral Risk Factor Surveillance System (BRFSS) and National Health Interview Survey (NHIS) United States,§ 2014-15 influenza season

Total Change from 2013-14 to 2014-15 influenza season
(percentage points)
White only,
non-Hispanic
Black only,
non-Hispanic
Hispanic Other,
non-Hispanic
Surveillance System Unweighted Sample Size %|| 95% CI % 95% CI % 95% CI % 95% CI % 95% CI
NHIS
   Age Group
      ≥18 years 29,195 44.6 ±1.0 1.6 48.2 ±1.4 37.7 ±2.5 33.3 ±2.2 47.3 ±3.7
      18-64 years 22,106 37.7 ±1.0 1.2 40.1 ±1.4 33.1 ±2.5 29.9 ±2.2 42.4 ±4.1
      18-64 years at high risk 4,439 46.0 ±2.5 -1.3 47.7 ±3.3 43.6 ±6.1 42.7 ±5.9 40.3 ±9.2
      18-64 years not at high risk 17,621 35.8 ±1.2 1.9 38.4 ±1.6 30.1 ±2.7 27.1 ±2.5 42.7 ±4.3
      18-49 years 14,621 32.6 ±1.4 1.2 34.4 ±1.8 29.4 ±3.1 25.8 ±2.5 39.9 ±4.7
      18-49 years at high risk 2,004 35.8 ±3.3 -1.8 36.8 ±4.5 36.2 ±8.8 33.3 ±7.3 34.2 ±13.3
      18-49 years not at high risk 12,596 32.1 ±1.6 1.8 34.1 ±2.0 28.3 ±3.3 24.6 ±2.7 40.5 ±4.9
      50-64 years 7,485 48.7 ±2.2 1.0 50.2 ±2.5 41.9 ±4.7 44.9 ±7.1 50.0 ±8.4
      ≥65 years 7,089 73.5 ±1.8 2.0 75.1 ±2.0 64.4 ±6.3 64.1 ±6.3 81.5 ±9.0
BRFSS
   Age Group
      ≥18 years 323,215 43.6 ±0.4 1.4 46.7 ±0.6 38.7 ±1.6 35.0 ±1.8 41.3 ±2.2
      18-64 years 208,124 38.0 ±0.6 1.3 40.0 ±0.6 35.1 ±1.8 32.5 ±2.0 38.2 ±2.4
      18-64 years at high risk 53,795 47.6 ±1.2 1.3 48.5 ±1.2 46.0 ±3.5 45.2 ±4.7 46.8 ±5.1
      18-64 years not at high risk 152,107 35.3 ±0.6 1.4 37.6 ±0.6 31.0 ±1.8 29.8 ±2.2 36.2 ±2.7
      18-49 years 105,619 33.5 ±0.8 1.2 35.1 ±0.8 30.6 ±2.0 29.9 ±2.2 35.6 ±2.7
      18-49 years at high risk 18,269 39.3 ±1.8 0.6 39.1 ±2.0 40.4 ±5.1 38.5 ±5.7 39.3 ±6.1
      18-49 years not at high risk 86,101 32.6 ±0.8 1.5 34.5 ±0.8 28.1 ±2.2 28.8 ±2.4 35.0 ±3.1
      50-64 years 102,505 47.0 ±0.8 1.7 47.7 ±0.8 45.2 ±2.9 42.6 ±4.3 48.1 ±4.9
      ≥65 years 115,091 66.7 ±0.8 1.7 67.5 ±0.8 59.8 ±2.9 65.3 ±4.7 68.2 ±4.3
Difference in percent vaccinated, BRFSS – NHIS
   Age Group
      ≥18 years -1.0 ±1.1 -1.5 ±1.5 1.0 ±3.0 1.7 ±2.8 -6.0** ±4.3
      18-64 years 0.3 ±1.2 -0.1 ±1.5 2.0 ±3.1 2.6 ±3.0 -4.2 ±4.8
      18-64 years at high risk 1.6 ±2.8 0.8 ±3.5 2.4 ±7.0 2.5 ±7.5 6.5 ±10.5
      18-64 years not at high risk -0.5 ±1.3 -0.8 ±1.7 0.9 ±3.2 2.7 ±3.3 -6.5** ±5.1
      18-49 years 0.9 ±1.6 0.7 ±2.0 1.2 ±3.7 4.1** ±3.3 -4.3 ±5.4
      18-49 years at high risk 3.5 ±3.8 2.3 ±4.9 4.2 ±10.2 5.2 ±9.3 5.1 ±14.6
      18-49 years not at high risk 0.5 ±1.8 0.4 ±2.2 -0.2 ±4.0 4.2** ±3.6 -5.5 ±5.8
      50-64 years -1.7 ±2.3 -2.5 ±2.6 3.3 ±5.5 -2.3 ±8.3 -1.9 ±9.7
      ≥65 years -6.8** ±2.0 -7.6** ±2.2 -4.6 ±6.9 1.2 ±7.9 -13.3** ±10.0

Abbreviation: CI = Confidence Interval

* Estimates of the percentage of people vaccinated are based on interviews conducted beginning September 2014 through June 2015 and reported vaccinations from July 2014 through May 2015.

High-risk definition based on the NHIS: adults categorized as at high risk for influenza-related complications self-reported one or more of the following: (1) ever being told by a physician they had diabetes, emphysema, chronic obstructive pulmonary disease, coronary heart disease, angina, heart attack, or other heart condition; (2) having a diagnosis of cancer during the preceding 12 months (excluding nonmelanoma skin cancer) or ever being told by a physician they have lymphoma, leukemia, or blood cancer during the previous 12 months; (3) being told by a physician they have chronic bronchitis or weak or failing kidneys; or (4) reporting an asthma episode or attack during the preceding 12 months. High-risk definition based on the BRFSS: adults categorized as at high risk for influenza-related complications self-reported diabetes, asthma, myocardial infarction, coronary heart disease, chronic obstructive pulmonary disease (COPD), or cancer (excluding skin cancer).

Race/ethnicity is based on self report. Persons categorized as white, black, or other were identified as non-Hispanic. Persons identified as Hispanic might be of any race. The other race category includes Asian, American Indian/Alaska Native (AI/AN), and multiple races.

§ Excludes U.S. territories.

|| Percentage vaccinated. Percentages are weighted to the non-institutionalized, U.S. population. Month of vaccination was imputed for respondents with missing month of vaccination data (n= 520 [3.5%] in NHIS, n= 9,892 [6.3%] in BRFSS).

Estimates of the percentage of people vaccinated based on interviews conducted September 2013 through June 2014 and reported vaccinations from July 2013 through May 2014.

** Statistically significant difference between the 2014-15 BRFSS and the 2014-15 NHIS season by t-test (p<0.05).

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