Full and Partial Flu Vaccination Coverage in Young Children, Six Immunization Information System Sentinel Sites, 2013-14 through 2017-18

The Advisory Committee on Immunization Practices (ACIP) recommends all children 6 months through 18 years receive annual influenza (flu) vaccination and children 6 months through 8 years receive two doses in their first vaccination season to achieve adequate immune response (1). Children who previously received flu vaccines may not require two doses in the current season; however, in some circumstances, two doses are still necessary, e.g., when a new strain is added to a flu vaccine. ACIP updates its flu vaccination recommendations each year, and may recommend two doses to children even after their first flu seasons depending on their vaccination histories (2–6).

For this report, the Centers for Disease Control and Prevention (CDC) analyzed data for >2.6 million children aged <9 years from six Immunization Information Systems (IIS) Sentinel Sites for the 2013–14 through 2017–18 flu seasons, which was approximately 10% of the U.S. pediatric population in this age group; data source and methods have been described elsewhere (7). Full and partial flu vaccination coverage among children 6 months through 8 years is presented by age group and flu season.

Key Findings

  • In the 2017–18 flu season, full flu vaccination coverage was 47.2% in the 6–23 month age group, 37.8% in the 2–4 year age group, and 33.5% in the 5–8 year age group.
  • From the 2016–17 to the 2017–18 flu season, full flu vaccination coverage slightly increased in the 2–4 year age group (by 1.1 percentage point) and 5–8 year age group (by 1.5 percentage point), and remained largely unchanged in the 6–23 month age group.
  • From the 2013–14 through 2017–18 flu seasons, flu vaccination coverage of ≥1 dose declined from the 2013-14 season, and remained largely unchanged over the recent four seasons in the 6–23 month age group. Flu vaccination coverage of ≥1 dose showed a slightly but consistently declining trend over the first four seasons in the 2–4 year and 5–8 year age groups, but increased slightly in the most recent season.

Figure 1.

Figure 1: Seasonal Flu Vaccination Coverage in Young Children, by Age Group and Season, Six IIS Sentinel Sites, 2013–2018

Footnote: Census data were used as denominators and IIS data from the six IIS Sentinel Sites were used as numerators. Full vaccination coverage was classified as having received at least the recommended number of flu vaccine doses (one or two), based on ACIP recommendations for that season. Partial vaccination coverage was classified as having received only one flu vaccine dose when recommended to receive two doses.

 

Conclusion

While small increases in full flu vaccination coverage were observed, vaccination coverage among children during the 2017-18 season remains low. In addition to efforts to increase flu vaccination coverage in general (8), efforts are needed to improve two-dose compliance. This includes improving communication messages for providers and parents about the two-dose flu vaccine recommendations. Furthermore, providers are encouraged to submit data to their state IIS to enhance the system and to assess children’s eligibility for two doses, especially for older children who may be perceived not to need two doses.

Additional Flu Vaccination Coverage Estimates

Additional information on flu vaccination coverage for the United States is provided at FluVaxView as interactive maps, figures, and tables.

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Limitations

This analysis is subject to limitations. First, data from six IIS Sentinel Sites might not represent the full U.S. population. Second, incomplete vaccination histories in IIS data may underestimate vaccination coverage and two-dose compliance, especially in older children who visit their physician’s office less frequently and may receive flu vaccination in other places. However, the 4:3:1:3:3:1:4 series vaccination coverage among children aged 19 through 35 months in these Sentinel Sites was <10 percentage points different from the National Immunization Survey (9), which indicates that the potential underestimation is not large.

Authors (and affiliation)

Xia Michelle Lin1, PhD, MSPH; Richard Anderson2, BS, BA; Loren Rodgers1, PhD

1 Immunization Services Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA.

2 Northrop Grumman Corporation, Atlanta, GA.

Related Links

General information about IIS and IIS Sentinel Sites:

General information about flu:

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References/Resources

  1. Centers for Disease Control and Prevention. Prevention and Control of Influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2008. MMWR Recommendations and reports : Morbidity and mortality weekly report Recommendations and reports / Centers for Disease Control. 2008 Aug 8;57(RR07):1-60.
  2. Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines. Recommendations of the Advisory Committee on Immunization Practices–United States, 2013-2014. MMWR Recommendations and reports : Morbidity and mortality weekly report Recommendations and reports / Centers for Disease Control. 2013 Sep 20;62(RR-07):1-43.
  3. Grohskopf LA, Olsen SJ, Sokolow LZ, Bresee JS, Cox NJ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP) — United States, 2014-15 influenza season. MMWR Morbidity and mortality weekly report. 2014 Aug 15;63(32):691-7.
  4. Grohskopf LA, Sokolow LZ, Olsen SJ, Bresee JS, Broder KR, Karron RA. Prevention and Control of Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices, United States, 2015-16 Influenza Season. MMWR Morbidity and mortality weekly report. 2015 Aug 7;64(30):818-25.
  5. Grohskopf LA, Sokolow LZ, Broder KR, Olsen SJ, Karron RA, Jernigan DB, Bresee JS. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2016–17 Influenza Season. MMWR Morbidity and mortality weekly report. 2016 Aug 26;65(5);1–54.
  6. Grohskopf LA, Sokolow LZ, Broder KR, Walter EB, Bresee JS, Fry AM, Jernigan DB. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2017–18 Influenza Season. MMWR Morbidity and mortality weekly report. 2017 Aug 25;66(2);1–20.
  7. Lin X, Fiebelkorn AP, Pabst LJ. Trends in compliance with two-dose influenza vaccine recommendations in children aged 6 months through 8 years, 2010-2015. Vaccine. 2016 Sep 23.
  8. Centers for Disease Control and Prevention. Estimates of Flu Vaccination Coverage among Children — United States, 2017–18 Flu Season, https://www.cdc.gov/flu/fluvaxview/coverage-1718estimates-children.htm. Accessed October 2018.
  9. Centers for Disease Control and Prevention. Immunization Information Systems Annual Report (IISAR) – IIS Interactive Data Query Tool (2016), https://www2a.cdc.gov/nip/registry/IISAR/IISAR_QUERY.asp, accessed October 2018.

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