Prevention and Control of Influenza, Recommendations of the Advisory Committee on Immunization Practices (ACIP)

Nicole M. Smith, PhD; Joseph S. Bresee, MD; David K. Shay, MD; Timothy M. Uyeki, MD; Nancy J. Cox, PhD; Raymond A. Strikas, MD


Morbidity and Mortality Weekly Report. 2006;55(27):1-41. 

In This Article

Vaccination Coverage Levels

One of the national health objectives for 2010 is to achieve an influenza vaccination coverage level of 90% for persons aged ≥65 years (objective no. 14-29a).[125] Among persons aged ≥65 years, influenza vaccination levels increased from 33% in 1989[126] to 66% in 1999,[127] surpassing the Healthy People 2000 objective of 60%.[128] Vaccination coverage in this group reached the highest levels recorded (68%) during the 1999-00 influenza season. This estimate was made using the percentage of adults reporting influenza vaccination during the previous 12 months in the National Health Interview Survey (NHIS). The NHIS administered during the first and second quarters of each calendar year was used as a proxy measure of influenza vaccination coverage for the previous influenza season.[127] Possible reasons for increases in influenza vaccination levels among persons aged ≥65 years include 1) greater acceptance of preventive medical services by practitioners; 2) increased delivery and administration of vaccine by health-care providers and sources other than physicians; 3) new information regarding influenza vaccine effectiveness, cost-effectiveness, and safety; and 4) initiation of Medicare reimbursement for influenza vaccination in 1993.[8,14,15,101,102,129,130] Since 1997, influenza vaccination levels have increased more slowly, with an average annual percentage increase of 4% from 1988-89 to 1996-97 versus 1% from 1996-97 to 1998-99. In 2000, a substantial delay in influenza vaccine availability and distribution, followed by a less severe delay in 2001 likely contributed to the lack of progress. However, the slowing of the increase in vaccination levels began before 2000 and is not fully understood.

Estimated national influenza vaccine coverage in 2004 among persons aged ≥65 years and 50-64 years was 65% and 36%, respectively, based on 2004 NHIS data ( Table 3 ). The estimated vaccination coverage among adults with high-risk conditions aged 18-49 years and 50-64 years was 26% and 46%, respectively, substantially lower than the Healthy People 2000 and 2010 objective of 60%.[125,128] Continued annual monitoring is needed to determine the effects of vaccine supply delays and shortages, changes in influenza vaccination recommendations and target groups for vaccination, reimbursement rates for vaccine and vaccine administration, and other factors related to vaccination coverage among adults and children. New strategies to improve coverage will be needed to achieve the Healthy People 2010 objective.[21,22]

Reducing racial and ethnic health disparities, including disparities in vaccination coverage, is an overarching national goal.[125] Although estimated influenza vaccination coverage for the 1999-00 season reached the highest levels recorded among older black, Hispanic, and white populations, vaccination levels among blacks and Hispanics continue to lag behind those among whites.[127,131] Estimated vaccination coverage levels based on 2004 NHIS data among persons aged ≥65 years were 67% among non-Hispanic whites, 45% among non-Hispanic blacks, and 55% among Hispanics (CDC, unpublished data, 2006). Among Medicare beneficiaries, unequal access to care might not be the only factor in contributing toward disparity levels in influenza vaccination; other key factors include having patients that actively seek vaccination and providers that recommend vaccination.[132,133]

In 1997 and 1998, vaccination coverage estimates among nursing home residents were 64%-82% and 83%, respectively.[134,135] The Healthy People 2010 goal is to achieve influenza vaccination of 90% among nursing home residents, an increase from the Healthy People 2000 goal of 80%.[125,128]

Reported vaccination levels are low among children at increased risk for influenza complications. One study conducted among patients in health maintenance organizations (HMOs) documented influenza vaccination percentages ranging from 9% to 10% among children with asthma.[136] A 25% vaccination level was reported among children with severe to moderate asthma who attended an allergy and immunology clinic.[137] However, a study conducted in a pediatric clinic demonstrated an increase in the vaccination percentage of children with asthma or reactive airways disease from 5% to 32% after implementing a reminder/recall system.[138] One study documented 79% vaccination coverage among children attending a cystic fibrosis treatment center.[139] According to 2004 National Immunization Survey data, during the second year of the encouragement for vaccination of children aged 6-23 months, 18% received one or more influenza vaccinations and 8.4% received 2 doses if they were previously unvaccinated.[140] A rapid analysis of influenza vaccination coverage levels among members of an HMO in Northern California determined that in 2004-05, the first year of the recommendation for vaccination of children aged 6-23 months, their coverage level reached 57%.[141] Data from the Behavioral Risk Factor Surveillance System (BRFSS) collected in February 2005 indicated a national estimate of 48% vaccination coverage for 1 or more doses among children aged 6-23 months and 35% coverage among children aged 2-17 years who had one or more high-risk medical conditions during the 2004-05 season.[142] Increasing vaccination coverage among persons who have high-risk conditions and are aged <65 years, including children at high risk, is the highest priority for expanding influenza vaccine use. As has been observed for older adults, a physician recommendation for vaccination and the perception that getting a child vaccinated "is a smart idea" were positively associated with likelihood of vaccination of children aged 6-23 months.[143]

Annual vaccination is recommended for health-care workers. Nonetheless, NHIS 2004 survey data indicated a vaccination coverage level of only 42% among health-care workers (CDC, unpublished data, 2006). Vaccination of health-care workers has been associated with reduced work absenteeism[9] and fewer deaths among nursing home patients[144,145] and is a high priority for reducing the effect of influenza in health-care settings and for expanding influenza vaccine use.[146,147]

Limited information is available regarding use of influenza vaccine among pregnant women. Among women aged 18-44 years without diabetes responding to the 2001 BRFSS, those who were pregnant were less likely to report influenza vaccination during the previous 12 months (13.7%) than those women who were not pregnant (16.8%); these differences were statistically significant.[148] Only 13% of pregnant women reported vaccination according to 2004 NHIS data, excluding pregnant women who reported diabetes, heart disease, lung disease, and other selected high-risk conditions (CDC, unpublished data, 2006) ( Table 3 ). These data indicate low compliance with the ACIP recommendations for pregnant women. In a study of influenza vaccine acceptance by pregnant women, 71% who were offered the vaccine chose to be vaccinated.[149] However, a 1999 survey of obstetricians and gynecologists determined that only 39% administered influenza vaccine to obstetric patients, although 86% agreed that pregnant women's risk for influenza-related morbidity and mortality increases during the last two trimesters.[150]

Data indicate that self-report of influenza vaccination among adults, compared with extraction from the medical record, is both a sensitive and specific source of information.[151] Patient self-reports should be accepted as evidence of influenza vaccination in clinical practice.[151] However, information on the validity of parents' reports of pediatric influenza vaccination is not yet available.


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