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RESEARCH AND PRACTICE |
At the time of the study, all of the authors were with the National Immunization Program, Centers for Disease Control and Prevention, Atlanta, Ga.
Correspondence: Requests for reprints should be sent to Shannon Stokley, MPH, National Immunization Program, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, Mail Stop E-52, Atlanta, GA 30333 (e-mail: sstokley{at}cdc.gov).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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Objective. We examined heptavalent pneumococcal conjugate vaccine (PCV7) uptake among children aged 19 to 35 months in the United States and determined how uptake rates differed by state vaccine financing policy.
Methods. We analyzed data from the 2001–2003 National Immunization Survey. States that changed their vaccine financing policy between 2001 and 2003 (n=17) were excluded from analysis. Logistic regression was performed to identify the association between state vaccine financing policy and receipt of 3 or more doses of PCV7 after control for demographic characteristics.
Results. The proportion of children receiving 3 or more doses increased from 6.7% in 2001 to 69.0% in 2003. After controlling for demographic characteristics, children residing in states that provided all vaccines except PCV7 to all children had lower odds of receiving 3 or more doses compared to children residing in states that provided PCV7 only to children eligible for the Vaccines for Children program (odds ratio=0.58; 95% confidence interval=0.51, 0.66).
Conclusion. It is essential that we continue to monitor the effect that state vaccine financing policy has on the delivery of PCV7 and future vaccines, which are likely to be increasingly expensive.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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Studies conducted soon after vaccine licensure showed that more than 80% of physicians had adopted the ACIP recommendations for PCV7.6,7 As with other new vaccines,8 the vaccine was not incorporated into routine practice policy uniformly across physician types; more than 90% of pediatricians were offering the vaccine to their patients compared to only 55% to 68% of family physicians.6,7 Although the majority of physicians were offering the vaccine to their patients, 2 obstacles stood in the way of a seamless transition from vaccine licensure to vaccine administration: the cost of the vaccine and difficulties sustaining an adequate supply to meet consumer demand.
PCV7 is currently the second most expensive vaccine included in the routine childhood vaccination schedule; as of March 2006, 1 dose of PCV7 cost $54.12 if purchased via federal contracts or $65.95 if purchased privately.9 By contrast, the cost of other vaccines included in the routine childhood vaccination schedule purchased through federal contracts ranges from $7.66 per dose (Haemophilus influenzae type b) to $74.85 per dose (measles, mumps, rubella, and varicella).9 Initially, there was a delay in insurance carriers’ adding PCV7 to their benefit packages, and some insured patients had to pay out-of-pocket costs for the vaccine. Consequently, many physicians reported referring patients without adequate coverage for PCV7 to health departments.10
Moreover, states’ vaccine financing policies differ, which may make it difficult for some children to receive PCV7. All states receive funds to purchase vaccines for children eligible for the Vaccines for Children (VFC) program, which was developed to eliminate cost as a barrier to receiving vaccines. To be eligible for VFC, children must be enrolled in Medicaid, uninsured, of American Indian/Alaska Native descent, or underinsured but receiving vaccines at a federally qualified health center. States have the option of using other federal and state funds to purchase additional vaccines for children not eligible for VFC as a way to enhance their VFC program. However, some states that have chosen to enhance their VFC program have excluded PCV7 from their policy because of the cost of the vaccine.
Since PCV7 was licensed for use, the United States has experienced 2 severe shortages of the vaccine.11,12 The first shortage occurred between August 2001 and May 2003 and the second between November 2003 and September 2004. During both shortages, the ACIP released interim recommendations to providers to suspend the administration of the third and fourth doses of the series.13–15 The shortages occurred in all states independent of region16,17 and, thus, independent of state vaccine financing policy. The timing and duration of these shortages, particularly the first, have obvious implications for vaccine uptake.
We examined uptake of PCV7 among children aged 19 to 35 months residing in the United States and analyzed how uptake rates differed by state vaccine financing policy. Our primary hypothesis was that children residing in states that excluded PCV7 from their financing policy would be less likely to receive 3 or more doses of the vaccine compared with children living in states with a policy that included PCV7.
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METHODS |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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We analyzed NIS data collected from 2001, when PCV7 was first added to the survey, through 2003, the most recent year of available data (response rates based on the Council of American Survey Research Organizations methodology=76.1% in 2001, 74.2% in 2002, 69.7% in 2003). Analysis of NIS data was based on children in households interviewed with adequate vaccination history from their vaccination provider(s) (70.4% of respondents in 2001, 67.3% in 2002, 68.6% in 2003). In 2001, 2002, and 2003, provider-verified data were collected, respectively, from 23 642 children (born between January 1998 and June 2000), 21410 children (born between January 1999 and June 2001), and 21310 children (born between January 2000 and July 2002). Although some children included in the analytic sample were not eligible to receive 3 or more doses of PCV7 because they were 12 or more months old when the vaccine became licensed, all children were eligible to receive at least 1 dose of vaccine after licensure. Because this study focuses on delivery of vaccine and not protection against pneumococcal disease, we included all children in the analyses.
State (and, in some cases, city) vaccine financing policy was self-reported by the state immunization program to the National Immunization Program. With the exception of San Antonio, metropolitan areas had the same policy as their state. For 16 states (Arkansas, California, Delaware, Hawaii, Kansas, Kentucky, Missouri, Montana, North Carolina, North Dakota, Oklahoma, Texas [excluding San Antonio], Utah, Virginia, West Virginia, Wyoming) and the District of Columbia, the vaccine financing policy changed between 2001 and 2003; we excluded these states from our analysis. The included states and cities were defined by their vaccine financing category as follows:22
VFC Only.
Immunization program supplies only VFC vaccines to all VFC-enrolled providers. However, public health department clinics may provide any vaccine to any child who presents for vaccination (Alabama, Colorado, Indiana, Iowa, Louisiana, Mississippi, Nebraska, New Jersey, Ohio, Oregon, Pennsylvania, Tennessee, Wisconsin).
VFC and Underinsured.
Immunization program supplies all VFC-enrolled providers with all vaccines for children who are eligible for VFC or who are underinsured (i.e., whose insurance does not cover the cost of the vaccine) (Arizona, Florida, Georgia, Maryland, Michigan, Minnesota, New York, South Carolina, San Antonio).
VFC and Underinsured—Select.
Immunization program supplies all VFC-enrolled providers with all vaccines for VFC-eligible children and all vaccines except PCV7 for underinsured children (Illinois).
Universal.
Immunization program supplies all vaccines to all providers for all children (Alaska, Idaho, Massachusetts, Maine, New Hampshire, New Mexico, Rhode Island, Washington).
Universal—Select.
Immunization program supplies all vaccines except PCV7 to all providers for all children. PCV7 is supplied only to VFC-enrolled providers for VFC-eligible children (Connecticut, Nevada, South Dakota, Vermont).
Statistical analysis included estimating the proportion of children receiving PCV7 by dose number and survey year. To evaluate the association between state vaccine financing policy and receipt of 3 or more doses of vaccine, we conducted bivariate and multivariate analyses. The bivariate analysis compared the following vaccine financing policies: Universal versus Universal—Select and VFC and Underinsured versus VFC and Underinsured—Select. In the multivariate logistic regression analysis, which controlled for characteristics of the child, mother, and provider, we evaluated state vaccine financing policies as a single categorical variable, with VFC-Only financing policy as the referent. In addition, we assessed for potential 2-way interactions among independent variables in the multivariate model. Variables included child’s year of birth, race/ethnicity, and status as first-born; maternal educational level, marital status, and age at delivery; poverty status; living in a metropolitan statistical area (MSA); previous receipt of varicella vaccine; vaccination provider’s enrollment in the VFC program; type of facility administering the vaccine; and state vaccine financing policy. MSA status was determined by respondents’ telephone area code and exchange.23
All estimates and 95% confidence intervals (CIs) were calculated using SAS release 8.02 (SAS Institute Inc, Cary, NC) and SAS-callable SUDAAN release 8.0.0 (Research Triangle Institute, Research Triangle Park, NC).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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). The overall proportion of children receiving 1 dose increased from 37.3% (95% CI=36.2%, 38.4%) in 2001 to 88.5% (95% CI=87.7%, 89.2%) in 2003. Moreover, the proportion of children receiving 3 doses increased from 6.7% (95% CI=6.2%, 7.3%) in 2001 to 69.0% (95% CI=67.8%, 70.1%) in 2003.
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The unadjusted and adjusted ORs describing the relation between receipt of 3 or more doses of PCV7 and the independent variables are shown in Table 1. Unadjusted and adjusted ORs predicting receipt of 1 or more doses of PCV7 were similar to those for 3 or more doses but tended to be closer to 1.0 (results not shown). The interaction of poverty status and state vaccine financing policy was significant, as was that of type of facility and state vaccine financing policy; however, including the interaction terms in the model did not change the direction of the findings and only slightly changed the magnitude of the main effects. Because the interaction terms had little substantive public health impact, we excluded them from the final multivariate model for the sake of simplicity. The interaction between receiving vaccines from at least 1 VFC-enrolled provider and state vaccine financing policy was not significant (P=.69). Finally, marital status and receiving vaccines from at least 1 VFC-enrolled provider were found to be not significant in the multivariate model and were excluded from the final model.
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). In the unadjusted analysis, children residing in a Universal state had significantly higher odds of receiving 3 or more doses of PCV7 than children residing in a VFC-Only state. Residing in a state with a Universal policy was no longer significant after adjusting for other child and maternal characteristics. Residing in a state with a Universal—Select or a VFC and Underinsured policy remained significant in the multivariate analysis. Children residing in these states had lower odds of receiving 3 or more doses of PCV7 than children residing in a VFC-Only state.
Type of facility also was associated with receipt of 3 or more doses of PCV7 (Table 1). Children who received vaccines at private facilities or at a mixture of public and private facilities had significantly higher odds of receiving 3 or more doses of PCV7 than those vaccinated at all public facilities. This finding remained significant after adjusting for other factors in the multivariate analysis. Children who received vaccines from multiple providers had lower odds of receiving 3 or more doses of PCV7 compared with children who were vaccinated by a single provider.
Finally, child characteristics associated with receiving 3 or more doses of PCV7 included being of a race/ethnicity other than Black, non-Hispanic; being first born; living in a household above the poverty level; living in an MSA; and previous receipt of varicella vaccine. Significant maternal characteristics included having a college education.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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Children residing in a Universal—Select state were significantly less likely to receive 3 doses of PCV7 compared with children living in a Universal state (in unadjusted analysis) or those in a VFC-Only state (in adjusted analysis). The Universal—Select policy involves a decision on the part of the state to not include PCV7 as part of the vaccines routinely supplied to providers for children not eligible for VFC. Thus, underinsured children (i.e., those whose health insurance does not cover PCV7) living in a Universal—Select state are subject to a 2-tiered vaccine distribution system. These children can receive all routinely recommended vaccines—such as the diphtheria and tetanus toxoids and acellular pertussis vaccine—from their primary care provider but must pay out-of-pocket for PCV7 or go to a federally qualified health center or public health department clinic to receive public-purchased PCV7. This creates a disruption in service delivery and may be a barrier to vaccination.
One of the main reasons states choose to become a "Select" state is vaccine cost. To provide vaccines to children who are not eligible for the VFC program, states use federal grant funds and other state and local funds to purchase vaccines at the federal contract price. Since federal funds have not kept pace with the cost of new vaccines in recent years,24 states must make decisions regarding which vaccines to fund. Between 2000 and 2003, 4 states (Montana, Texas, Virginia, Wyoming) changed their vaccine financing policy to exclude PCV7. Further evaluation of states’ adopting and implementing a "Select" policy is needed to understand how, over time, these policies affect receipt of the vaccines excluded from the policy.
The results from the multivariate analysis regarding the Universal and the VFC and Underinsured policies were surprising. Both of these policies are considered enhancements to the VFC program by providing routine vaccines to additional children not eligible for VFC benefits. Yet, children residing in states with a VFC and Underinsured policy were less likely to receive 3 or more doses of PCV7 than children living in a VFC-Only state. The association between residing in a Universal state and receiving 3 or more doses of PCV7 was not significantly different from that for residing in a VFC-Only state in the adjusted analysis.
The reasons for these results are unclear. Perhaps there is low provider awareness of eligibility for state-supplied vaccines in these states, particularly regarding the PCV7 vaccine. A physician survey by Davis et al. found that 22% of physicians practicing in a Universal state and 30% practicing in a VFC enhanced state (e.g., VFC and Underinsured) would refer a child to a public health department clinic if the child’s health insurance did not cover PCV7.10 Further evaluation is needed to understand how physicians learn about and interpret their state vaccine financing policy.
Child and maternal demographic variables associated with receipt of PCV7 were consistent with factors associated with receipt of other routinely recommended vaccines.25–30 Multivariate logistic regression analysis indicated that higher maternal educational level, being first born, living above poverty, living in an MSA, receiving vaccines from a single provider, and being of a race/ethnicity other than Black, non-Hispanic were significantly associated with receipt of 3 or more doses of PCV7. Although the association between race/ethnicity and receipt of routinely recommended vaccines has been observed in many studies,25,26,30 it is especially troubling for PCV7 because Black children have relatively high incidence rates of pneumococcal disease.1 A 2004 study showed that the introduction of PCV7 has reduced the disparity in pneumococcal disease incidence among Whites and Blacks,4 and further efforts are needed to eliminate disparities between children according to race and ethnicity.
The multivariate analysis also indicated that children who had received the varicella vaccine were more likely to receive 3 or more doses of PCV7. Varicella was added to the routine childhood vaccination schedule in 1995 and was met with resistance from both health care providers and parents.31–33 The positive association between receipt of varicella and receipt of PCV7 may be an indication of parents and providers who are more accepting of new vaccines in general.
This study is subject to several limitations. First, there are potential biases with the data inherent to the NIS study design. The NIS is a telephone survey and relies on provider participation. Although statistical adjustments are made for nontelephone households, number of voice-line telephones in the household, provider response propensity, and a variety of other factors, some bias probably remains. In addition, the NIS data are weighted to represent the children in each birth cohort. When more than 1 year of data are combined, we may double- or triple-count some children because the birth cohorts overlap across survey years. This introduces a bias in the multivariate analysis toward children who were born near the middle of the period of eligibility. This bias is partially, but not totally, accounted for by including year of birth in the multivariate model and is not believed to impact our qualitative conclusions of the data.
Second, 16% of the analytic sample were not eligible to receive 3 or more doses of PCV7 because they were 12 or more months old when the vaccine became licensed. We controlled for year of birth in our multivariate model, predicting receipt of 3 or more doses in order to adjust for the association between year of birth and likelihood of being vaccinated. In addition, the multivariate model predicting receipt of 1 or more doses of PCV7 (which all children were eligible to receive) yielded similar results as the model predicting receipt of 3 or more doses. Therefore, we believe including these children in the analysis did not bias our results. Conducting an age-appropriate analysis of the children eligible for vaccination is warranted and would provide useful information regarding protection against pneumococcal disease.
Third, our results are not nationally representative, given that we excluded 16 states and the District of Columbia because their vaccine financing policy changed during the study period. Further study is warranted to determine the effect that changing policies—as well as physician knowledge of and ability to implement the current financing policy in their state—has had on receipt of PCV7 and other vaccines. Our analysis provides an initial review of factors associated with receiving 3 or more doses of PCV7. However, further analysis should be conducted with future NIS survey years (when all children surveyed are eligible, agewise, to receive the complete series) to better understand factors associated with vaccination.
Finally, our analysis did not adjust for the vaccine shortage that occurred when many of the children included in the NIS were eligible to receive PCV7. We did not collect information from the vaccination providers about the extent of the PCV7 shortage in their practice or their adherence to the ACIP interim recommendations. In addition, because the shortages occurred soon after introduction of the vaccine, there is no reliable baseline estimate of vaccine coverage to evaluate the impact of the shortage. Results from our study indicate a steady increase over time in the proportion of children initiating the PCV7 series. Despite the shortage, providers were clearly making a concerted effort to start the series.
Uptake of PCV7 has been more rapid than that of other vaccines recently introduced to the routine childhood immunization schedule. For example, 4 years after hepatitis B vaccine was licensed, coverage for 3 or more doses reached 68%,34 and coverage for 1 dose of varicella did not reach 68% until 5 years after licensure.35 The rapid uptake of PCV7 may be largely because of physician support of the vaccine. A physician survey conducted by Schaffer et al. shortly after the ACIP released its recommendation for the vaccine found that 90% of respondents recommended the vaccine either strongly or moderately strongly for patients under age 12 months.6 Furthermore, the study found that the majority of physicians rated PCV7 as being as or more important compared with each of the other routinely recommended vaccines for children.6
The initial experience with PCV7 and state vaccine financing policies highlights a problem that may become more familiar in the future as additional vaccines become recommended for routine use. The 2000 Institute of Medicine report Calling the Shots: Immunization Finance Policies and Practices reported that the number of vaccines licensed and universally recommended for all children will triple by the year 2020.36 It has been estimated that the cost to vaccinate a child, under the federal contract price, will increase from $385 in 2001 to $1225 in 2020.37 The new vaccines are likely to be increasingly expensive and may prompt more states to adopt "Select" vaccine financing policies. Our findings of lower coverage in Universal–Select states for excluded vaccines indicate the necessity of monitoring the effect that a state’s vaccine financing policy has on the delivery of PCV7 and future vaccines.
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Acknowledgments |
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Human Participant Protection
The National Immunization Survey has been approved by the institutional review board of the Centers for Disease Control and Prevention.
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Footnotes |
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Contributors
S. Stokley conceptualized the study and supervised all aspects of its implementation. K. M. Shaw assisted with the study and completed the analyses. L. Barker provided statistical expertise and assisted with the analyses. J. M. Santoli and A. Shefer assisted with the study and provided expertise with interpreting state vaccine financing policies. All authors helped to conceptualize ideas, interpret findings, and review drafts.
Accepted for publication September 17, 2005.
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References |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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2. Black S, Shinefield H, Fireman B, et al. Efficacy, safety and immunogenicity of heptavalent pneumococcal conjugate vaccine in children. Northern California Kaiser Permanente Vaccine Study Center Group. Pediatr Infect Dis J. 2000;19:187–195.[CrossRef][ISI][Medline]
3. Black SB, Shinefield HR, Ling S, et al. Effectiveness of heptavalent pneumococcal conjugate vaccine in children younger than five years of age for prevention of pneumonia. Pediatr Infect Dis J. 2002;21:810–815.[CrossRef][ISI][Medline]
4. Flannery B, Schrag S, Bennett NM, et al. Impact of childhood vaccination on racial disparities in invasive Streptococcus pneumoniae infections. JAMA. 2004; 291:2197–2203.
5. Ramani RR, Hall WN, Boulton M, Johnson DR, Zhu BP. Impact of PCV7 on invasive pneumococcal disease among children younger than 5 years: a population-based study. Am J Public Health. 2004; 94:958–959.
6. Schaffer SJ, Szilagyi PG, Shone LP, et al. Physician perspectives regarding pneumococcal conjugate vaccine. Pediatrics. 2002;110:e68.
7. Davis MM, Ndiaye SM, Freed GL, Clark SJ. One-year uptake of pneumococcal conjugate vaccine: a national survey of family physicians and pediatricians. J Am Board Fam Pract. 2003;16:363–371.[Medline]
8. Freed GL, Bordley WC, Clark SJ, Konrad TR. Universal hepatitis B immunization of infants: reactions of pediatricians and family physicians over time. Pediatrics. 1994;93:747–751.
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11. Centers for Disease Control and Prevention. Notice to readers: decreased availability of pneumococcal conjugate vaccine. MMWR Morb Mortal Wkly Rep. 2001;50:783–784.
12. Petkus D. Wyeth experiencing temporary interruption in Prevnar shipments [press release]. Wyeth Pharmaceuticals; November 6, 2003. Available at: http://www.wyeth.com/news/Pressed_and_Released/pr11_06_2003_09_28_11.asp. Accessed April 2, 2006.
13. Centers for Disease Control and Prevention. Notice to readers: updated recommendations on the use of pneumococcal conjugate vaccine in a setting of vaccine shortage—Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep. 2001;50: 1140–1142.
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15. Centers for Disease Control and Prevention. Notice to readers: updated recommendations on the use of pneumococcal conjugate vaccine: suspension of recommendation for third and fourth dose. MMWR Morb Mortal Wkly Rep. 2004;53:177–178.[Medline]
16. Freed GL, Davis MM, Clark SJ. Variation in public and private supply of pneumococcal conjugate vaccine during a shortage. JAMA. 2003;289:575–578.
17. Stokley S, Santoli JM, Willis B, Kelley V, Vargas-Rosales A, Rodewald LE. Impact of vaccine shortages on immunization programs and providers. Am J Prev Med. 2004;26:15–21.[CrossRef][ISI][Medline]
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31. Schaffer SJ, Bruno S. Varicella immunization practices and the factors that influence them. Arch Pediatr Adolesc Med. 1999;153:357–362.
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| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
