Cincinnati pediatricians’ measured and reported immunizing behavior for children during the national shortages of pneumococcal conjugate vaccine
Highlights
► We assessed physicians’ immunizing behavior during pneumococcal vaccine shortages. ► We compared physicians’ reported immunizing behavior with their measured behavior. ► Physicians often overestimated rates of deferring doses during vaccine shortages. ► Deferral rates were impacted by shortage severity.
Introduction
In recent years the United States has experienced significant shortages of childhood vaccines, including Haemophilus influenzae type b (Hib), diphtheria and tetanus toxoids and acellular pertussis (DTaP), measles, mumps, and rubella (MMR), varicella, and pneumococcal vaccines. The 7-valent pneumococcal conjugate vaccine (PCV7) produced by Wyeth and trademarked as Prevnar® was in short supply twice between 2000, the year it was introduced, and 2010, the year a 13-valent pneumococcal conjugate vaccine replaced the pediatric recommendation for PCV7 [1]. The first PCV7 shortage occurred from September, 2001 to May, 2003 [2], [3]. The second shortage occurred eight months later, from February, 2004 to September, 2004 [4], [5]. Currently, the Centers for Disease Control and Prevention (CDC) aims to maintain a six-month supply of all recommended pediatric vaccines [6]. During the shortage periods of 2001–2003 and 2004, a stockpile for PCV7 did not yet exist. In 2006, pediatric vaccine stockpile levels of several childhood vaccines, including PCV7, proposed by the CDC, were shown to be adequate to absorb the effect of a vaccine production interruption lasting no more than six months; in the event that a vaccine production interruption exceeds six months, modifications to vaccination guidelines may be instituted [7].
Based on data suggesting substantial effectiveness of a partial schedule [8], [9], CDC issued recommendations during both shortages to defer the later PCV7 doses (the third dose at 6 months and the fourth dose at 12–15 months) administered to healthy children, in order to continue high coverage with one and two doses for all healthy children and to ensure that high-risk children continued to receive four doses. During the first shortage, CDC issued two sets of different recommendations. The first set of recommendations was issued at the beginning of the shortage, in September of 2001 [3]. At this time, it was recommended that providers defer vaccinations to children greater than two years of age, except those aged two to five years who were at increased risk for pneumococcal disease, and to give highest priority to vaccinating all infants less than 12 months of age and children aged one to five years who were at an increased risk for disease. The second set of recommendations was issued in December of 2001, after the shortage worsened [10]. Recommendations instructed physicians to administer all four doses of PCV7 to high-risk children, and administer doses to healthy children according to an algorithm that took into account the child's age and the practice's PCV7 supply. During the second shortage, recommendations were again issued multiple times: initially, in February of 2004, CDC recommended that fourth doses be temporarily discontinued for healthy children [5]. In March of that same year, the recommendation changed to include deferral of third doses as well [11]. In July 2004, recommendations were issued again to re-instate the third dose but to continue deferring the fourth dose for healthy children [12]. This recommendation remained until the shortage was resolved in September of 2004 [4].
Physician adherence to these recommendations has been studied through a survey to determine the variation between public and private markets in the supply of PCV7 and the nature and extent of the PCV7 shortage at the practice level during the first shortage [13], national surveys during the first [14] and second [15] shortages, and a survey in a local metropolitan area (Greater Cincinnati) that covered both shortages [16]. In addition, an examination of physician immunizing behavior was conducted during the second shortage in one state (Michigan) based on their statewide immunization information system [17]. In the only study that assessed reported behavior for both shortages, compliance with recommendations appeared to improve substantially during the second shortage compared with the first [16].
No prior studies examined actual immunizing behavior during both shortages, nor have they compared reported immunizing behavior with measured immunizing behavior. Because surveys of physicians are often used to assess immunizing behavior, it is important to assess the accuracy of physician reports. In this study, we measured PCV7 immunizing behavior for healthy children during both shortage and non-shortage periods to assess the accuracy of the physicians’ reported immunizing behavior compared to their actual immunizing behavior.
Section snippets
Study design and population
This study was approved by Cincinnati Children's Hospital Medical Center Institutional Review Board (IRB); CDC relied on Cincinnati's IRB for review. From a list of all 59 pediatric practices in Greater Cincinnati's metropolitan area, we randomly selected fourteen practices to participate using probability proportionate to size (PPS) sampling [18], and our target was to complete a total of 3000 chart reviews. We randomly selected charts for review among children who had at least one visit to
Sample characteristics
Of the 3059 charts selected for review, 171 were excluded from analyses because the child had left the practice, resulting in a total of 2888 children included. Among children whose charts were reviewed, data on race and ethnicity was unavailable for the majority (62.1%). Most children (77.7%) had private insurance; 18.6% had public, 1.6% had none, and insurance status was unknown for 2.2%. Children with a high-risk condition comprised 1.7% of the study population and 18.9% of otherwise healthy
Discussion
Adherence to national, evidence-based guidance during a vaccine shortage can maximize opportunities for disease prevention. During two PCV7 shortages evidence from review of nearly 3000 medical records showed that physicians adhered to CDC recommendations to defer the fourth PCV7 dose for most healthy children, and that physicians were more likely to withhold doses if the shortage in their practice was severe. Despite severe vaccine shortages experienced in many practices, the proportion of
Acknowledgements
This work was funded by the Centers for Disease Control New Vaccine Surveillance Network project (U38/CCU522352001).
Gerry Fairbrother, PhD has had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
We thank the pediatricians in the Greater Cincinnati area who gave of their time to complete this survey and allow the review of medical records. We also thank Stacey Martin, Fran Walker and the members of the New
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