Date of Award

2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Pharmaceutical Sciences

Department

Biomedical and Pharmaceutical Sciences

First Advisor

Aisling R. Caffrey

Abstract

One of the ten greatest public health achievements of the 20th century is the control of infectious diseases from vaccination according to the Centers for Disease Control and prevention (CDC). It is recommended by the CDC and the Advisory Committee on Immunization Practices (ACIP) that everyone 6 months and older should receive an annual influenza vaccination. The influenza vaccine is a safe and effective way to prevent the influenza infection and subsequent complications, which is particularly important in children because it has been shown to reduce influenza illness in older adults. Currently, the United States utilizes the National Immunization Survey (NIS-Flu) to provide estimates of annual vaccination rates of children, which are subject to limitations of survey data such as low response and recall bias.

As of 2009, pharmacists were considered approved influenza vaccinators in all states. Pharmacist-administered vaccination improves access to care through increased convenience with proximity, longer hours, and without the need for an appointment. Pharmacists have the authority to vaccinate children against influenza and other vaccine preventable diseases based on different authorization models; protocols, minimum age restrictions, and/or prescription requirements by state. The utilization of pharmacists as pediatric vaccinators, as well as the implications of the restrictions, is not well understood.

Particularly relevant during the current coronavirus disease 2019 (COVID-19) pandemic, pharmacists will have a more substantial role in the vaccination of children. In August 2020, the United States Health and Human Services Department (HHS) granted pharmacists the authority to administer any Food and Drug Administration (FDA) authorized vaccine to children 3 years of age and older under the “Third Amendment to Declaration Under the Public Readiness and Emergency Preparedness Act for Medical Countermeasures Against COVID–19” (PREP Act), which overrides state-level regulatory mandates. Pharmacists are being recognized as well-positioned to expand access to all childhood vaccinations in an effort to combat the alarming decline in all routine pediatric vaccines observed during the onset of the pandemic due to decreased pediatric physician visits and changes in access to healthcare.

This dissertation provides information that can help to understand the trends in utilization of pharmacist-administered pediatric influenza vaccine prior to the PREP Act, as well as determine demographic and clinical characteristics predictive of utilization of a pharmacy setting for receiving influenza immunizations and determine if state-level pediatric vaccination rates by a pharmacist impact state level-influenza diagnoses. For all studies, Optum’s de-identified Clinformatics ® Data Mart Database, a claims data warehouse of commercially insured persons, was used.

In the first manuscript, titled Pharmacist-administered influenza vaccination in children and corresponding regulations, a summary of pharmacist immunization authorization models allowing pharmacist-administered influenza immunization by state from the American Pharmacists Association (APhA) and the National Alliance of State Pharmacy Associations (NASPA) was prepared along with a retrospective descriptive epidemiology study to analyze trends of pediatric influenza vaccination by provider setting using Joinpoint regression. There are three main models under which pharmacists can administer vaccinations: prescription from physician provider, vaccination protocol, or pharmacist independent authority (neither physician prescription nor protocol required). A vaccination protocol specifies which vaccines can be administered under the protocol and vaccine administration procedures, including age limitations, usually agreed upon between state-level pharmacist groups, state-level physician groups, and the state public health department, without the need for a prescription. In an independent authority model, pharmacists have authority to administer vaccines without a prescription or protocol. Regardless of pharmacist authorization models, the minimum age requirements allowing pharmacists to vaccinate against influenza vary by state. There are 14 states with multiple models authorizing pharmacist administration of vaccination to children, which commonly allow children of any age to be immunized by a pharmacist with a prescription, and after a specified age, the protocol/independent authority model becomes effective and a prescription is no longer necessary. In our retrospective cohort, almost 4 million pediatric influenza vaccinations were identified from 2010-2017. The majority took place in a pediatrician’s office, 87.7%; followed by a pharmacy, 3.2; convenience care, 2.3%; emergency care, 0.8%; and other locations, 6.0%. Pharmacist-administered pediatric influenza vaccination was more commonly observed in older children, and less common in the Northeast, where there are more restrictive authorization models. The utilization trend of pharmacist-administered pediatric influenza vaccination was increasing significantly by 19.2% each year over the study period, and the utilization trend of influenza immunization within a pediatrician’s office was slightly decreasing by 0.9% each yeah during the same time.

In the second manuscript, titled Pediatric influenza vaccination rates lower than previous estimates in the United States, the findings Optum’s Clinformatics® Data Mart Database were compared to the findings reported by the NIS-Flu survey estimates from 2010-2017. Recognizing the limitations of survey data, such as use of random-digit-dialed landline and cellular telephone numbers to conduct surveys, response bias from low response rates, recall bias, and known overestimations of vaccination coverage estimates, we sought to describe pediatric influenza vaccination coverage and trends over time using a retrospective cohort study, descriptive statistics, and Joinpoint regression. Current Procedural Terminology, 4th Edition (CPT ®) procedure codes from a commercially insured pediatric population from 2010 to 2017 were captured to build the study population. Over these seven influenza seasons, our study population had an average annual pediatric influenza vaccination coverage of 33.4% compared to NIS-Flu reported vaccination coverage estimates of 56.5% during the same period (p-value <0.0001), resulting in a 51.4% difference between the commercially insured pediatric study population and the NIS-Flu estimate. Vaccination coverage was highest in children 6 months-4-years old at 52.6% (versus 68.8% NIS-Flu, p-value <0.0001), and lowest in children 13-17-years old at 20.1% (versus 42.8% NIS-Flu, p-value <0.0001). Vaccination coverage over time remained stable in the study population (average annual percent change 1.8%, 95% confidence interval [CI] -2.3% to 6.0%, p>0.05) versus significantly increasing by 2.8% in NIS-Flu (95% CI 0.3% to 5.3%, p<0.05). The results from this study validates the need for more accurate vaccination coverage surveillance. In addition, effective interventions are needed to increase pediatric influenza vaccination rates to the Healthy People 2020 target of 70%.

In the third manuscript, titled Demographic and clinical predictors of pharmacist-administered pediatric influenza immunization, multivariate logistic regression was used to determine demographic and clinical characteristics that are predictive to receiving influenza immunization in a pharmacy setting compared with influenza vaccination in pediatricians’ offices using CPT codes in Optum from the 2016-2017 influenza season. Our study found 336,841 children received influenza vaccines by a pharmacist (5.2%) and 94.8% of influenza vaccines administered in pediatricians’ offices (94.8%). The following predictors of pharmacist-administered influenza vaccination were identified: older age of 13-17 years old (odds ratio [OR], 91.51; 95% confidence interval [CI], 73.49-113.94; reference group 6 months to 4 year) and 5-12 years old (OR, 35.41; 95% CI, 28.45-44.07), states with more lenient age restrictions governing pharmacist-administered influenza vaccination of no age restrictions (OR, 26.68; 95% CI, 21.31-33.41; reference group did not allow pharmacist pharmacist-administered pediatric influenza vaccination in children under 18 years old) and minimum age 2-4 years old (OR, 33.76; 95% CI, 26.466-43.07), minimum age 5-12 years old and any age with prescription (OR, 20.93; 95% CI, 16.75-26.16), minimum age 5-12 years old (OR, 15.54; 95% CI, 12.43-19.43), minimum age 13-17 years old and any age with prescription (OR, 13.62; 95% CI, 6.93-11.55), previous year’s influenza vaccination taking place in locations of a pharmacy (OR, 22.18; 95% CI, 21.02-23.41; reference group did not receive influenza vaccine in the year prior), convenience care (OR, 4.15; 95% CI, 3.76-7.58), emergency care (OR, 1.69; 95% CI, 1.33-2.14), and other (OR, 1.13; 95% CI, 1.01-1.25) and in patients living in the South (OR, 2.02; 95% CI, 1.82-2.25; reference Northeast), Midwest (OR, 1.60; 95% CI, 1.45-1.77), and West (OR, 1.38; 95% CI, 1.24-1.55), and routine health examination or follow up appointment in the 6-month baseline period (OR, 1.59; 95% CI, 1.53-1.65). Alternatively, the following were predictive of pediatricians’ office pediatric influenza vaccination: previous diagnosis of acute upper respiratory infection (OR, 0.91; 95% CI, 0.83-0.99); attention-deficit/hyperactivity disorder (ADHD) (OR, 0.90; 95% CI, 0.83-0.98); strep sore throat (OR, 0.87; 95% CI, 0.79-0.96); cough (OR, 0.85; 95% CI, 0.77-0.94); fever (OR, 0.85; 95% CI, 0.76-0.95); obesity (OR, 0.84; 95% CI, 0.73-0.98); otitis media (OR, 0.79; 95% CI, 0.70-0.89); and severe developmental delay (OR, 0.66; 95% CI, 0.53-0.83). The strongest drivers of pharmacist- administered pediatric influenza vaccination were older age, more lenient minimum age restrictions, and previous influenza vaccination in a pharmacy, which is particularly important during the COVID-19 pandemic, where pharmacists are likely to be more involved in vaccinating children, which may result in sustained changes in pediatric vaccination practices.

In the fourth and final manuscript, titled Increased proportions of state-level pediatric pharmacist-administered influenza immunization decrease influenza diagnoses, the proportion of children vaccinated against influenza by pharmacists and the proportion diagnosed with influenza were aggregated at the state-level during the 2016-2017 influenza season, along with potential confounders. The association between state-level pediatric pharmacist-administered influenza vaccination and influenza diagnoses was assessed using backward manual stepwise beta regression. The proportion of children that received an influenza vaccine in a pharmacy varied widely by state. At a state level, we found that influenza diagnoses among children decrease by 6.2% (p=0.0369) per every additional 1% of children vaccinated by a pharmacist, after controlling for potential confounding factors. Fewer influenza diagnoses were observed in states with higher pharmacist-administered pediatric influenza vaccination. Decreasing influenza diagnoses can help decrease the significant burden of influenza in children and throughout communities. Additionally, now that pharmacists have been granted expanded authority to vaccination children due to the COVID-19 pandemic, pharmacists play a key role as vaccine providers and have the ability to reduce rates of all vaccine-preventable diseases among children.

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