Date Published: February 14, 2018
Publisher: Public Library of Science
Author(s): Sarah E. Wilson, Hannah Chung, Kevin L. Schwartz, Astrid Guttmann, Shelley L. Deeks, Jeffrey C. Kwong, Natasha S. Crowcroft, Laura Wing, Karen Tu, Mohammad Ali.
In August 2011, Ontario, Canada introduced a rotavirus immunization program using Rotarix™ vaccine. No assessments of rotavirus vaccine coverage have been previously conducted in Ontario.
We assessed vaccine coverage (series initiation and completion) and factors associated with uptake using the Electronic Medical Record Administrative data Linked Database (EMRALD), a collection of family physician electronic medical records (EMR) linked to health administrative data. Series initiation (1 dose) and series completion (2 doses) before and after the program’s introduction were calculated. To identify factors associated with series initiation and completion, adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) were calculated using logistic regression.
A total of 12,525 children were included. Series completion increased each year of the program (73%, 79% and 84%, respectively). Factors associated with series initiation included high continuity of care (aOR = 2.15; 95%CI, 1.61–2.87), maternal influenza vaccination (aOR = 1.55; 95%CI,1.24–1.93), maternal immmigration to Canada in the last five years (aOR = 1.47; 95% CI, 1.05–2.04), and having no siblings (aOR = 1.62; 95%CI,1.30–2.03). Relative to the first program year, infants were more likely to initiate the series in the second year (aOR = 1.71; 95% CI 1.39–2.10) and third year (aOR = 2.02; 95% CI 1.56–2.61) of the program. Infants receiving care from physicians with large practices were less likely to initiate the series (aOR 0.91; 95%CI, 0.88–0.94, per 100 patients rostered) and less likely to complete the series (aOR 0.94; 95%CI, 0.91–0.97, per 100 patients rostered). Additional associations were identified for series completion.
Family physician delivery achieved moderately high coverage in the program’s first three years. This assessment demonstrates the usefulness of EMR data for evaluating vaccine coverage. Important insights into factors associated with initiation or completion (i.e. high continuity of care, smaller roster sizes, rural practice location) suggest areas for research and potential program supports.
Prior to the implementation of vaccination programs, rotavirus was a common cause of childhood gastroenteritis, responsible for up to 40% of acute gastroenteritis presentations (depending on season) and a cause of substantial healthcare utilization [1,2]. In the pre-vaccine era in Canada, one-third of children with rotavirus gastroenteritis sought care in an outpatient setting, 15% used emergency department services and 7% required hospitalization . Two live attenuated oral rotavirus vaccines are authorized for use in Canada: RotaTeq® (RV5, Merck Canada Inc.) since 2006  and Rotarix™ (RV1, GlaxoSmithKline Inc.) as of 2007. Canada’s National Advisory Committee on Immunization (NACI) issued recommendations for the use of rotavirus vaccines in 2008 and 2010[5,6]. In August 2011, Ontario implemented a universal publicly-funded rotavirus immunization program with RV1 vaccine at 2 and 4 months of age. Prior to the program, parents could purchase the vaccine with a physician prescription. The publicly-funded program has been associated with a 71% reduction in hospitalizations due to rotavirus infection . However, a formal coverage evaluation has been challenged by two issues. First, the routine processes for coverage monitoring in Ontario delay assessment until the time of school entry. Second, physicians are not remunerated for the delivery of this oral vaccine (in contrast to parenteral vaccines); consequently there is no immunization delivery billing code available in health administrative data. The use of electronic medical records (EMRs) may help fill this information gap.
We identified 13,534 children who were born between January 1, 2008 to December 31, 2010, and August 1, 2011 to July 31, 2014 in EMRALD, of which 99% were successfully linked to administrative databases. After study exclusions, there were 12,525 children included in our coverage assessment: 5,039 born during the period of private vaccine eligibility and 7,486 eligible for publicly-funded vaccine (Fig 1). Characteristics of the study children and their mothers were compared to the 2013 Ontario birth cohort (Table 1). The two groups were similar across most characteristics with very few exceptions, as assessed by standardized differences. A greater proportion of study children lived in rural areas and had lower continuity of care. The 335 unique EMRALD family physicians providing care to study children were more likely to be women, less likely to be foreign-trained, with smaller roster sizes and with fewer years in practice compared to the usual primary care providers (family physicians and pediatricians) seen by the 2013 Ontario birth cohort (Table 2), as assessed using standardized differences.
Despite the absence of a physician billing code specific to rotavirus vaccine and the challenges of timely assessment of infant vaccine programs using school-based coverage methods, we were able to conduct a detailed coverage assessment in Ontario by using family physician EMRs. Rotavirus vaccine uptake (series completion) increased each year of the first three years of the program from 73% to 84%, with excellent compliance with age-based dosing guidelines. Linkage to health administrative datasets allowed for factors associated with series initiation and completion to be identified.
Rotavirus vaccine uptake increased in the three years following the program’s launch in Ontario. Several maternal/family and physician characteristics were associated with series initiation and completion. This assessment demonstrates the usefulness of EMR data for evaluating vaccine coverage prior to school-entry in Ontario. Our ability to link EMR data to health administrative datasets generated important insights into factors associated with initiation or completion (i.e. continuity of care, roster size, practice location) which should be explored in future research and considered within potential program supports.