Completion of multiple-dose travel vaccine series and the availability of pharmacist immunizers: A retrospective analysis of administrative data in Alberta, Canada

Pharmacists in a number of countries are being trained in the administration of injections with the aim of improving access and adherence to vaccinations. However, little is known about population-level adherence to multiple-dose travel vaccines, and whether the availability of pharmacist immunizers is associated with adherence. Health administrative data from Alberta, Canada, from April 2008 to May 2017 identified adults dispensed at least one vaccine for hepatitis A, hepatitis B, Japanese encephalitis, or rabies. Individuals were coded as completers or non-completers of the vaccine series based on the number of doses dispensed over a time period comprising the duration of the standard series plus 6 months to account for late doses. The association between the proportion of Alberta pharmacists with injection authorization (according to pharmacist registration data) and completion of vaccine series was assessed using linear regression. Over the study period, 24,164 patients initiated a vaccine series for hepatitis A monovalent, 195,480 for hepatitis B monovalent, 169,802 for combined hepatitis A&B, 1,726 for Japanese encephalitis, and 1,908 for rabies. There were fewer than 5 individuals receiving Japanese encephalitis vaccine per year from 2008–2010 or rabies vaccine from 2008–2009. While statistically significant positive associations were seen across all vaccines except for Japanese encephalitis, the magnitude of these associations was small. Each 1% increase in the proportion of injections-authorized pharmacists saw a corresponding increase in the proportion of individuals with completed vaccine series by 0.31% for hepatitis A monovalent, 0.19% for hepatitis B monovalent, 0.22% for combined hepatitis A&B, and 0.21% for rabies. This may suggest that challenges remain with implementing reminder systems to ensure adherence among travellers. Strategies to develop or improve patient and clinician reminder systems in pharmacies for travel vaccines should therefore be explored.