The impact of pharmacist involvement on immunization uptake and other outcomes: An updated systematic review and meta-analysis

Abstract

Background: The underutilization of immunization services remains a big public health concern. Pharmacists can address this concern by playing an active role in immunization administration.

Objective: We performed a systematic review and meta-analysis to assess the impact of pharmacist-involved interventions on immunization rates and other outcomes indirectly related to vaccine uptake.

Methods: A systematic literature search was conducted using MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases from inception to February 2022 to identify randomized controlled trials (RCTs) and observational studies in which pharmacists were involved in the immunization process. Studies were excluded if no comparator was reported. Two reviewers independently completed data extraction and bias assessments using standardized forms. Meta-analyses were performed using a random-effects model.

Results: A total of 14 RCTs and 79 observational studies were included. Several types of immunizations were provided, including influenza, pneumococcal, herpes zoster, Tdap, and others in a variety of settings (community pharmacy, hospital, clinic, others). Pooled analyses from RCTs indicated that a pharmacist as immunizer (risk ratio 1.14 [95% CI 1.12-1.15]), advocator (1.31 [1.17-1.48]), or both (1.14 [1.12-1.15]) significantly increased immunization rates compared with usual care or non-pharmacist-involved interventions. The quality of evidence was assessed as moderate or low for those meta-analyses. Evidence from observational studies was consistent with the results found in the analysis of the RCTs.

Conclusion: Pharmacist involvement as immunizer, advocator, or both roles has favorable effects on immunization uptake, especially with influenza vaccines in the United States and some high-income countries. As the practice of pharmacists in immunization has been expanded globally, further research on investigating the impact of pharmacist involvement in immunization in other countries, especially developing ones, is warranted.

Figure 1

Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart. Abbreviations used: CENTRAL, Cochrane Central Register of Controlled Trials; RCT, randomized controlled trial.

Figure 2

Impact of pharmacist involvement in immunization rate of all types of vaccine by role. Abbreviation used: DL, DerSimonian and Laird method.

Figure 3

Impact of pharmacist involvement in immunization rate of all types of vaccine by study setting. Abbreviation used: DL, DerSimonian and Laird method.

Supplement III

Risk of bias assessment for observational studies according to intention-to-treat analysis.

Supplement IV

Summary plot of risk of bias assessment for observational studies according to intention-to-treat analysis.

Supplement V

Forest plot of Impact of Pharmacist involvement on Immunization rate of influenza vaccine by pharmacist role.

Supplement VI

Forest plot of Impact of Pharmacist involvement on Immunization rate of influenza vaccine by study setting.