During the COVID-19 pandemic, pharmacists took a leading role and spearheaded national vaccination efforts. Depending on the state, pharmacists have had immunizer status for years; however, data are limited on the impact of pharmacist involvement on immunization uptake and outcomes.

Researchers conducted an updated systematic review and meta-analysis to explore the impact of pharmacist involvement as immunizers, advocates, or both on immunization rates and other outcomes indirectly related to vaccine uptake.

A systematic search was conducted of MEDLINE, Embase, and Cochrane Central Register of Controlled Trials from inception to February 28, 2022 to identify randomized, controlled trials (RCTs), cluster RCTs, or observational studies with a comparison group that measured immunization rates and related outcomes, such as improvement in vaccine hesitancy and vaccine resistance, vaccine appropriateness, vaccine compliance, patient awareness, attitude towards vaccination, and satisfaction with vaccination. Observational studies included non-RCTs, controlled before and after studies, retrospective cohorts, and cross-sectional surveys. The pharmacists’ interventions were either as facilitators, advocates, immunizers, or advocates/immunizers. The pharmacists’ interventions were compared with usual care (i.e., routine or the standard of care received by patients) or to interventions without pharmacist involvement.

A total of 14 RCTs and 79 observational studies were included in the analyses. Of the RCTs, 11 assessed the impact of pharmacist involvement on immunization uptake (e.g., change in pharmacists’ confidence in vaccine administration following training, impact of electronic messaging on vaccine advocacy, or Facebook sessions to address COVID-19 vaccine hesitancy). Among the studies examining the pharmacist’s role, two studies involved pharmacists as immunizers, 11 as advocates, and one as both an immunizer and advocate; no studies involved pharmacists as facilitators. Most RCTs studies were conducted in the United States or in other high-income countries (10 out of 11) with only one study conducted in an upper-middle income country (i.e., Jordan). Pharmacists were involved in 17 identified comparator interventions, which included, for example, reviewing medication and vaccine histories and providing patient education.

Pooled analyses of two RCTs of pharmacists as immunizers demonstrated a statistically significant increase in immunization rates (risk ratio [RR] 1.14; 95% CI, 1.12-1.15). Similarly, pooled analyses of 10 RCTs of pharmacists as advocates were also associated with a statistically significant increase in immunization rates (RR 1.31; 95% CI, 1.17-1.48). However, heterogeneity was high among this latter group.

The strongest evidence existed for pharmacists as immunizers (RR 1.14; 95% CI, 1.11-1.17) or advocates (RR 1.19; 95% CI, 1.07-1.32) for the influenza vaccination. The pharmacists’ involvement in the community setting (six RCTs; RR 1.17; 95% CI, 1.06-1.28) and in the hospital setting (four RCTs; RR 2.82; 95% CI, 1.13-7.03) were both associated with a significant increase in influenza vaccination rates. In this latter setting, there as a high risk of bias in one study. Removal of that study still demonstrated a significant impact of pharmacists’ involvement in the institutional setting (RR 3.74; 95% CI, 2.67-5.22). Other positive effects of pharmacists’ actions observed in the RCTs were reductions in vaccine hesitancy and resistance and an increase in intent of patients to vaccinate.

Most of the observational studies were also conducted in high-income countries, with 81% being performed in the U.S. The pharmacist’s role involved immunizer in 19.0%, advocate in 44.3%, and facilitator in 2.5% of the studies. A similar trend was seen in the observational studies with pooled analyses of nine studies of pharmacists as immunizers (RR 2.17; 95% CI, 1.71-2.75) and 17 studies of pharmacists as advocates (RR 2.01; 95% CI, 1.66-2.44) demonstrating statistically significant increases in immunization rates. Pharmacist involvement in any practice setting significantly increased the immunization rate of all types of immunizations. Other positive impacts of pharmacists’ interventions included improving vaccine compliance, appropriateness, and patients’ attitudes towards vaccinations.

The limitations of this study included that the overall quality of evidence from the RCTs was low to moderate (moderate for pharmacist in general as immunizers and as advocates for influenza vaccination in the community). The quality of evidence from observational studies ranged from low to very low.

Despite these shortcomings, this study demonstrated the important role that pharmacists play in public health by positively affecting immunization rates.

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