Effectiveness of mobile vaccine clinics on COVID-19 vaccination uptake in the USA: an observational study

Little is known regarding the impact of mobile vaccine clinics (MVCs) on COVID-19 vaccination rates in the USA. This study aimed to evaluate the effectiveness of MVCs in increasing COVID-19 vaccination uptake in the state of Utah.

In this longitudinal observational study, we collected and analysed data on MVCs and COVID-19 vaccinations in Utah from 1 April 2021 to 31 March 2022. The primary exposure was the weekly number of MVC days in host ZIP codes (where MVCs operated). The secondary exposure was the weekly number of MVC days in nearby ZIP codes. The outcome was the weekly first-dose vaccination rate. A mixed-effects zero-inflated beta regression model was used. Confounding variables adjusted in the model included the Health Accessibility Barriers Index, the Resource-Constrained Health System Index, the Social Vulnerability Index (SVI), vaccine hesitancy and prior vaccination rates.

MVCs were deployed for 2760 days (8.5 MVC days per 10 000 residents). MVC density was higher in areas with high proportions of Hispanic populations (11.7 days per 10 000 residents), urban areas (9.0 days per 100 000 residents), and areas with very high SVI (14.9 days per 10 000 residents). Each additional MVC day in a given week reduced the odds of no vaccination in that week by 79.5% (OR=0.205, 95% CI 0.064 to 0.659) in host ZIP codes and by 21.1% (OR=0.789, 95% CI 0.732 to 0.849) in nearby ZIP codes. For ZIP codes with vaccinations, each additional MVC day increased the odds of weekly vaccination rates by 1.6% (OR=1.016, 95% CI 1.001 to 1.032) and by 0.6% (OR=1.006, 95% CI 1.003 to 1.009) in nearby ZIP codes.

MVCs increased COVID-19 vaccination uptake on both host and nearby ZIP codes. Policymakers can leverage these findings to use MVCs as a promising strategy to improve vaccine coverage for future pandemic responses or other vaccination programmes.