Mobile Vaccination Units Substantially Increase COVID-19 Vaccinations : Evidence From a Randomized Controlled Trial

Background: Governments around the world use mobile vaccination units (MVUs) to increase COVID-19 vaccine uptake, but the causal effect of MVUs has not yet been evaluated.Methods: In a randomized controlled trial (RCT) with 20 Swiss communities (10 treatment and 10 control) in August 2021, we sent MVUs to treatment communities for four hours on a single day. The experimental sample comprises 20,414 adults who were unvaccinated against COVID-19 at this point. The research team designed the RCT and the government was responsible for administering the vaccines.Results: The vaccination rate in the sample of the treatment group surpassed the rate in the control group by a factor of 3.4 (plus 9.0 percentage points) over a three-week period. The increase was present and highly statistically significant for women, men, and for all age groups. We found no evidence of cannibalization of vaccinations at other service locations.Conclusion: The offer of MVUs is highly effective in raising vaccination rates, even at a later point in the vaccination campaign, when people had ample time to contemplate their vaccination decision. Our findings suggest that MVUs did not just serve as a tool to reach people faster, but rather to vaccinate more people overall