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COVID-19 vaccines reduce the risk of infection, severe disease, long COVID, and death.^1-5 Given the effectiveness of these tools, the reasonable next question is how to maximize their use to protect the greatest number of people from harm, especially those at greater risk for infection and disease progression. Although COVID-19 vaccines were free and obtainable in 2021 and as early as December 2020 for some health care workers (HCWs), a considerable proportion of people in the US chose not to get vaccinated.^6-8 This fact was of increasing concern as novel variants began to appear in the first half of 2021—first Alpha and Gamma followed by the Delta wave during the summer and fall of 2021. The Delta wave was associated with a dramatic increase in infection and hospitalization rates, disproportionally affecting unvaccinated individuals^9,10 and peaking nationally in September 2021.¹¹ As a result, policymakers at the federal, state, and local levels began to develop interventions, including vaccine mandates, for various sectors, including state workers, police officers, firefighters, and HCWs. Importantly, while the science supporting vaccines at the individual level at the time was robust, the impact of policy tools like vaccine mandates was not well understood despite the widespread use of similar vaccine requirements for other infectious diseases. Wang and colleagues¹² investigated this challenging and critically important question: do public policies that required health care workers to get vaccinated increase vaccine uptake?

To address this question, Wang et al¹² evaluated 16 states with vaccine mandates in 2021 that required HCWs to be vaccinated against COVID-19 compared with 29 states that did not require vaccination. The vaccination status of 31 142 HCWs aged 25 to 64 years was obtained from the Household Pulse Survey¹³ between May and October 2021. The study period included the 2 months prior to the first state mandate through October 11, 2021. The end of the study period was chosen to prevent potential attribution of vaccination decisions to the HCW vaccine mandate that was implemented by the Centers for Medicare & Medicaid Services (CMS) in early November 2021. For the analysis, Wang et al¹² used a standard staggered difference-in-differences event study model to capture the outcomes of the separate times of mandate implementation and differences in vaccine uptake among state HCW populations.

Using 2-week survey blocks for data collection and analysis, by the second week after a mandate was implemented, Wang et al¹² found an increase in the proportion of HCWs ever vaccinated or who had completed or intended to complete the primary vaccination series. This represented a nearly 4% increase in vaccination rates in mandate states compared with nonmandate states. The proportions returned to baseline by the following 2-week block and remained close to baseline through the rest of the study period. In states with a test-out option, there was no detectable increase in vaccination rates even in the early period (2 weeks after mandate implementation). When analyses were stratified by states with no test-out option, statistically significant increases in HCW vaccination were seen in the first and second 2-week blocks. Interestingly, HCWs aged 25 to 49 years had the largest increases in vaccination after mandate implementation, ranging from an almost 6% increase in the first 2 weeks to just over 7% in weeks 3 and 4.

These results join those of other studies that found an association between vaccine mandates and increased vaccinations in specific populations.^14-17 Although HCWs in the study by Wang et al¹² had high rates of vaccination initially, mandates were associated with increases in baseline proportions ranging from 84% to 88%, usually within the first 4 weeks after the mandate. The rate of increase was likely affected by the planned implementation of the CMS mandate as well as local mandates from hospitals and health care systems, including in nonmandate states, both of which may have diluted the measured effect estimates for the state mandates. Importantly, researchers are gaining more information on the specific tools that can be used for employer vaccine mandate policies, including not having a test-out option.

Assuming that other studies will continue to replicate these findings, other questions about mandates remain unanswered. Vaccination mandates are sociopolitical decisions meant to increase the safety of the population, but how much of an increase in vaccination uptake is needed to warrant them? How is that increase measured, especially when faced with a novel pathogen like SARS-CoV-2? What is the ethical framework for developing a mandate? In the face of a novel pandemic, mandates may generate controversy even among the vaccinated population and are complicated by a significant volume of misinformation and disinformation.^18,19 Studies like that by Wang et al¹² provide more information that could be used to design mandates and communicate the impact of future mandates, providing much needed and better measures of the perceived tradeoffs of governmental action in preparation for the next pandemic and in the prevention of nonpandemic infectious diseases.

Published: August 14, 2024. doi:10.1001/jamanetworkopen.2024.26820

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2024 Lynch JB. ÌÇÐÄvlog Open.

Corresponding Author: John B. Lynch, MD, MPH, Division of Allergy & Infectious Diseases, Department of Medicine, University of Washington, Harborview Medical Center, 325 9th Avenue, Box 359778, Seattle, WA 98104 (jblynch@uw.edu).

Conflict of Interest Disclosures: None reported.