Politics aside, did indoor vaccine mandates work?

Those who fail to learn from history, Winston Churchill warned in the aftermath of World War II, are doomed to repeat it. As the pandemic recedes and a sense of normalcy returns to our lives, those words are as relevant as ever. We are all eager to put three years of isolation, loss and hardship behind us. But unless we draw thoughtful lessons from our pandemic response, we leave ourselves just as vulnerable to the next crisis.

Governments at all levels took extraordinary steps to mitigate COVID-19’s impact. Among the most restrictive were rules requiring proof of vaccination to enter indoor venues like restaurants, gyms and event centers. From the summer of 2021 to the spring of 2022, nine major U.S. cities (New York, Philadelphia, Los Angeles, Chicago, Seattle, Boston, New Orleans, San Francisco and Washington, D.C.) adopted these mandates, affecting tens of millions of Americans. Vaccines work, but after thorough research, we see no evidence that city mandates did.

The goals of indoor vaccine mandates were simple: to encourage vaccination and curb the spread of COVID-19. In September 2021, officials in King County, Wash., predicted “that the vaccine verification policy at restaurants, bars, and gyms/fitness centers alone could have a significant positive impact, preventing between 17,900 and 75,900 infections, 421 and 1,760 hospitalizations, and 63 and 257 deaths locally over six months with the order in place.” Todd Unger, an executive at the American Medical Association, claimed, “Vaccine mandates increasingly appear to be one of the most effective ways to increase our vaccination rates and make sure that more people are protected. The science is clear…”

In this case, the science wasn’t so clear. To be sure, reams of data showed that COVID vaccines were safe and effective. But the effect of indoor vaccine mandates was uncertain. At the time, there was some evidence that similar rules in Canadian provinces and European countries had boosted vaccination rates, but there was little indication they would be effective in the context of a U.S. city. And no one had examined their effects on COVID-19 morbidity and mortality.

Now, a rigorous analysis of these policies has failed to detect any positive impact.

A new study just released by one of the authors of this op-ed offers the first empirical analysis of the effects of indoor vaccine mandates in the United States, using advanced statistical techniques to analyze health data from hundreds of cities spanning December 2020 to April 2022. Cities that never adopted a vaccine mandate served as a comparison group, helping to determine what would have happened in “treated” cities had they not implemented such a policy.

Across all nine major cities, indoor vaccine mandates had an insignificant effect on COVID-19 cases and COVID-19 deaths. Moreover, the effect of the mandates on vaccination rates was also statistically negligible. In short, these policies did little, if anything, to blunt the pandemic.

It’s less clear why this is the case. Perhaps city-level mandates have an inherent flaw: Residents can avoid the restrictions simply by traveling outside the city limits. When mandates are imposed by a state, province or even an entire country, they’re harder to avoid. An unvaccinated person in France would have had to travel to another country to legally eat at an indoor restaurant, whereas the same unvaccinated person in New York City could simply have traveled to New Jersey.

Another factor behind the results may be that vaccine mandates made people feel protected from infections, leading them to make more frequent visits to crowded venues, or to be less diligent in following social distancing and masking guidelines. This complacency may have offset some (or all) of the benefits of vaccination.

Amid the pandemic, government officials had no choice but to make decisions with incomplete information. But too many cities were willing to impose vaccine restrictions based on speculative evidence and questionable reasoning. The need to do something to control the pandemic may have blinded well-meaning policymakers to the costs of the policy (including further stoking divisions among Americans and threatening the viability of businesses that were forced to turn away non-compliant customers and employees) while failing to keep people safe.

We now know that instituting indoor vaccine mandates was almost certainly counterproductive. May that lesson not be soon forgotten.

Vitor Melo is a postdoctoral fellow with the Open Health Project at the Mercatus Center at George Mason University, a fellow with the Initiative on Enabling Choice and Competition in Healthcare at the University of Chicago and author of a new Mercatus Center study on indoor vaccine mandates. Liam Sigaud, a research assistant with the Mercatus Open Health Project, contributed to this commentary.