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State COVID-19 vaccine mandates in 2021 were linked to increased vaccine uptake among healthcare workers in states with no test-out options and among workers younger than 50 years of age, according to a cross-sectional study.

In states with vaccine mandates for healthcare workers, the proportion of healthcare workers ever vaccinated against COVID-19 increased by 3.46 percentage points (95% CI 0.29-6.63, P=0.03) in the 2 weeks after announcement of the mandate, when compared with non-mandate states, reported Charles Stoecker, PhD, of Tulane University School of Public Health and Tropical Medicine in New Orleans, and colleagues.

That result represented a 3.93% increase in the already high percentage of about 88% of healthcare workers previously vaccinated in mandate states, the study authors wrote in .

Also, the proportion of healthcare workers in mandate states that completed or intended to complete the primary vaccination series increased by 3.64 percentage points (95% CI 0.72-6.57, P=0.02) when compared with non-mandate states, representing a 4.23% increase from a baseline proportion of about 86% of vaccinated workers.

Of note, the differences in vaccine uptake between mandated and non-mandated states in this primary outcome of the study were likely "mainly driven by vaccination uptake increases in states with no test-out options and among younger hospital workers," commented study co-author Yin Wang, MA, also of Tulane University, in .

The test-out option allowed healthcare workers in mandate states to forego vaccination and receive regular COVID-19 testing as an alternative. In states with no test-out option, there was a 2.9 percentage point (P=0.03) increase in healthcare workers ever vaccinated at weeks 0 and 1 after mandate announcement, which increased to 3.77 percentage points (P=0.01) at weeks 2 and 3. These results represented increases of 3.32% to 4.31%, relative to a baseline vaccination rate of 87.35%.

In light of these findings, "a level of stringency may be necessary to ensure effectiveness of mandates," the authors suggested.

Researchers also found that the proportion of vaccinated younger healthcare workers -- ages 20 to 49 -- working in mandate states increased by about 6 percentage points (95% CI 2.37-9.57, P=0.002) by 2 to 3 weeks after announcement of the mandates, compared with healthcare workers in states without mandates.

Vaccine mandates were first introduced in 17 states beginning in June 2021 as a response to rising cases of the SARS-CoV-2 Delta variant. Then in November of that year, the Centers for Medicare & Medicaid Services (CMS) instituted a federal mandate requiring all staff in federally funded nursing homes and healthcare facilities to receive COVID-19 vaccinations.

Intense debate about the mandates quickly followed. "Divergent attitudes were also found among healthcare workers, with acceptance rates for vaccine mandates varying from 35% to 92% depending on different sampled cohorts," Stoecker and colleagues wrote. Although the mandates have since been lifted, "they serve as valuable examples of the potential effectiveness of immunization efforts for future pandemics."

"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?" asked John Lynch, MD, MPH, of the University of Washington in Seattle, in an . "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," he added.

Since the in May 2023, "each state now has to consider on their own recognizance whether it's important for them to have a mandate," Stoecker noted in the podcast. "Health organizations themselves need to decide -- if their states aren't going to mandate it -- if they want to mandate it themselves. But now this evidence is out there and it says what kind of effects you can achieve, even when your workforce is already relatively highly vaxxed."

Researchers looked at 16 states with vaccine mandates in 2021 that required healthcare workers to be vaccinated against COVID-19 and compared them with 29 states that did not require vaccination. They obtained vaccination status of 31,142 healthcare workers ages 25 to 64 years from the U.S. Census Bureau's Household Pulse Survey conducted biweekly between May and October 2021. About 43% were from mandate states. The survey included two questions about receipt of the COVID-19 vaccines and completion of the vaccine series, as well as demographic information.

Compared with healthcare workers in non-mandate states, workers in mandate states were more likely to be Hispanic, college graduates, and to have annual household incomes of $100,000 or more. They were less likely to be Black or white. About 84% of healthcare workers had already been vaccinated in the pre-mandate period, but the proportion was higher (88%) in mandate states than non-mandate states (82%).

The study period included the 2 months before the first state mandate through October 2021, and collected and analyzed data in 2-week survey blocks after mandate implementation. The end of the study period was chosen to prevent potential attribution of vaccination decisions to the CMS vaccine mandate that was implemented in early November 2021.

Limitations to the study included that healthcare workers in control states may have had employer vaccine mandates or other mandates, so results may be conservative regarding the link between state COVID-19 vaccine mandates and vaccine uptake. In addition, the terminology for specific healthcare facilities was not the same across official documents, so the scope of vaccine mandates may have varied by state. Also, vaccine uptake measures were based on self-reported vaccination status.

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