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Homeless and incarcerated people had significantly lower Covid vaccination rates than others in Minnesota, according to a new study. Its authors say the findings highlight lingering inequities, even in a state that has prioritized vaccinating socially vulnerable groups.

The study, published Monday in Health Affairs, is the first to analyze such a wide swath of people — its data set compared about 90% of Minnesota residents. It found just one third of people in jail and less than 30% of homeless people had been fully vaccinated by the end of 2021; less than 10% of people in these groups had received boosters. About 70% of the state’s residents overall had been vaccinated.


This kind of analysis could show which public health programs are working well and which are falling short of their stated goals, the researchers say — though they stopped short of making specific policy recommendations.

“There’s a lot of different health outcomes — Covid-19 vaccination being near the top of our attention these days — where there’s room for improvement,” said Katherine Diaz Vickery, a family care doctor with the Health, Homelessness, and Criminal Justice Lab at the Hennepin Healthcare Research Institute and one of the study’s lead authors.

“Rather than just pointing to the programs we’re starting or the dollars we’re investing, it’s important that we really hold ourselves accountable to what the data show us about the effectiveness of these programs,” she added.


Minnesota’s efforts to encourage Covid-19 vaccine uptake included offering incentives and hosting vaccine drives specifically designed to reach underserved populations, among other things. Minnesota’s health department even has a vaccine equity team, which tracks vaccination rates based on zip codes; each zip code is classified in one of four groups based on the CDC’s Social Vulnerability Index.

But the results from Monday’s paper shows that the state’s programs haven’t fully addressed some lingering inequities.

In addition to lower vaccination rates among homeless people and people in jails, Vickery and her colleagues also found inequalities in the vaccination rates of different racial groups. In every setting, Black and Hispanic Minnesotans had lower vaccination rates than their white peers; in some cases, the gaps were as large as 12 percentage points.

“One of the biggest surprises is just the persistent nature of the disparities as we went across groups,” said Riley Shearer, an M.D./Ph.D. student at the University of Minnesota who was also a lead author of the paper.

“And then, as we observed with boosters at the end of 2021, those disparities became even more severe.”

Anecdotally, researchers have known about the challenges of getting people in jails vaccinated. This paper adds evidence to support those anecdotes, said Lauren Brinkley-Rubinstein, a researcher at the University of North Carolina’s school of medicine whose work has focused on the health of incarcerated people.

But there is reason to suspect that more could be done, particularly when it comes to certain incarcerated populations. A greater proportion of people in Minnesota’s state prisons were fully vaccinated by the end of 2021 compared to Minnesota’s general population. “Prisons tend to have more stable populations, that is: they are there for longer than jails,” noted Brinkley-Rubinstein. “This allows for more opportunities to vaccinate people, especially with a two dose regimen.”

The analysis required combining data from four different sources — an electronic health records consortium that covers several large hospital systems and private clinics, the state’s centralized immunization database, a database used by more than 200 organizations that work with homeless people, and the state department of corrections.

“Even getting one of these datasets can be difficult for someone who’s not sitting in that agency. And certainly connecting them across agencies is a significant undertaking,” said Julie L. Swann, a researcher at North Carolina State University who studies health care systems, who added that the analysis should nevertheless be possible for other states, too.

The data set analyzed in Monday’s paper is extensive, but it doesn’t cover every single person — and some of the people not included in the dataset may be particularly vulnerable to Covid-19 or other health issues.

People who were homeless and didn’t receive support from the participating organizations, for example, couldn’t be included in the data. “I know from the clinical work I do that there is a large and growing segment of the homeless population which does not feel supported and dignified […] by existing homeless services,” said Vickery. “Those people are not present in this data.”

Minnesota’s statistics also reflect only Minnesota’s policy choices — which means states that took different approaches might have significantly different trends.

Shearer also noted that this study was only intended to show the results of Minnesota’s vaccination efforts, not tease out which policies might be causing the trends they observed. “We don’t try and claim one policy is better than another in this study,” he said.

For example, several jurisdictions chose to make J&J’s vaccine a centerpiece of efforts to get vaccines to homeless people — in part because it only required one shot. And during an April 2021 webinar, experts from the Minnesota Department of Health and Hennepin County — including one of the authors of Monday’s paper — attributed the relatively low rates of vaccination among people experiencing homelessness to “challenges completing vaccine series.” The vast majority of people who had been vaccinated at that point received the Moderna vaccine.

However, Monday’s paper did not analyze data on which vaccine brand people had received.

“We don’t necessarily think that is the place to focus on,” Vickery said.

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