Being more densely populated doesn’t boost COVID-19 spread, a University of Utah study finds

(Francisco Kjolseth | Tribune file photo) Aerial view of Salt Lake City. A new study by University of Utah researchers finds that densely populated U.S. city centers are not necessarily more prone to the spread of COVID-19, but that their population size was a factor.

Contrary to popular perception, densely populated U.S. city centers are not more prone to the spread of COVID-19, a newly released study by University of Utah researchers has concluded.

Their review of both infection and death rates across 913 U.S. metropolitan counties through 18 weeks of the pandemic indicates that population size — and not density — more closely corresponds with mortality rates, according to findings published Thursday in the Journal of the American Planning Association.

Urbanized counties with higher densities, in fact, had significantly lower death rates, which researchers said might be explained by better social distancing and access to health care.

The results, said co-author Reid Ewing, professor at the U.‘s Department of City & Metropolitan Planning, “run counter to the recent narrative about escaping compact cities for sprawling suburbs as a way of staying safe from COVID-19.”

“Our main finding is that density isn’t the driving force behind very high infection and death rates. Rather, it’s metropolitan area size,” Ewing said Thursday in an interview.

Recent polls indicate many Americans may pull up stakes and move away from big cities as a result of the virus in what has been dubbed a “Great Exodus,” but it turns out that moving to less populated areas could actually boost their potential vulnerability, he said.

“Compact places seem to promote better adherence to social distancing and provide better acute health care,” Ewing said, “so those contracting the coronavirus are less likely to die.”

The U. professor called the findings “one more reason for urban planners and public officials to favor compact urban development over suburban sprawl.”

A spokesman for regional planning agency Envision Utah said the report “supports the kinds of places Utahns tell us they want for their communities as we grow.”

“We already knew that walkable, vibrant places with destinations close to home improve quality of life, reduce air pollution, and make things more affordable,” said the group’s president and CEO Ari Bruening. “Now we know that they don’t contribute to COVID-19 spread—and could even reduce mortality rates.”

Working with study co-author Shima Hamidi at the Johns Hopkins Bloomberg School of Public Health, Ewing and U. doctoral student Sadegh Sabouri studied data from more urbanized U.S. counties between Jan. 20 and May 25, looking at what experts call “activity density,” which factors in population, jobs and the land area for each county.

Activity density, researchers said, takes into account county residents as well as commuters. The study also considered county education levels, age, race and access to health care, particularly intensive care unit bed capacity.

Metropolitan size proved far more important than density in terms of the virus’ impact, they found.

As an example, New York’s Dutchess County around Poughkeepsie — which is enveloped by the New York City-Newark-New Jersey metro area — has an activity density of 518.1 and has seen a COVID-19 death rate of 4.63 for every 10,000 residents.

Salt Lake County, with one-twentieth the population but, surprisingly, quadruple the activity density — at 2060.2 — has reported a death rate of only 0.61 per 10,000.

Although the analysis did not find a significant link between density and infections rates, Ewing said researchers were surprised at its ties to death rates. In one scenario, after adjusting for other factors, they found that a doubling in county-level activity density was associated with death rates that were nearly 11.3% lower.

But Ewing called the study’s finding “early results” in terms of the anticipated arc of the pandemic. While data since May 25 has so far buttressed the conclusions, he said, researchers intend to continue their work through what could be a second COVID-19 wave that some epidemiologists anticipate in the fall.