Study finds geographical differences in COVID-19 death rates

Aug. 5, 2021

Non-pharmaceutical interventions can be effective at limiting the spread of COVID-19, but individual states need to consider their geographical neighbors for mitigation strategies to be successful, argues a new analysis by researchers at the University of Pittsburgh and Carnegie Mellon University (CMU), according to a news release from UPMC.

The study also found that these interventions need at least three to four weeks to have a measurable effect in dampening COVID-19 spread.

The researchers published their findings in medRxiv, a preprint website, ahead of peer-reviewed publication.

Their analysis revealed that, not surprisingly, stronger statewide interventions — such as universal masking mandates, gathering restrictions and restaurant and bar closures — implemented between March 2020 and March 2021 were associated with fewer COVID-19 deaths.

Of the 23 states that implemented a robust combination of the three measures mentioned above, only about 35% had a mortality rate above the national average. In contrast, of the 28 states with less stringent mitigation strategies, nearly 75% had a mortality rate exceeding the national average.

The scientists also discovered that neighboring states with different intervention strategies and coronavirus restrictions had similar COVID-19 case trajectories, cautioning public health officials to pay attention to states in close proximity.

“We discovered that some groups of states located geographically close to one another — such as in the Midwest — had similar patterns in case counts, despite the fact that their mitigation strategies were different,” said Rebecca Nugent, PhD, Professor and Department Head, Statistics & Data Science at Dietrich College of Humanities and Social Sciences at CMU. “The clustering that we observed may be correlated with environmental conditions, such as temperature and humidity, but we think that it’s most likely a reflection of intermingling due to travel.”

The researchers also found that nearly a month is needed to observe whether the interventions had a desired effect on reduction of COVID-19 cases.

The researchers have created an interactive dashboard,, that reflects the dynamics of implementation of non-pharmaceutical interventions and COVID-19 cases.

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