New COVID-19 Forecasts Show Fragile Balance but Early Promise for Quiet Summer


New four-week COVID-19 projections released today by PolicyLab at Children’s Hospital of Philadelphia (CHOP) show while many U.S. counties are experiencing increased cases of the virus as they reopen, large second waves of widespread community transmission are not currently forecasted in most areas.

The data from the COVID-Lab model add more evidence that increasing temperatures and humidity levels are reducing the risk of the virus spreading over the summer in less-populated counties that remain vigilant with personal protection in crowded indoor locations and maintain limited gathering sizes.

The model, which uses cell phone data to observe travel to non-essential businesses over time, continues to show reductions in social distancing across the country.

Previous projections for some areas that had increased transmission over the last two weeks—represented by counties in AlabamaFlorida and Nevada—stabilized this week.

Given that the model has consistently shown social distancing is the most impactful factor in the spread of COVID-19, the researchers attribute the forecasted ability of these communities to prevent additional community spread to the beneficial effects of weather and suspected personal vigilance in masking and hygiene in many areas.

However, the model continues to underscore the risk in communities that have quickly relaxed social distancing, including HoustonDallas and Phoenix, and some areas in IndianaNorth Carolina and South Carolina.

Furthermore, data show Chicago and Minneapolis are near their peaks in transmission, and the researchers identified new areas of concern in the Pacific Northwest such as the Portland, Ore., metropolitan area and Yakima, Wash.

Finally, a new addition to this week’s analysis includes a map of counties that saw dramatic increases in close proximity encounters over Memorial Day weekend, including vacation destinations like the Atlantic shore, the Poconos, Lake Michigan and southern California.

The researchers will closely watch transmission risk for these communities and their feeder cities over the next two weeks.

David Rubin, MD, MSCE, director of PolicyLab at CHOP

“Overall, despite some persistent and emerging hotspots, there continue to be encouraging signs from our forecasts this week—it appears that weather is continuing to mitigate the risk for widespread community transmission in most areas as they reopen.

However, we are mindful that the stabilization we are observing is quite fragile, as we are just beginning to see the effects of Memorial Day travel in many areas and aren’t yet able to see the impacts of recent crowded protests against racial and social injustices.

It will be critical to monitor the next two weeks of the epidemic to ensure that resurgence risk is really abating in most areas of the country.” said David Rubin, MD, MSCE, director of PolicyLab at CHOP and a professor of Pediatrics at the University of Pennsylvania’s Perelman School of Medicine.

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