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Infectious-Disease Experts Think Washington State’s Slow Reopening Will Mean Fewer Cases

On Wednesday, the total number of COVID-19 cases stood at 1,382,304, with deaths at 78,343. The U.S. is continuing its phased reopening, but states are rolling back restrictions at different rates — and their residents are out and about to widely varying degrees.

To investigate the consequences of different approaches, we return to a survey of infectious disease experts organized by Thomas McAndrew and Nicholas Reich, both biostatisticians from the University of Massachusetts Amherst. For many questions, respondents are asked to provide their best estimate, as well as a best-case and worst-case possibility. Structuring the survey in this way lets the organizers generate probabilistic consensus forecasts, a tool that can answer questions about how likely various scenarios are.

In this week’s survey, conducted May 11 and 12, most experts predicted that the total number of positive cases in the U.S. would be more than 1.45 million on May 17. The experts also estimated some measures of the disease in Pennsylvania and Washington, two states with different reopening plans.

How many confirmed cases will be reported on May 17?

In recent weeks, the researchers have been given distinct ranges of total confirmed COVID-19 cases and asked to assign a probability to each bin. Last week, the experts nailed their forecast: The expert consensus was that on May 10 there would be between 1.3 million and 1.45 million confirmed positive cases reported by The COVID Tracking Project. The actual number reported on May 10 was 1,322,807.

This week’s expert consensus puts the most probable range at somewhere between 1.45 and 1.55 million total confirmed cases on May 17. But the expert consensus also assigned a 10 percent probability to a more pessimistic scenario — one in which there are more than 1.6 million cases.

How many deaths in Pennsylvania on June 13?

With the president attempting to pressure Pennsylvania Gov. Tom Wolf into reopening his state more quickly, there is increasing tension between the governor’s three-phase plan and some counties’ desires to open up faster. There have been 58,698 total cases of COVID-191 in Pennsylvania, and the current death toll stands at 3,943. The experts were asked to forecast the total number of deaths in the state on June 13. The consensus projection was 7,239 dead, with an 80 percent chance that the actual number will fall between 5,249 and 10,472.

One expert even believes that the death count could plausibly reach 30,000 in the Keystone State, though that view is not shared by the rest of the panel.

How many new daily cases in Washington?

Even as it extended its stay-at-home orders through the end of the month, Washington state has begun a four-phase reopening plan that Gov. Jay Inslee’s administration is calling “Safe Start.” The state plans to remain in each phase for a minimum of three weeks. The first phase of Safe Start allows for some recreation and construction activity, along with auto sales and commercial pet walking. At the time of the survey, five counties with fewer than 75,000 residents and no new reported cases in the past three weeks were allowed to begin Phase 2, which allows the resumption of activity in restaurants, house cleaning services and hair and nail salons, among other businesses.

The experts were asked to forecast the average new cases per day in Washington for the first week of June. Their consensus estimate of 332 is in line with case counts near the peak of the outbreak in late March and early April, with an 80 percent chance that the actual daily average will fall between 158 and 644 cases.

Experts were also asked to estimate the average daily case count in the first week of June if all Washington counties were allowed to enter Phase 2 on May 16.2 They forecast an average of 554 new daily cases under such a plan — an increase of 67 percent over their estimate of cases under the current plan.

What’s interesting about this prediction is that 554 average new daily cases is more than the 441 new cases on March 23, which is thus far the highest number of new cases reported in a single day. Since the experts were asked to predict the average number of new daily cases over the course of a week, they appear quite pessimistic about the effects of an early rollout of Washington’s Phase 2 plan.


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Footnotes

  1. Including confirmed and probable cases as of Wednesday afternoon.

  2. And the order was not rescinded before June 1, 2020.

Josh Hermsmeyer is a football writer and analyst.

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