An influential coronavirus model often cited by the White House coronavirus task force has significantly reduced its U.S. death toll and hospital resource usage projections.
The Institute for Health Metrics and Evaluation at Washington University lowered its death toll projection by nearly 20,000 Wednesday, and now predicts that just over 60,000 Americans will die in the first wave of the COVID-19 pandemic. The IHME model also lowered its predictions for the number of hospital beds and ventilators that will be needed on the country's projected peak usage date by one-third each — now at 94,249 and 16,524, respectively.
The drastic reduction is part of a growing trend among all major models predicting U.S. deaths. Generally speaking, as social distancing methods have been taken into account in later models, death toll predictions in those models have been lowered significantly.
The IHME model, however, has been forecasting with the assumption of "full social distancing through May 2020" for some time now. As far as we know, the latest update was not based on any changes in social distancing measures. Therefore, the implications, at this point, are that the revisions are based on data coming in about the infectious disease itself.
Two weeks ago, the influential epidemiologist behind the "gold standard" Imperial College in London model, Dr. Neil Ferguson, made news when he revised his death toll predictions for the U.K. from 510,000 to 20,000 or fewer. His model also predicted 2.2 million people would die in the U.S. without intervention.
At the time, Ferguson credited the revision in part to the success of social distancing measures, but according to former New York Times reporter Alex Berenson, the U.K.'s lockdown had only begun two days prior, on March 23.
Ferguson had also made his revisions after new data from around Europe suggested the virus' infection rate was higher than initially believed, and as a result, the research team updated the virus' reproduction number. It follows that if more people are infected or have been infected than current data shows, the virus' lethality is diminished.
Similarly, there appears to be some confusion with the White House coronavirus task force model, in regard to how much social distancing efforts are being taken into account in the projections.
On Wednesday, a source close to the task force reportedly told CNN that the eventual death toll could be "way under" the current 100,000 to 240,000 projections. A key factor, the source said, was that the task force assumed only 50% of Americans would observe the government's guidance about social distancing.
Yet, that is not what Dr. Deborah Birx told reporters when unveiling the projections last week.
"If we do things together well, almost perfectly, we could get in the range of 100,000 to 200,000 fatalities," she said adding later that "the best-case scenario would be 100 percent of Americans doing what is required."