A key model that projects coronavirus-related deaths issued a slightly lower projection on Monday despite many Americans resuming normal mobility routines.
The University of Washington’s Institute for Health Metrics and Evaluation adjusted its projection to roughly 143,000, a decrease of 3,000 from last week's projection.
Despite fears that increased mobility would cause a jump in cases, the data so far has not shown a strong correlation between mobility trends and reported cases. IHME Director Chris Murray said on CNN’s “Anderson Cooper 360” on Monday that wearing masks and face coverings is an important factor.
“We were pretty surprised,” Murray said. “We were expecting (the projections) to go up because of a big surge in mobility in the last two or three weeks. But what’s really been fascinating is there has not been a strong correlation between where mobility has gone up and the trend in cases and deaths.”
But what does the data say about mask wearing?
“If you dig deeper and look into the fraction of people in different states who are wearing masks,” Murray said, “we think that is the key difference there, both their behavior and mask wearing. Forty percent of the US wears the mask all the time; about 80 percent wears a mask sometimes. And that is probably helping separate the rise in mobility.”
Until early April, the CDC did not recommend wearing a mask in public space. But as various studies concluded that the virus could be spread asymptotically by simply talking or breathing, the CDC then recommended that Americans wear cloth masks to block potentially infected particles from being spread into the air.
Since the CDC issued its recommendations, a number of major companies have required employees to wear masks during their shifts.
Murray cautioned, however, that the data is incomplete on whether mask wearing is an effective replacement for social distancing.
“That is where we don’t have an exact answer,” Murray said. “We know from the published studies from other viruses, not from COVID, that wearing a mask can reduce the risk of transmission by half.”
Before Monday’s update, the IHME’s model had been trending upward as states began reopening measures, and more Americans were leaving their homes. Last month, the model projected 60,000 US coronavirus-related deaths through August 4.
As of Tuesday, more than 90,000 people had died from the coronavirus since early March, according to Johns Hopkins University data.
Data has shown more Americans leaving their home in recent weeks. In the United States, the IHME uses data from four sources – Google, Facebook, Descartes Labs and SafeGraph – to determine mobility.
The IHME’s model has been one frequently cited by the White House and state-level officials. Beyond death tolls, the models also project hospital bed, ventilator and ICU utilization.
The models show the number of coronavirus deaths in the US slowly declining on a per-day basis through August. Originally, models projected that the per-day death count would see a sharp decline by early May.
To see a state-by-state breakdown of the model, click here.