Model: Mask wearing could cut U.S. daily deaths by two-thirds

JACKSON — A new model says if universal mask wearing went into effect today, the daily COVID-19 deaths in the United States could be cut by two-thirds by Nov. 1.

The Institute for Health Metrics and Evaluation at the University of Washington has been one of the most prominent sources of coronavirus modeling and projections since the pandemic began. It has added a new layer to its models in recent weeks: mask wearing.

Given current conditions, the model says, COVID-19 deaths in the U.S. will reach 628 per day by Nov. 1. 

If nationwide universal mask wearing were instated, that number falls to 205 per day, a 67% decrease.

The model shows that if mask wearing started right away, a decrease in cases and deaths would start about two weeks from now. That’s because the virus has an up to 14-day incubation period. A dramatic decrease in daily deaths follows almost immediately, with a roughly 50% drop by the end of August.

For Wyoming, the data is a bit behind the times. 

The model says the state’s path is basically set and that requiring masks to be worn on a statewide level won’t change much in terms of the number of deaths or expected cases.

However, the last time the model updated its Wyoming data was July 11, and the state has seen hundreds of new cases since then and four deaths. Every time the model updates its data, the projections change, so the infusion of the past 10 days’ worth of information could make a difference.

In response to a request for comment regarding the Wyoming data, the Institute for Health Metrics and Evaluation said it would “look into” the matter.

Another explanation is that Wyoming has relatively few coronavirus-related restrictions in place. The model takes into account restrictions and the pace at which they are easing, but that doesn’t apply to Wyoming because other than group-size restrictions and some social distancing, the statewide orders pretty much allow business as usual.

For Teton County, the model doesn’t mean much of anything. The most granular data the institute uses is at the state level, according to its website, so it can’t predict whether the recently passed mask order will have a local impact.

Even though the institute’s models are generally well-regarded by public health officials, it is just one model. And no matter how good the model, it must make some guesses that might not match reality.

“Each makes a set of different simple-minded assumptions,” Stanford University epidemiologist Mark Cullen told the Jackson Hole Daily.

For the mask projections, the institute assumes that mask wearing will begin within 7 days and that the current easing of restrictions will continue. It also assumes that limits on the movement of people will go back into place if local daily deaths reach eight per 1 million people.

For Wyoming, the model assumes that the state will never reach such a rate, with deaths plateauing around now. At the end of the day, the model is just one piece of information.

“There are many different models, but there are many things we don’t know,” Cullen said. “I try not to be obsessed with one model over the other.”