As the number of cases of COVID-19 continues to accelerate, researchers and epidemiologists at the Maine Center for Disease Control are using several scientific models to prepare for an outbreak that could kill between 100 and 1,000 residents.The wide variance in the fatality forecast, as well as the potential overwhelming of the state’s health care system, reflects the imprecision of epidemiological modeling. Included in those forecasts are scientists’ evolving understanding of the novel coronavirus that is now hitting its peak in certain parts of the U.S.
[What Mainers Need To Know About The Coronavirus]
Also underpinning the forecasts is Mainers’ adherence to social distancing restrictions implemented by Gov. Janet Mills - something that’s difficult to track or quantify, but central to Maine’s fight against an outbreak that’s already killed 10 residents as of Monday, while hospitalizing nearly 100 others.
“In the absence of a vaccine, the human distancing restrictions are all we’ve got against COVID-19,” said Dr. Nirav Shah, director of the Maine CDC.
Shah revealed the CDC modeling with three reporters at the Maine Emergency Management Agency offices in Augusta. He emphasized repeatedly that the models were “for planning, not predictions,” adding that the forecasts were designed to produce a range of scenarios so that state public health officials can prepare for a medical surge that could overwhelm Maine’s critical care beds or require more people to operate ventilators than are currently in the workforce.
While Shah said he believed the chances of a worst-case scenario seemed small, he also said it’s important to understand how devastating COVID-19 could be in a state with the oldest median age in the country.
“This is a really serious disease. The fatality rate is not anything to trifle with. It spreads a lot more easily than the flu,” he said.
The forecasts center on a range of assumptions that include what’s known as the basic reproduction number, or how many people can be infected by coming into contact with just one person. Shah says that number is determined by how infectious the disease is, but also how society and people respond to it by limiting human interactions, travel or frequent handwashing.
“When we talk about flattening the curve, this is precisely what we’re talking about,” he said.
For example, one person with the flu can transmit the virus to between one and two people. Early research shows that one person with COVID-19 can spread the virus to nearly four people, a single digit increase over the flu that can have far more devastating consequences.
Likewise, reducing the COVID-19 reproduction number even by a small percentage can produce widely different results.
Shah showed models forecasting the effects of a 60- and 70-percent decrease in reproduction on the availability of critical care beds in Maine hospitals. A 70 percent decrease showed that Maine’s inventory of critical care beds could be sufficient. A 60 percent decrease showed a significant shortfall.
The same scenario applied to COVID-19 case numbers. A 70 percent decrease in the reproduction rate showed case counts slowly accumulating over the next few months before leveling off. A 60 percent decrease showed cases skyrocketing to cases in the thousands each day.
In nearly all of the modeling scenarios, Maine could see the peak of the outbreak in the next couple of weeks.
Shah said the duration will depend on whether Mainers continue to follow social distancing rules. He acknowledged that measuring adherence to social distancing is also tricky. But he said state officials are tracking it through traffic and cellphone data. He said the state is using publicly available cell phone data supplied by carrier companies, not accessing it on its own.
Shah says Maine CDC is also using county-level traffic data gathered by the Maine Department of Transportation.
Early traffic data show a 50 percent drop in travel. In Cumberland County, Shah said there was an additional 17 percent reduction. Not reflected in those findings is the impact of Gov. Mills’ stay at home order issued last week. Shah said that it can take two to three weeks to measure the impact of any kind of restriction, whether it’s on gatherings of people or on travel.
He said aggressive actions and adherence to them are Maine’s best chance against COVID-19.
Many of the governor’s mandates began as recommendations. Given that changes in Mainers’ behavior can play a significant role in reducing the reproduction rate of COVID-19 cases, Shah was asked if the governor’s restrictions were aggressive and timely enough.
“Yeah, I think so,” he said. “I think the order and the timing in which we took the steps was when they needed to be.”
He said social distancing remains the core strategy, but the aggressiveness of that strategy - such as enforcement measures - could change if it looks like Maine’s reproduction rate of COVID-19 is tracking with a worst-case scenario.
Shah said he debated whether to show reporters the fatality forecasts knowing that they could be wrong.
“I want to be straight because I know that’s a question that’s on everyone’s mind,” he said. “And ... this is serious stuff.”
Shah also said that the epidemiological models are not glimpses at the future, but instead a range of possibilities - possibilities that are highly sensitive to people taking the potential outcomes seriously.
Originally posted 10:00 a.m. April 7, 2020
