How many will die of COVID-19 in North Carolina? Predicting the toll isn't easy

2020-03-30 | The News and Observer

March 30-- Mar. 30--RALEIGH -- On Sunday, researchers at the University of Washington were predicting that 2,411 people would die of COVID-19 in North Carolina before the outbreak subsides, and that the need for hospital beds statewide would exceed supply in the coming weeks.

On Monday, they updated their forecast, reducing the potential death toll in the state to 1,721. They also now think the state has enough hospital beds to meet expected demand, though they still think the state will be short 278 intensive care unit beds.

What changed? The earlier prediction did not take into account Gov. Roy Cooper's statewide stay-at-home order, scheduled to go into effect at 5 p.m. Monday. The order, in effect until April 29, bans gatherings of more than 10 and directs people to stay at home except to visit essential businesses, to exercise outdoors or to help a family member.

Those additional steps to enforce social distancing will reduce the spread of the coronavirus that causes COVID-19, said Dr. Ali Mokdad, a professor at Washington's Institute for Health Metrics and Evaluation.

"If people adhere to them, there will be less demand on our medical resources," Mokdad said in an interview. "This is a great example that if you implement social distancing you will see the impact of that."

The change in the Washington forecasts also shows the difficulty in predicting the effects of coronavirus and the health care system's ability to handle it. Scientists are still learning about the virus' behavior.

But hospitals and government health officials need to make forecasts to try to ensure they can handle the surge in COVID-19 patients when it comes. Dr. Mandy Cohen, Secretary of the Department of Health and Human Services, said Monday that the state doesn't know when the outbreak will peak in North Carolina but that it is working with data scientists at Duke University, UNC Chapel Hill and Research Triangle Institute to try to figure it out.

"We're going to learn more in the coming days and weeks to try to give us as much certainty as we can to understand this," Cohen said during a press conference. "These are all predictions, and this virus is something we are all learning about."

Dr. Joseph Rogers, chief medical officer for the Duke University Health System, says Duke is watching all sorts of models about how many patients will need to be hospitalized and has a handful of teams working internally on their own predictions.

What the models say about demand on hospitals is "concerning," Rogers said, but there are still a lot of caveats and uncertainty in the predictions. It's early yet, he said, with only about 1,300 confirmed cases of COVID-19 in a state of 10.5 million residents.

"As we get farther along into this disease in North Carolina, I think we're going to find the models get much better at predicting what's going to happen," he said.

The UNC Health system is also consulting a series of COVID-19 models, at least one of which shows demand for hospital beds exceeding the current available supply. UNC is preparing for that worst-case scenario, said Christian Lawson, director of emergency services, in part by buying more hospital beds and planning for places to put them.

"If we don't need them great," Lawson says, "but if we do we want to have them on site."

Ask Lawson about the most likely scenario and he says that changes day to day. A big factor, he says, is how much the public responds to pleas to avoid social contact.

"What we've seen, in talking to our fellow medical colleagues across the country, is that models were showing one thing, but then social distancing and stay-at-home orders were issued and it drastically shifted the model," he said.

Public officials from President Trump on down have argued that reducing the pace of coronavirus spread -- flattening the curve -- can greatly reduce the potential strain on hospitals and the health care system. Last week, Wake County published a set of predictions that illustrate that.

Wake determined that if the number of coronavirus cases doubles every four days before April 15, the county would have more than 2,000 cases, with 307 requiring hospitalization and 92 needing an intensive care unit, well within the capacity of local hospitals.

But if the number of cases doubles every three days, the county could see as many as 33,000 cases, with nearly 5,000 requiring hospitalization and 1,485 needing an ICU. That would overwhelm hospitals in the county, which together currently have 1,767 hospital beds and just 152 in an ICU.

Hospitals work to prevent bed shortage

Whether the Triangle and North Carolina has a shortage of hospital beds during the coronavirus outbreak will depend not only on demand but also on supply.

For weeks now, hospitals have been postponing non-urgent surgeries and procedures to free up existing beds, and that is paying off. UNC Medical Center in Chapel Hill is at about 70% capacity, Lawson said, down from a normal occupancy rate of about 95%.

Duke Health's three hospitals in Durham and Raleigh are all below 70% occupied, with more than half of beds at Duke Raleigh now available, Rogers said.

Hospitals are also looking to increase the number of beds by re-purposing space already within their walls. Both UNC and Duke are drawing up plans to convert operating rooms into ICUs and to house less critical coronavirus patients in rooms where patients normally wait before and after surgery.

"All hospitals have spaces like that that we use in different ways today," said Rogers, who added that Duke estimates it can increase its bed capacity by 25% to 30% if it needs to.

"We don't have a lot of time to plan, but we do have some time," he said. "There's a lot of work that's being done across the system and across the Triangle to make sure we have the resources we'll need to take care of patients."

Mokdad, at the University of Washington, said researchers there will update their predictions daily, as new information comes in. If hospitals succeed in creating new ICU beds, for example, the predicted shortage in North Carolina will decrease.

But he said the biggest single factor the researchers have found so far in reducing the impact of coronavirus on the health care system is social distancing.

"These measures do work," he said. "We've seen it first hand."