How many people in Pa. will be infected with the coronavirus? Scientific modeling is trying to find the answer.

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HARRISBURG — With the rate of new coronavirus cases rapidly increasing in Pennsylvania and across the United States, some of the country’s top scientists are racing to understand how bad the outbreak is going to get and what measures can be taken to save as many lives as possible.

State Health Secretary Rachel Levine said her department was working with universities to answer those questions. But as of Friday, the state’s modeling was not finished, and though officials have promised to share “projections” publicly, there’s no time frame on when that might happen.

That stands in contrast to officials in other states. The Oregon Health Authority, for example, has released modeling that shows how many infections could occur under different scenarios. The state, with a population of 4.2 million, had 319 confirmed cases as of Friday, while Pennsylvania’s cases have topped 2,000.

In other states, like California and New York, top officials have said publicly how many additional beds and ventilators will be needed to handle the crisis. This week, Gov. Andrew Cuomo predicted New York’s cases will peak in about 21 days, while New Jersey’s state health commissioner has also provided an estimate.

It has been more than 20 days since Pennsylvania reported its first coronavirus cases, and state officials have released no such data or modeling. The number of new cases continues to grow exponentially, and deaths from the disease have begun to accelerate, from two to 22 in less than a week.

While state officials have consistently said the situation will deteriorate, they’ve been unable to say just how bad the outbreak might become. Instead, they’ve emphasized Gov. Tom Wolf’s efforts to slow the spread and prevent sick patients from overwhelming hospitals.

“We don’t know when the surge is going to be. We’re tracking that. We have different modeling,” Levine said Friday. “To be honest with you, I would go with what Dr. [Anthony] Fauci said, which is: The virus determines the timetable. We don’t determine the timetable,” referring to the director of the National Institute of Allergy and Infectious Diseases.

In the absence of state projections, hospitals and members of the public are turning to other models to understand where Pennsylvania is headed.

Levine pointed to one from the University of Pittsburgh. There, a computer platform called FRED projects that patient hospitalizations will peak at 100,000 in the state, according to a report Friday by the Pittsburgh Post-Gazette.

“These are very scary numbers, and one thing I hope to impress upon people is that this is serious,” Mark Roberts, director of the Public Health Dynamics Lab at Pitt’s Graduate School of Public Health, told the newspaper. “Social distancing is seriously important not only for yourself but the rest of the community. That’s the only thing you can do.”

In Philadelphia, the University of Pennsylvania has created a model that allows hospitals to use locally available data to anticipate how many COVID-19 patients will need treatment. Health systems can use projections from the model, called CHIME, to plan their responses to an expected surge in demand for intensive care beds, said co-creator Mike Draugelis, chief data scientist at Penn Medicine.

It also helps health systems around the country weigh the risks and benefits of continuing elective surgeries and other procedures, Draugelis said.

“I think we're arming them with information that previously wasn't really available at a local level,” he said.

One of the most elusive statistics is just how many people overall are infected because of the lack of mass testing and because some people with the virus don’t show symptoms. Penn is testing people hospitalized in the Philadelphia area and feeding those results into CHIME, Draugelis said.

The big variable is how many people are carrying the virus without showing symptoms, Draugelis said. Testing a random sample of people would help to get at that number.

Draugelis said knowing the rate of “asymptomatic carriers” is essential to understanding how many people overall are infected with the virus. It’s also important for projecting how many more people are going to get sick.

On the national level, a team of data scientists has created a model called COVID Act Now, which urges politicians and officials to adopt aggressive social distancing policies.

Founder Max Henderson said his team used data from other countries — along with what’s available in the U.S., such as deaths from COVID-19 and the number of available hospital beds — to gauge how many people are likely to be hospitalized and how long hospitals could support that need. The site notes, “This model is intended to help make fast decisions, not predict the future.”

In Pennsylvania, the model gives a grim forecast of what sick people and health-care workers could face in the coming weeks. If no actions to restrict movement or encourage social distancing were put into place, upward of 255,000 people in the state could die. But that’s an unlikely scenario.

Actions taken by Wolf over the last two weeks, including shutting down thousands of businesses and issuing a “stay-at-home” order for 19 counties, are essential to thwarting worst-case scenarios and reducing future deaths, Henderson said.

If the order was extended to the entire state and effectively enforced, the model projects that hospitals would not be overwhelmed, fewer than 3% of the population would be infected, and about 4,000 people in Pennsylvania would die from the illness.

“That comes from changes in trends we’ve seen in other places like California and Washington,” Henderson said. “We know it works.”

Asked Thursday if social distancing was working in Pennsylvania, Levine, the health secretary, said there’s “lag time” between implementing the measures and seeing the impact. Wolf has thus far declined to extend the stay-at-home order statewide, saying he wants to take a “measured” approach.

Henderson noted COVID Act Now has limitations. It estimates how easily the virus spreads, and doesn’t adjust for things like population density or weather. It also doesn’t factor in if a hospital bed has intensive care services, such as a ventilator, though that’s an additional data point researchers are working to add soon.

As a result of those limitations, COVID Act Now has been criticized by some conservative news outlets, which claim it’s causing elected leaders to panic and close down businesses despite early data from some states showing it may have overestimated hospitalizations.

No projection is perfect, but the model is serving an important function in a situation where every day counts, said Leo Nissola, a San Francisco-based physician and scientist at the Parker Institute for Cancer Immunotherapy.

Nissola, who is not part of the project but has endorsed it, noted that stopping the virus is vitally important for many of his patients, who will probably have more serious symptoms if they get sick. At the same time, his patients also are likely to be affected by long-term disruptions to other medical procedures.

To him, health-care companies face the difficult task of throwing significant resources at treating people sick with the coronavirus while also continuing to treat people with other illnesses. But the role the public plays in determining what happens in the weeks ahead is paramount.

“This COVID-19 crisis is unlike anything we’ve seen, and it does require new, bold, and aggressive policy solutions,” Nissola said.

Sarah Anne Hughes of Spotlight PA contributed to this article.

Correction: This story has been updated to reflect how Penn is testing to feed its model.

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