As New Jerseyans struggle to cope with the sudden demands of social distancing, new data suggests we need to do more — much more — to prevent a worst-case scenario of 1 in 7 residents becoming ill during the coronavirus pandemic.

In fact, without more aggressive efforts to lock down the population with a shelter-in-place order, more than 1.3 million of New Jersey’s nearly 9 million residents could contract and show symptoms of COVID-19, according to an NJ Advance Media analysis based on data from a Rutgers University study.

The analysis paints a bleak picture for New Jersey over the next few months, absent all but the strictest measures of social distancing. Hospitals could become inundated with patients they lack the beds to care for, and state officials would have to scramble for alternative locations to treat the sick. Distancing measures could last for months.

“We don’t know how long it will last, but we should not expect this to be a two-week thing,” said Sarah Allred, an associate professor of psychology at Rutgers-Camden and one of the authors of the study used in this analysis. “We’re talking about an unprecedented strain on our health care system.”

Coronavirus is now in all 50 U.S. states and in more than 100 countries around the world. It has killed more than 10,000 and infected at least 250,000. None of these statistics counts people who haven’t been tested and potentially could infect others, a growing concern among public health officials.

“This is like the silent monster because you don’t have any warning signs” until you’re sick, said Mary Ellen Santucci, a nurse and professor at Rowan University. “I think we’re going to have to be prepared with the Army Corps of Engineers with temporary hospitals. This could go on 12 weeks.”

With the current number of coronavirus cases in New Jersey at 890, it seems hard to imagine a million or more infections. But that’s exactly where New Jersey is headed, according to the Rutgers University-Camden study and the rapid escalation of cases in the past week as more and better testing becomes available.

If that sounds implausible, consider the warning California Gov. Gavin Newsom issued with his shelter-in-place order Thursday night. Newsom predicted 56% of California’s population could contract the virus over the next eight weeks. That would mean more than 25.5 million infections in a worst-case scenario. New York on Friday ordered all nonessential workers to stay home.

Even with a high level of social distancing, the total number of confirmed cases in New Jersey could wind up in the neighborhood of 1.1 million. Only with a very high level — near-total isolation — would the number of cases be held to around 700,000, according to the NJ Advance Media analysis.

With only moderate social distancing efforts, the number swells to 1.3 million, and New Jersey could see more than 250,000 people infected at the same time at the peak of the crisis, which is projected to come in May in that scenario. (The New Jersey projections include only those who show symptoms, not every person carrying the virus.)

Worldwide, most countries are experiencing a death rate between 1% and 3%. As of Friday, 11 of the 890 people known to be infected in New Jersey have died — a death rate of 1.2%. Even at a 1% rate, anywhere from 7,000 to 13,000 New Jerseyans could die from the virus, the data suggests.

This death rate depends on a variety of factors, most importantly the strain on the state’s health care system. The Italian health care system has seen a massive surge in the number of cases, and as a result of inadequate medical resources, the death rate there is now 8%. Keeping that rate down depends on how quickly we can implement effective social distancing and minimize the spike in hospitalizations.

For comparison, 750 New Jerseyans were killed during 9/11, and the state lost about 40 people because of Hurricane Sandy.

The governor’s office did not answer questions about the numbers before publication, but during Gov. Phil Murphy’s Friday news conference, he hinted at more restrictions coming soon.

“We will within the next 24 hours further tighten the screws in terms of the social distancing," Murphy said. "We have no choice.”

The New Jersey infection rates are calculated using a Rutgers model and data on the spread of COVID-19 in Italy. First, the population of New Jersey was split into groups: susceptible, exposed, infected asymptomatic, infected symptomatic, hospitalized and recovered.

By determining how people move from one group to another, their numbers are tracked over time. Only one of these factors — the reproductive rate of the virus — can be controlled by policies such as social distancing. A change in this factor can have a dramatic impact on the spread of coronavirus. Lowering human interaction and stopping the virus’ fast spread is associated with the now-common phrase “flattening the curve.”

With strict isolation, the number of diagnoses would still increase on a daily basis for at least the next five to six months, but it would top out at more than 50,000 active cases on any given day, as opposed to a high end of 160,000 cases on some days under less strict measures.

Stephanie Silvera, an epidemiologist at Montclair State University, realizes the prospect of isolation into the fall is frightening.

“Nobody wants to think about this peaking in October,” Silvera said. “That means some of these measures have to last much longer. It’s been a jarring transition."

The consequences of not doing so could mean inviting the type of grave situation Italy has faced in recent days. This week, Italy’s death toll surpassed China, where the virus is believed to have originated.

“We only have so many hospital beds and so many ventilators,” Silvera said. “If you think of it just from a hospital bed perspective, we’re still going to have people who have heart attacks and strokes and need to be in the hospital and need treatment to survive.”

“You’re talking about making decisions about who’s going to survive and who’s not.”

New Jersey currently has 26,000 licensed hospital beds across the state, according to Kerry McKean Kelly, spokeswoman for the New Jersey Hospital Association, a trade group for hospitals in the state.

She said that hospitals in the state are already starting to roll out their emergency plans, including postponing elective procedures, reopening closed units and exploring alternative treatment sites like medical tents.

“We’re expecting a significant surge,” McKean Kelly said. “It’s such a fluid situation. We continue to do what we do. We find the capacity that exists in the system.

“It might look very different than care in a hospital bed that you might see on a regular day.”

Allred, the Rutgers-Camden professor and author of the study, said the projections were based on existing epidemiological models of the coronavirus using recent data from the virus’s spread in Europe. Her group looked at how many are likely to get infected and wind up hospitalized. She added that these epidemiological models have been trusted since the 1950s.

The danger of the virus is for the 15% to 20% who do wind up showing symptoms, the large number of them — between 40% and 55% — will need to be hospitalized, the study found.

“No individual should panic because every individual is at a low risk of getting sick,” Allred said, adding that despite large projected infection rates and possible hospital bed shortfalls, “we can decrease that need by enacting strong social distancing measures.”

The study, she said, does rely on a couple of educated guesses, such as those around the number of people presently infected, which is difficult to know without widespread testing and makes a big difference in how quickly the peak hospital bed shortfall is reached.

The numbers indicated, depending on the speed of the spread, that at the peak of the shortfall, there will be between 4.5 and 13 New Jerseyans who need a hospital bed for every 1 that is available.

“If people can stay six feet apart from each other, we’re not going to need as many beds at one time,” Allred said, adding that officials already need to be thinking about more than just hospitals to care for patients.

“We have to start thinking about what high school auditoriums we’re going to use.”

About this data

The model used for creating these predictions is an extension of the traditional SEIR model of disease spread. The primary modification is including two infected classes: symptomatic and asymptomatic. The range of effective reproductive rates used in the figure is 1.4-3.8. The latent period is 5 days, infectious period is 4 days, hospitalization period is 10 days, asymptomatic infection proportion is 0.81 and hospitalization rate is 0.35 of those that are symptomatic.

The graphic uses a forward Euler solver with a time step of 0.1 days to create the solution from the model. The initial conditions used are 20 exposed individuals, 10 asymptomatic and infected individuals, 2 symptomatic and infected individuals, 0 hospitalized and 0 recovered individuals. Then, assuming a low degree of social distancing, the model is run forward till the total number of infected and symptomatic individuals reaches the case numbers recorded till date. The end values for each group of individuals are then used as initial conditions for another solution assuming the degree of social distancing set by the user. This way the setting of the reproductive rate starting today is decoupled from the reproductive rate from the beginning of the infection till date.

For additional questions on details of the modeling, reach NJ Advance Media developer Arjun Kakkar at akakkar@njadvancemedia.com.

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Payton Guion may be reached at PGuion@njadvancemedia.com. Follow him on Twitter @PaytonGuion.

Nick Devlin may be reached at ndevlin@njadvancemedia.com. Follow him on Twitter at @nickdevlin.