How much longer will we be inside — and then what happens?

How long will Illinoisans be staying inside because of the coronavirus? Right now, bank on mid-April — at the earliest.

Gov. J.B. Pritzker’s stay-at-home order, which took effect on Saturday, March 21, is set to expire on Tuesday, April 7.

Expect the governor to extend that. Mayor Lori Lightfoot predicted Friday Pritzker would push the order “deep into April,” though Pritzker afterward was non-committal.

Three Chicago medical experts who have been monitoring the situation agree that state public health officials need a minimum of four weeks to make sure that all existing cases of COVID-19 infection in Illinois have been identified and isolated.

Based on the start of Pritzker’s order, that would take the date to Saturday, April 18. Even then, a host of factors could push things back, including the degree to which people can be tested and how full hospitals get.

The experts with whom I spoke are Dr. Bala Hota, an epidemiologist who is vice president and chief analytics officer at Rush University Medical Center; Dr. Elaine Morrato, founding dean of the Parkinson School of Health Sciences and Public Health at Loyola University Chicago, and Dr. Robert Murphy, director of the Institute for Global Health and Center for Global Communicable Diseases at Northwestern Medicine.

While they can’t predict for certain when the outbreak will be under control in Illinois, they do agree on this: Lifting the stay-at-home order should not happen on an arbitrary date such as Easter (April 12), as President Donald Trump has suggested.

COVID-19 symptoms typically do not become apparent until 5 to 7 days after exposure, Hota said. Severe cases on average require hospitalization after an additional 5 to 7 days. Seriously ill patients may remain contagious for longer still.

Criteria for Pritzker lifting the order should include statewide availability of on-demand COVID-19 testing, the experts agreed. There should also be — at minimum — a decline in the rate of increase in daily new cases. Murphy said the number of daily new cases should show a steady downward trend before stay-at-home restrictions are eased.

Another important consideration is how close hospitals are to capacity, Hota said. If the health care system becomes so overloaded that patients do not receive adequate care, more deaths will result from all causes, not just COVID-19.

On-demand COVID-19 testing would require the ability to test at least 4,000 people per day statewide, Murphy said. That’s comparable to the number of tests given per capita in South Korea during the peak of its successful effort to tame the outbreak. The South Korean approach is considered the gold standard for COVID-19 control.

The other experts agreed 4,000 tests per day was a reasonable target.

Pritzker said that, as of March 24, Illinois had the ability to test 2,000 people per day, but expected to be able to test 4,300 per day within two weeks.

As of Saturday evening, Illinois had recorded 3,491 COVID-19 cases, the eighth highest total for any state, including 465 new cases. On average, the number of daily new cases is doubling every three days, Illinois Department of Public Health figures indicate. New cases have been rising sharply since March 9.

In South Korea, new cases rose sharply starting on Feb. 19 and began declining on March 8 — 19 days later, according to data from Worldometer, an international statistics website.

South Korea was able to control the COVID-19 outbreak in a relatively short time because it had ample infrastructure in place due to experience with mini-epidemics such as the 2003 SARS outbreak, Murphy said. South Korea tested up to 20,000 people per day at the height of the coronavirus crisis there.

It also instituted rigorous “contact tracing,” identifying and testing everyone whom infected people had come in contact with through a combination of detective work and technology.

Some public health experts and technologists in the U.S. and other countries advocate the use of smartphone applications and other advanced tools to aid in contact tracing.

South Korea uses a special text messaging service that must be installed on all smartphones sold in that country. If someone tests positive for COVID-19, their path through the community is traced based on information provided by the patient plus credit card transaction location data and security camera video obtained with the patient’s permission.

South Korean authorities have the authority to obtain a patient’s smartphone location data but don’t invoke this unless the patient refuses to cooperate, Ryan Shin, a South Korean who lives and works in Seoul, said in an email. Shin, who graduated from the University of Illinois at Urbana-Champaign with an engineering degree in 2012, is CEO of a Korean tech startup.

Screenshot provided by Ryan Shin

The service then broadcasts a “safety guidance message” to the phones of all who live in the patient’s neighborhood. The alert overrides other activity on the phone and displays the message accompanied by an audible alarm.

Recipients click on a link to access a page listing the patient’s activities. Shin provided a typical page, shown in the accompanying illustration.

“It says on March 21 she landed at Incheon Airport at 4:30 p.m., took a bus, and rode the elevator in a certain building with a mask on,” Shin said. “On March 22 she went to the hospital for a virus test and then went to the supermarket.”

South Koreans who become ill can use a different smartphone app or visit a website to report their symptoms to a central office, Shin said. The senders receive instructions based on the severity of their symptoms.

Smartphone apps have been developed in other countries to perform similar functions. For example, an app introduced in Singapore uses Bluetooth technology to detect other people’s phones nearby. If a phone owner tests positive for COVID-19, authorities can use the data recorded on the phone to contact others with whom the patient has crossed paths.

The Chicago experts had varying opinions about whether such technology would gain acceptance in this country.

“I never heard of anybody doing it in the U.S.,” Murphy said. “There are a lot of privacy issues. I can’t imagine it happening here.”

“It’s worth exploring,” Morrato said. “It seems like a natural extension of things going on in the private sector that could be redeployed for surveillance. But we need evidence it will make a difference in saving lives as we consider the ethical implications.”

What should happen after the Illinois stay-at-home order is lifted is a matter of debate.

Once COVID-19 is under control in Illinois, it likely will still be raging elsewhere and could easily be reintroduced by visitors. This has occurred in some Asian countries that relaxed restrictions, the experts noted.

Regardless, the U.S. needs to rethink how it deals with pandemics. COVID-19 won’t be the last, the experts agreed.

“It’s not a question of if but when,” Morrato said.