More than 85% of Americans are under stay-at-home orders, and at least one-third of the world is under some type of lockdown.

FROM THE BUSINESS INSIDER

The restrictions promote social distancing to “flatten the curve,” or keeping the number of coronavirus infections at a level that won’t overwhelm healthcare systems. But keeping so many people at home is also tanking the global economy and depriving students of education. About 10 million Americans have filed for unemployment insurance in the past two weeks, and the US restaurant industry had hemorrhaged about $25 billion as of March 22. Major universities have switched to remote classes, and public schools are closed indefinitely in states including California, New Jersey, North Carolina, and Pennsylvania.

Plus, of course, staying at home is making many of us lonely and stir-crazy. So the question on many people’s minds is: When will the lockdowns end?

Experts can’t say for sure. The US’s social-distancing guidelines have been extended through at least April 30. According to Davidson Hamer, a professor of global health and medicine at Boston University, some relief could come in mid-May. Epidemiologists at Harvard University think intermittent lockdowns may need to extend into 2022, with social-distancing measures in place 25% to 70% of the time.

Read more: The top scientist at J&J told us how the $350 billion pharma giant will have a coronavirus vaccine ready at ‘warp speed’, then pump out 1 billion doses

However, a new antibody test rolling out in the US within weeks offers a glimmer of hope. These tests will be able to tell whether a person has already had COVID-19, regardless of whether they showed symptoms. A positive result would mean they’re probably immune.

Widespread antibody testing could divide America into two groups: the vulnerable, and the recovered. The latter could slowly go back to work, breathing life into the US economy and helping us get back on track before a vaccine becomes available.

Identifying people who are immune

The coming serological tests use just a few drops of your blood to determine whether you have antibodies for the coronavirus. If so, your body has built up immunity — suggesting that you’ve recovered, even if you never received a positive diagnosis.

Antibody tests differ from the diagnostic tests used to determine whether someone has an active COVID-19 infection. The latter involves taking samples of mucus and saliva and running a test in a lab to see whether those samples contain the coronavirus’ genomic sequence. The results can take one to two days.

A serological test, on the other hand, can tell within minutes whether a person has coronavirus antibodies — similar to the way home pregnancy tests and HIV antibody tests work. A kit includes a needle (to prick your finger), a 3-inch mixing stick, and a test solution.

It’s like dusting for its fingerprints after a crime, rather than catching the virus in the act.

Antibody tests in the works

Henry Schein last week announced the availability of hundreds of thousands of antibody tests in the US that can deliver results within 15 minutes. The company said it expected “significantly increased availability” in April.

In Colorado, United Biomedical is working with one county to test 8,000 residents for coronavirus antibodies.

Other US companies are already selling antibody tests abroad. The California biotech company Biomerica sells coronavirus antibody tests for less than $10 in Europe and the Middle East, while Chembio Diagnostics, a medical-device company based in New York, is sending its antibody tests to Brazil and plans to study them in the US, Reuters reported last week.

The UK government bought 3.5 million at-home antibody tests last week and is looking to distribute them to people who are self-isolating as soon as possible, The Guardian reported. Australia has ordered 1.5 million tests.

Researchers at Germany’s Helmholtz Centre for Infection Research want to send out hundreds of thousands of antibody tests over the coming weeks to residents, Der Spiegel magazine reported Friday. Germany might even issue so-called immunity certificates based on the results.

Gerard Krause, the epidemiologist leading the project, told Der Spiegel that people who are immune “could be given a type of vaccination card that, for example, allows them to be exempted” from restrictions on their movement and travel.

‘The first people to go back to normal life’

As these antibody tests start to be distributed, experts will be able to identify people who have most likely developed some level of immunity to the coronavirus.

In an interview last week, Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said he was confident that recovered coronavirus patients would have immunity, adding that he’d be “willing to bet anything that people who recover are really protected against reinfection.”

That means people who’ve recovered could safely return to work or school.

“Ultimately, this might help us figure out who can get the country back to normal,” Florian Krammer, a professor in vaccinology at Mount Sinai’s Icahn School of Medicine, told Reuters, adding that “people who are immune could be the first people to go back to normal life and start everything up again.”

Krammer and his colleagues gave an overview of their own COVID-19 serological test in a recent study, though it has yet to be peer-reviewed.

Dr. William Schaffner, an infectious-diseases professor at Vanderbilt University, told Reuters that serological tests would be appealing to political and business leaders alike.

“These tests would be very attractive if they’re cost-effective, readily available, and easy to do,” he said.

Antibody tests would also give experts a better sense of how bad the pandemic really is

One of the biggest challenges surrounding the outbreak has been experts’ inability to accurately assess how many people have been infected. That’s imperative because the data informs death rates and tells experts whether we are close to “herd immunity,” the point at which the virus can no longer spread easily because enough people are immune.

“If you could prevent roughly 50% of transmission, you could essentially stop the epidemic,” Stephen Morse, an epidemiologist at Columbia University, told Business Insider.

“The epidemic wouldn’t be able to sustain itself, and the outbreak would fizzle,” Morse added.

The diagnostic tests we have now don’t give experts a clear sense of the true case totals, because many people who likely have COVID-19 aren’t being tested because of limited availability. In New York City, which has about 25% of the US’s coronavirus cases, the Department of Health and Mental Hygiene has told New Yorkers who think they have mild cases to stay home and not seek care (or tests).

“If you think you have COVID-19 and your illness is mild, you do not need to see your health care provider and you will not be tested,” the department’s site said.

What’s more, up to 25% of people infected with the virus show no symptoms at all, Robert Redfield, the director of the Centers for Disease Control and Prevention, said this week. Almost all of those asymptomatic people are not included in official counts either.

The benefits of serological tests cannot be overstated, said George Miller, a professor of pediatrics and epidemiology at the Yale School of Public Health.

“COVID-19 is still spreading rapidly throughout the United States, and antibody tests remain an underappreciated weapon in our fight to stop it,” Miller wrote in an op-ed article in The Washington Post published on Wednesday.

“Armed with such tests, we can provide the public with much more specific information about their own susceptibility, possibly permit immune individuals to return to work, and help people make more informed decisions about when and whether to loosen restrictions on their social activities.”

Morgan McFall-Johnsen and Holly Secon contributed reporting.CORONAVIRUS LIVE UPDATES 17 hours ago