(Bloomberg Opinion) -- President Donald Trump isn’t the only one who wants to reopen the country as quickly as possible as it deals with the coronavirus pandemic. Everyone wants that — we want to get businesses and schools up and running again, and we want to get back to our normal lives, which include seeing friends and colleagues in person instead of through Zoom and Skype.

But unlike the president, most people are aware of how dangerous it would be to try to return to normal too soon. In a country of 330 million people, fewer than 1 million will have been tested by the end of this month. (As of Thursday, 519,000 people had been tested, including 122,000 in New York State, according to the Covid-19 Testing Project.) 

We’ve also learned that while older people are especially vulnerable to the virus, the young are hardly immune; letting people return to work now based on their age would be insanely risky. Data compiled by New York City, for instance, shows that 18% of those hospitalized in the city are younger than 44; nationwide, 12% of those admitted to intensive care as of March 16 were between 20 and 44. The truth is, we simply don’t know how widespread the virus is in the population, which means we’re flying blind.

Given the inherent difficulties of the so-called PCR tests (reverse transcription polymerase chain reaction) — which can be done only by health-care workers wearing protective gear, require equipment that is in short supply and can take days to get results — it will be months before scientists are comfortable giving the all-clear sign. The fact that government incompetence delayed significant testing for several months hasn’t helped either. Although the Food and Drug Administration is now allowing people to self-swab, that only reduces the risk for health-care workers; it doesn’t eliminate it.

But there appears to be another way, a side-door approach that might make it possible for some people — maybe even a lot of them — to emerge from self-isolation and get back to their lives. Antibody tests — simple blood tests that can detect whether a person has developed antibodies, and thus immunity, from the coronavirus — could well be the answer. They are easy to administer and easy to scale. They don’t require health-care workers to wear special equipment. Results come back in hours instead of days. And they could be ready for deployment sooner than you might think.

Like anything else, antibody tests have some drawbacks, which we’ll get to shortly. Let’s focus first on their potential benefits. A serology test that can detect antibodies for the coronavirus means it can tell whether someone has developed immunity to the disease. Humans develop antibodies after a virus has made them ill; they are proteins that fight back against a foreign element in the body, eventually repelling it.

Covid-19, as we now know, affects different people differently. Some people don’t survive it, while for many others, it can feel like a bad case of the flu. Scientists also believe that millions of people have most likely contracted the coronavirus without any symptoms at all.

Can you see how useful an antibody test could be? Imagine that health-care workers could test everyone in an entire community. They would immediately learn who had potentially developed immunity and could be freed from self-isolation. The test could also tell whether someone has never been infected by the virus and thus can’t spread it to others. Lower-risk, uninfected people who don’t work in high-contact environments might be able to join the immune population as long as they took proper precautions.

In such a scenario, a potentially large percentage of the population could return to normal life, and only those still at risk would continue to self-quarantine. Crucially, we could identify health-care workers who could treat infected patients without putting themselves at as much risk. Such testing is already available in China, South Korea and Europe, according to David Ho, the well-known scientist at Columbia University. “It is extremely useful for surveying a population,” he told Walter Isaacson last week on the PBS program “Amanpour & Company.”  (He added that the fact we didn’t have tests yet was “inexcusable.”)

Antibody tests can also identify recovered individuals who can donate blood; their plasma can be refined into an experimental Covid-19 treatment for very sick patients. It’s a throwback to a method pioneered over a century ago, but with novel drugs a long way off, it’s what we have.   

Ho said that one problem is that all the manufacturers of antibody tests are abroad, but that’s not quite right. In Hauppauge, Long Island, there is a company called United Biomedical Inc., a 30-year-old, privately held firm with a great deal of experience with viral diseases.  According to Mei Mei Hu, the company’s chief executive officer and co-founder, United Biomedical’s first product was an antibody test for HIV. 

Because much of the company’s capabilities are in Taiwan and China, it was only natural that it got involved in developing both diagnostic tests and a vaccine for Severe Acute Respiratory Syndrome, when that outbreak took place in Asia in the early 2000s. 

“With coronavirus, it made sense for us to jump in,” said Hu, who added that the company’s test is specific enough to distinguish the Covid-19 coronavirus from the many other coronaviruses that cause everything from common colds to debilitating flus.

Earlier this month, the FDA gave the company permission to use its test — even though it has yet to be formally approved — when its validation data showed its tests could detect antibodies 10 days after infection. It set up a subsidiary, Covaxx, for its coronavirus work; one of its investors, as Bloomberg News reported recently, is the foundation of hedge fund billionaire Bill Ackman.

Because Hu and her husband, Lou Reese, who is also a co-founder of United Biomedical, live part of the year in Telluride, Colorado, they approached officials in San Miguel County, where Telluride is situated. With PCR tests in short supply even there, officials decided to test the county’s 8,000 residents.

According to a county press release posted on Tuesday, tests were administered to 645 first responders; they all came back negative, though two had results that could mean “early seroconversion.” Those two people have since self-quarantined, while the others will be tested again in 14 days to make sure there weren’t any early infections that hadn’t been detected. On Thursday, the county issued a testing schedule that will start with seniors and then move on to the general population. If enough people are tested — and the tests are as accurate as United Biomedical’s data suggests — San Miguel County will be the first place in the U.S. to no longer be flying blind.

United Biomedical is hardly the only one working on an antibody test. At the Icahn School of Medicine at Mount Sinai, a group of scientists led by Florian Krammer posted the protocols of an antibody test it has developed with directions on how it can be replicated, according to Science magazine. Others labs are working on antibody tests. Hu says that her company, using its one U.S. facility, could quickly generate 1 million tests a month. It’s easy to see how the test could scale if other companies got involved, which they surely will.

As for the potential drawbacks, there are several. It takes the body some time to develop detectable antibodies — sometimes as much as a week or more after infection — so serology tests are not especially useful as a diagnostic tool. PCR testing will have to continue to catch individuals when they’re at their most infectious so they can be isolated. It’s also critically important that any widely used test doesn’t cross-react with widespread mild coronaviruses, otherwise people may be falsely labeled as immune. 

At this point, no one is sure exactly how long resistance to Covid-19 might last. There’s limited data available from monkeys, but no one should rely on that to make public health decisions. Acquired immunity to viruses can vary from person to person based on the severity of infection and the strength of their immune response. Antibodies to SARS last a long time in infected people, but since that outbreak fizzled out quickly it’s unclear how protective they are. Immunity to mild coronaviruses that cause common colds can last less than a year. Health systems can be fairly confident that someone who tests positive for Covid-19 antibodies will have substantially reduced risk, but scientists will need to keep an eye on them and collect more data over time. 

At a press conference Thursday, White House coronavirus response coordinator Deborah Birx was asked for a status update on the rollout of antibody tests. She noted that tests run through a blood-testing method called ELISA are already available but that the government is looking for a quicker test that can be done at the point of care with just a drop of blood. She did not, however, explain why the absence of an ideal test is preventing widespread use of the ones we have. 

In truth, the antibody tests that are now being conducted, or devised by scientists at places like Mount Sinai, are as good as we can hope for right now. And not a moment too soon.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.

Joe Nocera is a Bloomberg Opinion columnist covering business. He has written business columns for Esquire, GQ and the New York Times, and is the former editorial director of Fortune. His latest project is the Bloomberg-Wondery podcast "The Shrink Next Door."

Max Nisen is a Bloomberg Opinion columnist covering biotech, pharma and health care. He previously wrote about management and corporate strategy for Quartz and Business Insider.

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