The US now has more covid-19 tests than it knows what to do with

We have the greatest testing program anywhere in the world," US President Donald Trump told reporters on June 23. We test better than anybody in the world. Our tests are the best in the world, and we have the most of them. By having more tests, we find more cases." Trump went on to say the US had done 25 million tests-far more than the couple of million that even large countries" had done elswehere.

Let's start with what he got right: as of June 23 the US had successfully run 27,553,581 covid-19 tests (meaning tests that look for the presence of the virus, to determine whether someone is currently infected or not). So he's more or less in the ballpark there. And current sources suggest that, yes, the US has carried out more tests than any other country.

But the US testing program can't be considered best in the world." The US has run 83.24 tests per thousand individuals, according to numbers from Our World in Data. By comparison, Russia, which is also being hit hard by the virus, has run 120.07 tests per thousand people.

And the US is currently testing about 500,000 people per day, far behind the 5-million-a-day mark that Trump said the country was closing in on in late April. That is not necessarily because it can't test more people: the country's testing capacity has significantly improved since the pandemic began. Still, a Washington Post survey of about 20 states last month found the country was running at least 235,000 fewer tests a day than it could have run. While places with spikes in infections-like Arizona-are facing shortages, large swaths of the country are actually reporting underutilized availability.

On the one hand, this could mean we can immediately test more people-we just have to get the word out. But on the other hand, that greater capacity also presents an opportunity to rethink the role of testing during a pandemic as we seek to reopen the economy. Finding new infections is not the only way to use this untapped reservoir.

How bad is the situation?

Most health experts will tell you that testing is vital in controlling the pandemic. On a personal level, testing can tell you whether you're infected, regardless of whether you're showing symptoms. If you test positive, you can isolate yourself to protect others, and contact tracers can try to find people you may have exposed, to isolate them as well. Testing can also tell us where new infections are popping up, so authorities can limit the scope of the outbreak and warn neighboring communities that might be hit next. If we don't have enough testing, we can't do any of these things well, and that lets the virus spread faster.

Another issue: the jury is still out on exactly how much asymptomatic cases contribute to transmission of covid-19. But if it turns out asymptomatic transmission is a major problem, we're only going to get ahead of this if we're able to identify people who don't know they're infected," says Ann Kiessling, the director of the Bedford Research Foundation, a lab in Massachusetts. They're the ones who are going to infect you tomorrow."

So how much testing should the US really be doing? American public health experts have never agreed. The economist Paul Romer has said we need to be doing 30 million tests a day. A model developed by the Safra Center at Harvard called for 10 million tests a day.

Ashish Jha, the director of Harvard's Global Health Institute, and his colleagues came up with a much more modest number for what's acceptable: 900,000 a day. Their model begins with the idea that everyone with even mild symptoms of influenza-like illness should be tested. Jha's best guess at the moment is that there are probably about 100,000 new cases of covid-19 throughout the country every day. He and his team developed their model on the assumption that 20% of those people won't show symptoms, which would mean there are 80,000 new symptomatic infections every day that can be tested. (The true rate of asymptomatic infections is under debate.) Plus, each positive case is estimated to have about 10 contacts who ought to be identified and tested. Plug in a host of other variables (like the rate of new infections and the impact of reopenings), and you get a minimum of 900,000 tests a day.

I would take 30 million tests if we had it," says Jha. I think 3 to 5 million would be great-I think that's an ideal range. But 900,000, we think, is a minimum we need to aim for."

So why isn't the US isn't reaching this number? In the early stages of the pandemic, the system simply couldn't meet the demand. People who did not have clear symptoms of a moderate or severe infection were often turned away from testing. By the end of April, the country was still running under 300,000 tests a day, according to the Covid Tracking Project.

Nowadays larger labs around the country have acquired more equipment and resources necessary to run many more covid diagnostic tests, and many smaller labs have pivoted to focus entirely on covid testing. And yet, as the Washington Post found, a state like Utah is running only a third of the 9,000 tests it could run every day. In California, Governor Gavin Newsom has admitted that the state could test 100,000 people a day but is using only 40% of that capacity. The Boston Globe reported a few weeks ago that Massachusetts had the potential to process 30,000 tests a day but was averaging less than one-third of that. Thousands of tests in Oregon, Los Angeles, Texas, and elsewhere go unused every day. The US could immediately do hundreds of thousands more tests if so inclined. So why isn't it?

We're still operating on the mindset of a testing scarcity," says Jha. Though capacity has improved, he notes, most states either haven't eased up restrictions against testing people with mild or no symptoms, or haven't encouraged more of those people to seek testing. Instead, many communities have simply elected to open their economies back up-even New York City, the epicenter of the pandemic in North America. The US is now seeing a surge of new cases.

Not every health expert is gung-ho about mass testing. Michael Hochman, a physician at the Keck School of Medicine of the University of Southern California, thinks we could get by with the current level of 500,000 a day. He wrote an op-ed in Stat last month arguing that there are some downsides to mass testing, including the cost, the potential for infection to spread at testing sites themselves, and the concerning prospect of false negatives. He would prefer to limit testing to the symptomatic, and instead have communities maintain a greater focus on simpler day-to-day habits like social distancing, wearing face masks, washing hands frequently, and keeping surfaces clean. Places that have managed the virus well, like South Korea, Taiwan, Japan, Iceland, and Hong Kong, have had successful testing programs, but he thinks the reason they're now able to open up their economies more widely has more to do with how they made face masks the norm.

Michael Mina, an epidemiologist at Harvard University, says we certainly need more testing, but he adds that viral testing is most important at the beginning of a pandemic, when cases are spiking and it's critical to find and isolate those who are infected. Later on, he says, we don't necessarily want to be testing everyone if viral presence is low." That's when serological testing, which looks for the presence of antibodies indicating a previous infection, can provide a better sense of how the epidemic is trending in a community in the long run and whether it's safe to open things up again. Mina also suggests that the additional testing capacity will be more valuable in the fall, when an expected second wave of infections hits the US.

But even if you think current testing levels are fine for now, there's an argument to be made that we're wasting this untapped capacity if we just wait until the second wave hits.

Rethinking the role of testing

Kiessling is one researcher who has seen how testing facilities are being underutilized. Every Tuesday for the last six weeks, the First Parish Unitarian Church in Bedford, Massachusetts, hosts a covid-19 testing clinic administered by her lab. As a local lab with a smaller operation, Kiessling believed she and her team at BRF would be able to return test results to people in under 48 hours, versus the 7 to 14 days many people around the country have been forced to wait.

Early on, the testing site was getting upwards of 100 people. Numbers have since decreased bit by bit. When I went, on June 16, only 30 people were registered, and a few didn't even show up. At full capacity, the lab could be running 200 tests a day, but it rarely meets those limits these days.

HARRY HOW/GETTY IMAGES

Why have numbers plummeted so drastically? We don't really know why," says Ryan Kiessling, BRF's operations manager. It seems to be fatigue." That's probably a pretty good theory. According to a Gallup poll this month, many Americans think the situation in the US is getting better. With more businesses and more recreation areas like beaches opening up again, people are more willing to let their guard down and abandon the wearying habits they've kept up for several months: they are increasingly resuming regular activities, and the number of Americans practicing isolation dropped from 75% to 58% in May. And that also means they may view testing with diminished importance. People are just feeling really tired about anything that has to do with covid at this point," he says. They just want it to be over, even though it's not."

It's easy to understand that people want to go back outside. It might also be easier to accept if we were taking advantage of all the testing capacity at our disposal. Ann Kiessling thinks we could test people regularly (at least every 14 days) to ensure they're safe to go back to work or school, and get results fast enough to isolate them immediately if it turns out they're infected.

This isn't exactly a brand-new idea-many employers are already looking into mandatory regular testing for employees to open offices back up. But she wants to take this idea a step further, and use testing as a means to soften social distancing rules in certain situations.

For example, let's say a school or day-care center wants to reopen. It's going to be extremely difficult to maintain stringent social distancing in these types of settings. But one solution could be to mandate that all employees and all children enrolled be tested regularly (perhaps multiple times a week) and rigorously monitored for any potential symptoms. This could make it possible to safely open these places back up. And it could be accomplished with all the extra testing capacity sitting idle right now.

If done carefully, such a plan could work in offices too. Social distancing is very important to stopping the spread of the virus, and we don't want to ease those requirements on a whim. But, says Kiessling, if you're working with a small group of the same people, and your job doesn't require you to interact face to face with strangers, regular testing might lower the level of risk to a point you and your coworkers find acceptable.

But the Massachusetts health department and the state's local boards of health have not revised their guidelines to make testing part of the strategy for reopening businesses or schools. Kiessling says she's brought it up quite a few times with state and local health officials, especially at the behest of several businesses that simply can't operate under current social distancing requirements-to no avail. Officials simply seem uninterested in trying to expand the role of testing. It's stupid," she says.

Rethinking how we use excess testing capacity might be a moot point in a few months anyway: when the weather gets colder, the virus is expected to hit hard again, and many areas could be overwhelmed as they were in March and April. The system could be pushed to its limits once more.

Jha suggests that if capacity becomes scarce again, we could stretch it out with strategies like pooling, in which test samples from multiple individuals are processed as a single assay: if it's positive you have to go back and retest the samples one by one to see who's infected, but if it comes out negative, you can rule out infection for many people all at once. Ultimately, though, he is concerned. If we're really stuck at testing numbers of around 400,000 to 500,000 a day," he says, it's going to be very hard for us to do anything useful in terms of keeping this virus under control."