Listen: Is Faster Better?

We want vaccines. We want rapid tests. But when is fast too fast?

The federal government is telling states to prepare for a vaccine as early as November. But a major trial has been put on hold. On this episode of Social Distance, James Hamblin and Katherine Wells look to staff writer Sarah Zhang for answers—and updates on a vaccine.

But before a vaccine arrives, is testing our best hope? Staff writer Alexis C. Madrigal joins to explain “rapid testing.” New methods could massively increase the number of tests, but are there obstacles to these breakthroughs making a difference?

Listen to the episode here:

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Here is a transcript of a portion of their conversation with Alexis C. Madrigal, edited and condensed for clarity:

Katherine Wells: Of course, a vaccine is the way out. But the vaccine’s not coming anytime soon, at least in a widespread way, regardless of how fast we can get it done. Testing is the middle option. Testing is the way we can manage this situation until there is a vaccine. Is that true? Would testing allow us to get this under control?

Alexis C. Madrigal: It is the thing that I can imagine doing that. Whether or not that happens is slightly different. In the good scenario for testing, it is something that can help a lot. It probably isn’t going to be enough on its own, but it can help a lot. Testing is going to be a big part of any way back to normalcy.

Wells: Let’s start with the optimistic scenario.

Madrigal: What people are trying to develop right now are faster tests, something on the order of a few minutes. They’re inexpensive paper-strip-type tests, more like pregnancy tests. And [they] would decentralize testing radically so you wouldn’t have to go to a testing center. You would just be able to buy these things at retail or maybe go to a testing kiosk.

Wells: Is this, like, you just spit on a paper strip and it turns a color?

Madrigal: Yeah, or you swab your nose … It’s an easy test. It’s a fast test. And it’s a cheap test. Instead of costing from $10 to $150, it costs from $2 to $10.

James Hamblin: Are people already using prototypes of this sort of testing?

Wells: Is this what they have at the White House?

Madrigal: Such tests exist in some places. [The health-care company] Abbott quite famously says they’re going to produce 50 million of these tests in the month of October. And a variety of other companies are also working on similar things. What the White House has been using primarily are similar, but instead of a little paper strip, there’s a little desktop machine and a testing pod that you put into the machine. People have been calling them “point-of-care tests.”

These tests look for antigens instead of trying to find direct evidence of the genome of the virus, for RNA. They are faster, but they have two problems. They’re less sensitive, which means you’re less likely to catch every positive. They’re also less specific, which means that if you really deployed them at scale, you’d be likely to actually create a lot of false positives. And there are different camps of people who are worried more about one problem or more about the other.

Hamblin: In a screening test, you don’t mind some false positives. You can send people to go get [a more accurate PCR test] if they’re positive on this test. And theoretically, that would be efficient. But it’s the false negatives that can render a screening test actually worse than nothing.

Madrigal: This had been my thought about it. Really interestingly, some of the major proponents of the test are the ones most worried about the false positives. Because the numbers are supposed to be so huge. Let’s say you’re doing a million tests a day with these—which is really what Abbott is promising very soon to be able to at least have the capacity to do—you could be generating close to as many false positives as total positives right now on PCR tests.

Hamblin: That’s a lot.

Madrigal: Right? It’s because the scale of it is so enormous, particularly if they’re deployed in very low-prevalence areas where there’s really not a ton of virus. And people are worried that that may snarl the various testing systems. And also, people might lose faith in using these tests if they think the chance of a false positive is so high.

Wells: I know what the world looks like right now with somewhat limited and sporadic testing, with test results that can take anywhere from a day to two weeks. What would the world look like if we were doing a million rapid tests a day with an uncertain number of false positives?

Madrigal: And an uncertain number of false negatives, like Jim was saying. Well, I think the mega-happy scenario would be that, in that big dragnet of screening, you would catch enough contagious people that you would start to really bring down the rate of transmission. One of the things that I’ve been thinking about from watching these numbers all the time is that, with our current set of strategies, we tend to do a pretty good job at bringing the rate of transmission down to, like, around 1.

Wells: And by “1,” you mean the average number of people that someone is passing it on to. Right now, each person on average passes it to one other person.

Madrigal: Exactly. And so, we can’t really get to truly suppressing the virus and back to normal life. But also, most places are not actually also seeing huge runaway outbreaks. And when places do a lot of the things that every public-health person says to do: mask, wash your hands, social distance, avoid large gatherings … all that stuff appears to get us down to around 1.

And so we’re kind of balanced on this knife edge where we’ve had a pretty hard time getting to suppression the way that Asian countries have. But we’re also not getting torched all the time. And so what I would hope testing would do, in the happy scenario, is be the thing that helps us start to drive way lower than one 1.

Wells: Would that look like: I wake up every morning and I test myself?

Madrigal: The way that it would start to roll out first—and the way that it almost certainly will with the Abbott test called BinaxNOW, their first very simple test—would be workplaces and schools. These are tests that could be done by a school nurse. It’s kind of unclear whether they’re going to be rolled out straight up for screening, like you’ll just go into the Ford plant and once a week you’ll do this test.

One of my sources said, “You know, we’ve been peddling testing strategies for months and without the ability to do lots of tests.” And no one cared. Now, suddenly, there’s this idea that maybe there’s going to be all these tests available. And now people are scrambling to put together strategies. The kind of strategy that strikes me as most likely is some kind of regular testing, and testing within groups that sort of makes sense to test together. These strategies, which have kind of been on the shelf, will get rapidly developed … primarily, I think, by companies, nursing homes that are already supposed to be doing some of this kind of testing, high-risk workplaces, emergency responders … If that starts to work and suddenly there’s tons of tests, in this happy scenario, you will take a test a lot. Like, more than once a week. In a lot of the modeling that people have done, you need to get to sub-weekly testing for everybody. That means billions of tests a month.

Wells: And how many tests are we doing, for comparison?

Madrigal: Right now, we’ve never gotten to 25 million PCR tests in a month.

Wells: Is there any way that we could get to this scale with the more accurate, uncomfortable nose-swab test—the PCR tests that you send off to a lab?

Madrigal: I think, basically, no. The supply chains for all that stuff really started to break down at the end of July during the Sun Belt surge. In fact, testing peaked back on July 29. We are now doing more than 100,000 fewer tests on average per day now than we were then. And it’s a global market. Europe looks like it’s heating up again. So, we kind of tapped out PCR tests. This is going to be the way that we’re going to get to more tests and certainly more accessible and faster tests.

Wells: Faster, cheaper, more accessible, less vulnerable to supply-chain issues.

Madrigal: That’s the idea. That you can actually have more information more regularly. One of the things that people realized about the testing system that the U.S. built during the crisis-response phase was that it was more or less useless for contact tracing. You’re not getting results back for days and days. By the time you get the results back and they go send contact tracers out, it’s too late. You’ve already infected everyone you would have infected. It ended up being downright wasteful to do contact tracing. When you look at the U.S., we just have not had a lot of success with those strategies.

Wells: Every month there’s a new strategy that’s going to fix everything, and then it breaks down because of basically a lack of federal coordination and failures in all sorts of maybe expected ways.

Madrigal: We’re pushing these good ideas and these technologies through a flailing administrative state and through a federal health-care and public-health system that wasn’t really designed to do this. Even the stuff we do well, like technological development, is now coming up against bureaucratic—and I mean bureaucratic in a positive sense here—bureaucratic nodes and networks necessary to actually get something like this implemented. And of course, now we also have the election, which just adds this layer of fuzz around absolutely every single thing that’s happening.