“If you’re going to be traveling, if you’re going to be in a situation where you might be exposed to others or where you can protect others by quarantining yourself, right now is the time to do it and to do it carefully because this is when it can be especially effective” -Jeffrey Townsend
Quarantines are an effective way to stop the spread of the coronavirus but they have been one of the most difficult and confusing parts of the pandemic. New research shows how people exposed to the coronavirus could cut their quarantine in half if it is paired with a test at the right time. This episode looks at this research and how it prevented an outbreak on an offshore oil rig.
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Jeffrey Townsend:It is really important right now to pay attention to this kind of quarantine issue. If you’re going to be traveling, if you’re going to be in a situation where you might be exposed to others or where you can protect others by quarantining yourself. Now is the time to do it and to do it carefully because, uh, this is when it can be especially effective.
Celine Gounder: Hi, you’re listening to EPIDEMIC, the podcast about the science, public health, and social impacts of the coronavirus pandemic. I’m your host, Dr. Celine Gounder.
Roxanne Khamsi is a science reporter based in Montreal. Like all of us, Roxanne missed out on a lot of big life events this year because of the pandemic. The demands of quarantine have become a major issue for her.
Roxanne Khamsi: Here in Canada, I can’t go visit my sister in Colorado and come back without sitting at home for 14 days. And I’m not allowed to go to the grocery store and I’m not allowed to, you know, like walk a dog. If I had a dog, I can’t really can’t leave the house.
Celine Gounder: The word quarantine goes all the way back to the Middle Ages. Back then, the disease people were worried about was the plague. So, the city of Venice started requiring ships to anchor in the harbor for 40 days before they could come ashore to prove they didn’t have the plague. The word quarantine comes from the Italian words for “forty days.” Makes a 14-day quarantine sound easy, right?
But quarantine rules in Canada are serious. People are ordered to quarantine in their homes for 14 days after they return from abroad. There are big fines if someone doesn’t comply. Fines as big as a million dollars.
Roxanne Khamsi: I mean, it’s a million dollars Canadian, so it’s a little less [laughs].
Celine Gounder: All the same, that’s still a lot of money. And if those fines weren’t high enough, someone who violates their quarantine and infects other people could get jail time too.
Roxanne Khamsi: It’s definitely,, uh, something that people here take really seriously. And I think that my friends in the States don’t understand that like a lot of them are surprised when I’m like, guys, it’s actually like a serious quarantine here for 14 days.
Celine Gounder: Even if you don’t get a fine or jail time, quarantines are an important part of reducing the spread of coronavirus. But quarantining has been one of the most difficult and confusing parts of the pandemic. There are different rules for every country and even every state here in the USA. And it takes a toll on people.
Roxanne Khamsi: A lot of people have jobs they have to go to where they can’t quarantine and 14 days just seems so cumbersome that they just throw their hands up and say, it’s not possible. It’s cumbersome in practical ways. And then also kind of emotional ways to stay at home for 14 days is a lot.
Celine Gounder: In the end, Roxanne decided that seeing her sister’s new baby wasn’t worth the hassle.
Roxanne Khamsi: And so I didn’t go see her and her new baby, this fall, and I maybe would have if it was only eight days.
Celine Gounder: But what if you could get all the public health benefits of a quarantine in eight days… or even less?
Back in October, Roxanne wrote an article about some new research that caught my attention.
Roxanne Khamsi: A biostatistician that I know reached out to me and said that his group was working on this new way of thinking about quarantine, and they’d done some calculations to suggest that quarantine didn’t need to be as long.
Celine Gounder: That research is still under peer review at this recording, but it caught the CDC’s attention, too. This month, the agency cited the pre-print in its updated quarantine recommendations. The CDC now recommends a 10-day quarantine without a test… or … as little as seven days if — and only if — someone tests negative on day five or later.
In this episode we’re going to look at how quarantine for coronavirus could be cut by as much as 50% when combined with testing at just the right moment. We’ll speak with the researcher whose work was cited by the CDC, and, we’ll find out what an oil rig has to do with all of this. Today on EPIDEMIC… a smarter way to quarantine.
The biostatistician Roxanne wrote about this fall is Jeffrey Townsend.
Jeffey Townsend:I’m the Elihu Professor of Biostatistics at Yale University, specifically in the Yale school of public health.
Celine Gounder: Before the pandemic, Jeffrey used his skills to do things like help oncologists estimate the growth rate of cancer in the body.
Jeffrey Townsend:I’ve always been someone who really likes that connection between the math that I’m doing and the real world.
Celine Gounder: So when the pandemic arrived, Jeffrey shifted his attention to COVID. He set out to see if an effective quarantine could be done in less than 14 days.
Jeffrey Townsend: Quarantine in principle should be able to be shortened. But how much was a question that no one seemed to know the answer to and it seemed something that was approachable from a mathematical perspective. Uh, so we decided to address that question.
Celine Gounder: Jeffrey thought testing could be the key. His model came up with two major findings.
Jeffrey Townsend: One of the things that, became very clear as we did the modeling was that, uh, testing on exit from quarantine was, uh, far better approach than testing on entry to quarantine. And then another thing that we found was just that you could significantly shorten the quarantine by doing that kind of exit testing
Celine Gounder: Why might you miss somebody upon entry into quarantine? Why might they test negative?
Jeffrey Townsend: Yeah, the easiest way to think about this is just to think a little bit about the biology of the disease. When the virus actually infects you, it probably doesn’t infect a very large number of cells at the beginning. It probably infects a very small number of cells. So the point is during that very early phase often called the latent phase. When the virus is hardly producing very much virus, you’re not very infectious, but it’s also very hard in that early latent phase for the test to come out as positive and indicate that you actually have the infection.
Celine Gounder: So someone could be infected and have the virus multiplying inside them, but not have enough virus in their system when they’re tested to get a positive result.
Jeffrey Townsend: That means that we have to be extremely careful about trying to catch this disease early. And that’s also why we sort of need to combine the test with a quarantine.
Celine Gounder: Jeffrey’s model predicted that that tipping point for the virus was somewhere around day seven of infection.
Jeffrey Townsend: Past five days you’re gaining some benefit to six and seven. As you get to more days — eight, nine, 10, 11, 12, 13, 14 — you are gaining benefit, but it’s getting to be smaller and smaller benefit with each extra day.
Celine Gounder: Basically, the vast majority of people who are infected with the virus will test positive by about a week after exposure. So, after waiting this period of time… and then testing to verify if there’s an infection… would give you actionable results without someone waiting the full fourteen days.
Jeffrey Townsend: Industry immediately took interest because they have a major economic incentive to try to understand this issue.
Celine Gounder: Specifically, oil companies. BHP is an Australian oil company that operates offshore oil rigs around the world.
Jeffrey Townsend: They really want to avoid any kind of sickness and, and God forbid, an outbreak on those rigs because they would probably, if they had a full scale outbreak have to shut down the entire rig, which would cost enormous sums of money.
Celine Gounder: The stakes were high for BHP. An offshore oil rig is not something that turns on and off like a light switch. The company needed to keep their workers safe and maintain their operations.
Jeffrey Townsend: And, uh, we started collaborating with them and giving them some of our results uh, early on at the same time, they shared some of the data that they got. And that was a great opportunity for them to learn from us and for us to learn from them.
Celine Gounder: So what happened when Jeffrey’s model got tested on an oil rig? We’ll find out after the break.
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An offshore oil rig sounds like an environment that’s pretty far removed from most people’s everyday life. But Jeffrey says it was an ideal environment to test their model.
Jeffrey Townsend: It’s really valuable to us that it was an oil rig because we know there were no outbreaks on the oil rig because it’s a closed population.
Celine Gounder: BHP tweaked Jeffrey’s model.
Jeffrey Townsend: Which is not exactly surprising. It’s not like we did a cost effectiveness analysis, which is ultimately what they need to figure out is how? You know, what are the costs of doing these things in terms of their personnel? What did their personnel want? There’s a lot of operational questions that are not within the academic question that we asked. They decided to sort of accept that and look at that and say, okay, well, if most of the marginal returns are obtained by, uh, having at least four days, what we’ll do is we’ll do a five-day quarantine. We’ll test at 96 hours. And then if they come out positive, then we will send them off, off shore.
Celine Gounder: BHP tested people at the end of quarantine… but they also tested their employees at the beginning. If someone was already showing signs of the virus, the company needed to isolate them and find a replacement fast.
Jeffrey Townsend: But that also provided a really nice test dataset for us to examine our results because then we had individuals who were tested on entry and we could observe if any of those individuals who tested negative at entry were testing positive at 96 hours.
Celine Gounder: Remember, these are people who tested negative at the beginning of their quarantine… and then got tested again when they were getting ready to leave for the rig.
Jeffrey Townsend: There was quite a few people who were caught by that second, um, exit tests. And because they were, uh, found to be infected during that exit test, they were not sent offshore and that is estimated by our analysis anyway, to have prevented as many as nine outbreaks that might’ve occurred.
Celine Gounder: Jeffrey says knowing his research helped people was exciting.
Jeffrey Townsend: I mean, it was so awesome because for academics, most of the time, we don’t really get to see almost in real time, our work applied to actually prevent a disease for instance. It usually takes years for a policy recommendation to be adopted by some regulatory authority, et cetera. But I think the thing that really brought it home the most was when they told us that they were telling other members of the industry how great their safety record was. So, um, you know, when industry starts bragging to other parts of industry about something, you know, it’s good because [aughs] that’s mostly meant as a, you know, that there’s not really a lot of reason for them to do that except for out of pride.
Celine Gounder: So what are the implications here for the general public in terms of how they should be thinking about testing?
Jeffrey Townsend:I think for the general public, uh, the point would be,if you think you might be encountering a risk situation by going somewhere by visiting relatives, whatever you’re doing, then it behooves you to have a quarantine period before you go to visit them. If you can have that quarantine period to be about a week long, ideally even longer, if you can, but a week long, we’ll get you most of the benefit. And then that test at the latest point you can, where you’ll still get the information about the test before you have to go and expose those individuals that you care about. Nothing is guaranteed in this world, but that means you’re really limiting your risk considerably if you’re doing that.
Celine Gounder: Consistency in messaging has been a big problem during the pandemic. Roxanne Khamsi says the different rules in different places make people feel like quarantine and other public health recommendations are arbitrary.
Roxanne Khamsi: And I think what is going to happen is that public trust in these rules is going to erode because there’s so much back and forth and so much contradiction.
Celine Gounder: Roxanne thinks research like Jeffrey’s could help establish a common set of rules for how quarantine recommendations should be made.
Roxanne Khamsi: I think it’s important for, for public health officials to now talk to one another and to say, Hey, let’s be on the same page about this. Why, why should there be a 48-hour quarantine in one place and a four-day quarantine in another and a 14 one in another. I think that what needs to be done is like a kind of convening and like almost like a evidence-based approach to quarantine rather than what seems to be happening, which is like, what businesses think might be most logical or, you know, what the public is most easily convinced to do, which is not necessarily always the best thing to do.
Celine Gounder: But there are also limits to how this information could be scaled to the broader population.
Roxanne Khamsi: They’re kind of operating in like an ideal scenario where testing isn’t a rate limiting factor, but as you’re very well aware, testing certainly in the real world, not something that’s abundantly available as much as it should be and the results don’t come back as fast as they should. So, I think that’s a really, really good criticism and question about how to apply these findings.
Celine Gounder: Testing capacity has been a stubborn problem since the beginning of the pandemic. How can we implement these suggestions when turnaround times are slow and tests are still hard to come by?
Jeffrey Townsend: The answer to both of those questions, unfortunately depends on how well we do everything else in this pandemic. The ability to have fast turnaround and the ability to have enough testing capacity to do this on a large scale, depends on our ability to get the currently out-of-control epidemic into control.
Celine Gounder: And there’s a lot everyone can do to make that happen. They’re the same basic public health recommendations we’ve been talking about for months: wear a mask — keep at least six feet apart from others — avoid indoor gatherings.
Jeffrey Townsend: If we want to have the capacity to try to maintain that economic activity and the health and safety of those individuals who are at high risk, then everyone else needs to keep this epidemic at a low level so that it enables us to apply those tests in the right place and to have the test turnaround that is necessary.
Celine Gounder: This podcast was released on December 11th. This week, the United Kingdom started distributing the Pfizer vaccine. Canada became the second Western country to approve Pfizer’s vaccine. And the FDA found the same vaccine to be safe and effective. So, as the vaccines start to roll out, what will be the role of quarantines in the coming months
Jeffrey Townsend: It is fantastic news that these vaccines appear to have very high efficacy. However, we need to be very cautious about that as a public health message, because the very high efficacy of the vaccines in clinical trials does not at this point, translate to any benefit whatsoever to individuals who are out there now.
Celine Gounder: It could take many months before enough people are vaccinated and the pandemic is under control. Jeffrey says this holiday season — as cases and deaths continue to spike — being thoughtful about quarantining could be more important than ever.
Jeffrey Townsend: In fact, right now we really need to do everything we can to exercise this kind of restraint on social interactions, social gatherings, where we’re seeing most of the transmission happening. It is really important right now to pay attention to this kind of quarantine issue if you’re going to be traveling, if you’re going to be in a situation where you might be exposed to others or where you can protect others by quarantining yourself. Now is the time to do it and to do it carefully because this is when it can be especially effective and when it is important to do it.
Celine Gounder: EPIDEMIC is brought to you by Just Human Productions. We’re funded in part by listeners like you. We’re powered and distributed by Simplecast.
Today’s episode was produced by Zach Dyer and me. Our music is by the Blue Dot Sessions. Our interns are Tabata Gordillo, Annabel Chen, and Bryan Chen.
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I’m Dr. Celine Gounder. Thanks for listening to EPIDEMIC.