A new episode of our podcast, “Show Me the Science,” has been posted. At present, these podcasts are highlighting research and patient care on the Washington University Medical Campus as our scientists and clinicians confront the COVID-19 pandemic.
Most of the country is relaxing guidelines put in place to stem the spread of the novel coronavirus. But many questions arise about how to re-open safely. In this episode, we discuss making everyday life safer with Hilary M. Babcock, MD, a professor of medicine in the Division of Infectious Diseases and medical director of the Infection Prevention and Epidemiology Consortium for BJC HealthCare. She says masks, physical distancing and good hand hygiene remain important.
Another important aspect of opening safely involves testing to identify who has and who has had COVID-19. Antibody testing that might identify who already has been infected and might have some resistance to future infections was long viewed as something of a silver bullet, and as the country re-opens, many clinics now offer antibody testing. But it’s not clear if those tests will make us any safer. Neil W. Anderson, MD, an assistant professor of pathology and immunology in the Division of Laboratory and Genomic Medicine, and Christopher Farnsworth, PhD, an instructor of pathology and immunology, are directing the antibody testing effort in the laboratories at Barnes-Jewish Hospital. They say that the antibody tests may not be accurate enough to help make opening safer.
False positive results are cause for concern
The podcast, “Show Me the Science,” is produced by the Office of Medical Public Affairs at Washington University School of Medicine in St. Louis.
Jim Dryden (host): Hello, and welcome to “Show Me the Science,” a podcast about the research, teaching, and patient care as well as the students, staff and faculty at Washington University School of Medicine in St. Louis, Missouri, the Show-Me State. My name is Jim Dryden, and I’m your host this week. We’ve been focusing these podcasts on the COVID-19 pandemic and Washington University’s response. This week, with some level of reopening underway in all 50 states, we look at how to try to do that safely. Washington University infectious diseases specialist Hilary Babcock says it’s less a matter of whether certain things are safe or not, and more about all of us doing what we can to make things safer.
Hilary Babcock, MD: Things that are lower risk are things with fewer people, things that are either outside or in large spaces. So outdoor activities, large spaces, good physical distancing, all of those things are signs that what you are doing or where you are going is safer.
Dryden: In addition, for months we’ve heard how valuable more testing, particularly antibody testing, would be as we try to reopen. But many of those tests give a high percentage of false positives, and it’s not clear yet how long people might be immune to future infection even if testing shows that they have had COVID-19. Chris Farnsworth helps direct the antibody testing efforts now available at Barnes-Jewish Hospital in St. Louis.
Christopher Farnsworth, PhD: That’s what a lot of the general public will be interested in, is knowing, “I was sick a month and a half ago and I wasn’t able to get a molecular test, so did I actually have COVID or didn’t I?” And I do think that it’ll be useful for a lot of people in that way.
Dryden: But it won’t necessarily help people know they’re safe moving forward, and a few months ago, safety was the whole point of closing things and trying to keep people at home. Originally, we were told the country could begin to reopen when infection rates clearly were falling. But Hilary Babcock says that’s not the case in many states, even though things are reopening.
Babcock: So I think there are still risks. The virus is not gone. The reason that some places are moving toward reopening are reflecting the difficulties of keeping people home for months on end, the impact on the economy. So I think those are the main drivers, and what we need to balance that with is safety practices that can make it safer for all of us. And so the practices that we’ve been talking about all along as being important become even more important during this time as we’re able to be a little bit more out and about. And those practices include wearing a mask all the time when you’re out and around other people; as much as possible keeping six feet — at least six feet — of distance between yourself and others. And that includes when you are wearing the mask and when the other person is wearing a mask, and that also includes staying home yourself if you are ill. And then hand sanitizer and washing your hands a lot just remains a really important practice as well.
Dryden: Yeah. As an allergy sufferer, I love waking up about two days a week with a slight sore throat and wondering whether it’s allergies or not.
Babcock: Take the Claritin, and if that goes away you’re probably fine, and if it doesn’t, then you may not be fine, and you should think again.
Dryden: Now, other than grocery stores, pharmacies, restaurants for takeout, a lot of us really didn’t have any experience of going out during the first several weeks of the lockdown. Now you can get a haircut, fly on a plane. How risky are some of those activities?
Babcock: The risk is variable, and so I think we can define things that are higher risk and things that are lower risk, and then we continue to rely on those same practices during all of these settings. So things that are lower risk are things with fewer people, things that are either outside or in large spaces. So outdoor activities, large spaces, good physical distancing, all of those things are signs that what you are doing or where you are going is safer. Places where it’s harder to maintain that distance, enclosed, tight indoor spaces, are higher risk.
Dryden: I’ve got a yellow lab, walk him around the neighborhood, and I seem to see a lot of people who maybe think we’ve turned a corner. I see furniture movers with no masks. I see construction workers sharing tools. I see people sitting close together over a cup of coffee at a Starbucks up at the corner. Those behaviors are still risky, right?
Babcock: They are. I do think that it’s hard for us, walking our dogs and seeing these interactions, to know the whole situation, necessarily. So if those two people sitting together at a Starbucks table are a mom and daughter or a wife and husband or partners that live in the same household, then they’re not really at higher risk at a Starbucks table than they are at home. Similarly, I personally would want movers coming in and out of my house to be wearing masks, and I would think that they would want to be wearing masks to protect themselves from each other. People sharing construction tools, as long as they’re doing hand hygiene on a regular basis, are probably OK. So I think there’s a lot that goes into really assessing the risk of these individual interactions that we may witness.
Dryden: Restaurants, gyms, churches. Now, I’m not talking about the pictures we saw of the people in the pools at the Lake of the Ozarks a couple of weeks ago, but in a restaurant or working out in a gym, in a church, you’re spending significant amounts of time at an indoor location. People talk; they sing; they breathe heavily while they’re on the treadmill. What about places like that? Are those safe at this point?
Babcock: So I think a lot of that depends on the measures that those different institutions have put in place to keep their members safe. Gyms that have bikes and treadmills that are at least six, maybe 10 feet apart; that they have wipes by every piece of equipment so that everyone can wipe it down before they get on, wipe it down when they get off; asking at the door about symptoms or temperature screening, things to be sure that people who are sick are not coming; all of those things can make that space safer. Churches similarly can keep people spaced out and have recommendations for family groups to sit together, but to have significant space between groups; to not have singing of hymns by the congregation, but maybe just have a soloist who sings from the front of the church; and have hand sanitizer available to everyone on their way in. And then I think every person and family just has to do sort of their own risk assessment. Does that situation seem safe for you and your family? And you kind of have to balance that for yourself.
Dryden: One of the things that we talked about a lot at the beginning of this was how, once we had some testing in place, we’d be able to reopen things more successfully. And now there is much more testing available than there used to be. There’s antibody testing; there are other kinds of rapid tests that are being developed. Is that enough?
Babcock: The direct value of testing for being able to open a business, for example, I think is still not very clear. The tests are a snapshot in time, and they don’t tell you what your status will be three days or five days or a week later. But I don’t think that they’re sort of a silver bullet to, say, if we tested everybody every day. And everyone who’s actually had one of these tests mostly doesn’t want to try and think about having one every day. There is a lot of work trying to look at other ways to do the tests, but the nasopharyngeal swab is the one we fondly refer to as the brain biopsy. That’s a pretty uncomfortable swab way back to the very back of your nose. But there’s work going on trying to figure out whether we could just use saliva, and if people could spit in a tube and get highly accurate test results. That would be a real game changer in terms of availability of testing and ease of testing for bigger populations.
Dryden: She’s talking primarily about so-called molecular testing that looks for traces of the virus to help doctors diagnose an active infection. But what about antibody testing or, as it’s also called, serology testing for COVID-19? Those tests are supposed to reveal not the presence of the virus itself, but rather evidence that the body has mounted a defensive response to fight the virus. Antibody testing is available now at a lot of places. To learn more about how those tests might guide reopening, we went to an assistant professor and an instructor in the Department of Pathology & Immunology at Washington University School of Medicine, who also happened to be working with antibody testing in the laboratories at Barnes-Jewish Hospital in St. Louis.
Neil Anderson, MD: I’m Neil Anderson. I’m assistant medical director of clinical microbiology here at Barnes-Jewish. I’m also the medical director of the Molecular Infectious Disease Laboratory.
Farnsworth: And my name is Chris Farnsworth. I’m an instructor in pathology and immunology and the medical director, one of the medical directors, of the core lab at Barnes-Jewish Hospital.
Dryden: Is antibody testing used to diagnose COVID-19 while someone is still sick? Or is this a test that tells you someone has been sick? What does it tell you exactly?
Anderson: Using antibody testing to make the diagnosis of COVID-19 is one of the things that people are hoping to be able to do.
Dryden: This is Neil Anderson.
Anderson: However, there’s some pretty big caveats to using it to diagnose a newly infected person. What we have found in our internal data is that if you test someone who has only been symptomatic for about three days, we have a sensitivity of less than 10%.
Dryden: That means less than 10% of the tests would be accurate.
Anderson: Basically, it’s because your body takes some time to make these antibodies. So in the early days of illness, they’re just not going to be there.
Farnsworth: Another really important caveat to that that I’ll add is that …
Dryden: This is Chris Farnsworth.
Farnsworth: … people that are immunocompromised, it’s not immediately clear yet as to if they’re going to make an antibody response. So it definitely wouldn’t be useful in some of those populations to try to diagnose an infection.
Dryden: But it would be potentially useful if someone was sick, was not tested, now they’re better, to test them to see whether it was this that they had or maybe some other upper respiratory disease?
Farnsworth: I’m not sure if that’ll be its main use, but I think that’s what a lot of the general public will be interested in, is knowing, “I was sick a month and a half ago, and I wasn’t able to get a molecular test, so did I actually have COVID or didn’t I?” And I do think that it’ll be useful for a lot of people in that way. It’s not really going to change at that point from a health-care standpoint, how we’re going to treat those people. They’ve probably already recovered. Still, we’ll perhaps be able to know a little bit better what our prevalence was epidemiologically. But by and large, it’s not going to be helpful from a medical standpoint. Would you agree with that, Neil?
Anderson: Yeah. Absolutely. I think there’s a couple things to keep in mind there. If someone’s wanting the test just because they’re curious or they want peace of mind, one of our central tenets in all laboratory testing is we try not to perform testing unless it’s going to somehow be acted upon or of benefit to the patient. And you can also find out some information that it might do the opposite of giving you peace of mind. For example, with COVID serology testing, we know it’s not entirely accurate. We know patients can have false positives, and we know people can have false negatives, particularly early on in the disease. So you might be getting the test to give yourself some peace of mind, but if you end up with a bad result from a bad test, it could do the opposite of that.
Dryden: Well, but if I am tested for a good medical reason and it’s positive, but I’m not currently sick, does that mean it’s safe for me to go back to work? Does it mean that I’m no longer sick and that I can’t transmit the virus?
Anderson: So I believe what you’re alluding to is this conception that some people have that being serologically positive means you are now immune to the virus. Unfortunately, at this point, we do not know, nor can any of the assays currently predict with accuracy, immunity. Right now, to be positive on one of these assays means you have been exposed to the virus, and you mounted an immune response. Whether that immune response is enough to stop you from getting infected again, we frankly don’t know, and no one really knows at this point. Since we’re – even though it doesn’t feel this way – we’re relatively early on in this pandemic, we don’t have the outcome data to make those claims.
Farnsworth: So one of the things that we’re most concerned for is a false positive result. And that’s just kind of based on how we think clinicians and people will try to use the tests. We really don’t want false positives giving someone the idea that they’re fully protected and they can go back to work and not have to worry about being exposed to the virus anymore.
Dryden: This also may be able to detect who would be eligible to be, say, a plasma donor whose plasma is being used to treat some of those with severe COVID infection?
Anderson: That is one of the potential uses for this test. That is correct. However, there are some limitations with that, too. It’s not a test that gives you a strength of positivity. So as far as identifying someone who has more antibodies versus someone who doesn’t, it can be difficult to use one of these tests to figure that out.
Dryden: Now, the commissioner of the FDA, Stephen Hahn, has said that whether a test should be used as a ticket for someone to go back to work, if that test is the sole item, he says his opinion for that would be no. Do you guys agree with that statement?
Anderson: I would say that when we talk about serology testing in general, oftentimes when we’re taking something that’s indirect, like a measurement of your immune response to a virus, there are so many pre-analytical factors that could lead to false positives or erroneous results. Or maybe not even erroneous, but you were exposed to something a long time ago. Serologic results should always be interpreted in the entire clinical context of the patient, meaning anyone who’s relying just on a serological result to make a clinical decision really needs to rethink that. And I think COVID-19 is really no exception there. The testing that we are providing regarding serology has the potential to be useful, but it’s always going to have to be interpreted with the rest of testing.
Farnsworth: In Missouri right now, COVID-19 is still most likely a low-prevalence disease, at least by molecular testing. So from a lab-testing perspective, what that means is that if you were to run all of Missouri through an immunoassay, even one with really, really good specificity, you’re actually going to get far more false positives than true positives.
Dryden: In other words, antibody testing probably isn’t what’s going to make reopening safe. Meanwhile, in the midst of reopening, we’ve now seen thousands out protesting. A few weeks ago, many of those same people were only venturing outside for a walk or to get groceries. Babcock says predicting the effects of these protests is tricky.
Babcock: And so I think it’s really important just to balance different competing priorities. And certainly COVID is a public health crisis that has been going on for several months now, but systemic and structural racism and police violence against communities of color are also public health crises that have been going on, honestly, longer than COVID has. So I don’t think we should try to use the COVID outbreak in any way to try to discourage the protests that are occurring and the desire and need for people to stand in opposition to those critical problems. I think it’s great to see as many people that are out wearing masks. Outdoor environments are generally safer than indoor, more enclosed environments. People who are going out for the protest can do the same kinds of things that we’re talking about. They can wear masks. There have been protests where people are sitting or lying on the ground, and they are distancing as much as they can, and so those kinds of practices are helpful as well. And as the police and others are responding to protests, allowing the space for the protesters to keep that distance is also helpful, so trying not to corral people into small spaces. All of those practices together really will have an impact on the kinds of case numbers that we might see from this. But I think it’s going to be hard to know. We have also opened our communities. We had Memorial Day celebrations; we saw lots of people getting together. So being able to specifically point to the protests more than other social interactions and events, I think, would be difficult to really be clear about.
Dryden: Babcock says she will be keeping a close eye on infection rates over the next few weeks. Meanwhile, Anderson and Farnsworth will keep running tests to gather more information as they attempt to make current testing as accurate and helpful as possible. And we at “Show Me the Science” plan to take a closer look at some of the ways that race has become involved with COVID-19, looking at some of the groups most at risk, along with some of the reasons why. “Show Me the Science” is a production of the Office of Medical Public Affairs at Washington University School of Medicine in St. Louis. The goal of this project is to keep you informed and maybe teach you some things that will give you hope. Thanks for tuning in. I’m Jim Dryden. Stay safe.