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Podcast: New threats from highly contagious delta variant

This episode of 'Show Me the Science' focuses on how a variant of the COVID-19 virus is wreaking havoc in Missouri and around the country and what we can do to slow this new wave of infections

August 3, 2021

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A new episode of our podcast, “Show Me the Science,” has been posted. At present, these podcast episodes are highlighting research and patient care on the Washington University Medical Campus as our scientists and clinicians confront the COVID-19 pandemic.

As patients infected with the delta variant of the COVID-19 virus fill hospitals in parts of Missouri, and the virus spreads new infections around the country, Washington University data scientists and infectious diseases specialists are urging people to mask up again, regardless of vaccination status. The researchers say that although vaccination remains remarkably effective, masking and other public health practices that slowed the spread prior to the availability of vaccines are necessary again. Clay Dunagan, MD — a professor of medicine, senior vice president and chief clinical officer for BJC HealthCare and a member of the Metropolitan St. Louis Pandemic Task Force — says that as case numbers rise, public health measures have become more important. Dunagan and fellow infectious diseases specialist Hilary M. Babcock, MD, a professor of medicine and medical director of infection prevention and occupational infection prevention for BJC HealthCare, say that even if more people get vaccinated, it will be weeks before they are protected, and during those weeks, people will need to turn back to the practices that protected them before vaccines became available. Meanwhile, Philip R.O. Payne, PhD, the Janet and Bernard Becker Professor and director of the Institute for Informatics, associate dean for health information and data science and the chief data scientist at the School of Medicine, says computer models his team has created continue to predict a rapid increase in infections in St. Louis and in the surrounding area. And he says those models don’t show a peak yet, meaning we could be in the current wave of infections for quite some time.

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,” conversations about science and health with the people of Washington University School of Medicine in St. Louis, Missouri, the Show-Me State. As we continue to detail Washington University’s response to the COVID-19 pandemic, we look in this episode at the return of mask mandates, breakthrough infections and rising hospitalizations linked to the delta variant of the coronavirus.

Clay Dunagan, MD: Cases here are rising exponentially in some new populations. The spread among younger age groups is much higher than it was before. And in a disconcerting way, we’re now seeing the return of this virus in a very active way to underserved areas of the city. Infection rates in African Americans are four to five times what they are among other citizens in St. Louis County, as an example.

Dryden: That’s Dr. Clay Dunagan, an infectious diseases specialist at Washington University School of Medicine and BJC HealthCare’s chief clinical officer, as well as a member of the Metropolitan St. Louis Pandemic Task Force. Dunagan says the rise in cases is very concerning and already has overwhelmed hospitals in other parts of the state of Missouri. And the number of those hospitalized in St. Louis also has been rising rapidly, according to Dr. Hilary Babcock, another infectious diseases specialist at Washington University and the medical director of infection prevention and occupational infection prevention for BJC HealthCare.

Hilary M. Babcock, MD: Clearly, we didn’t reach a vaccination level that was high enough to prevent the spread of this newer variant. And this delta variant is more transmissible and can cause more significant disease. And we’ve seen the impact of that now over the last few months in southwest Missouri. And we’re now starting to see the impact of that here in our community as well.

Dryden: In addition to Babcock, we speak in this episode with Philip Payne, the School of Medicine’s chief data scientist and director of the Institute for Informatics. During the months of the pandemic, Payne and his colleagues have worked with data and computer modeling to track the progress of COVID-19. And Payne says the computer modeling didn’t predict this new wave.

Philip R. O. Payne, PhD: At the very beginning of the pandemic, when we started to build these models and think about, you know, “What should we expect? What does the surge in patients in front of us look like?” we always hypothesized that there were sort of three scenarios. So, one was a relatively sort of low rate of change, and we would have a virus that just sort of simmered in the community. The second was a model where we sort of had this rapid acceleration and a huge peak at the beginning of the pandemic. And the third scenario was basically a series of waves. And as much as we hoped for sort of the low simmer and we feared the rapid acceleration to that gigantic initial peak, we always guessed that the multiple waves was the more rational explanation for what would happen. And we’ve seen three of those waves so far in our models. We’ve been really accurate with those models. And now I think the challenge in front of us is to try to figure out what does it look like next? Because if you look at the models, there is a rapid upward trajectory, and there’s no clear peak. So we will have to change something — either our behavior or the uptake of vaccine or the model — in order to see a peak and a decline. And my money is not on changing the model. My money is on changing the behaviors in the vaccine uptake.

Dryden: One thing that is occurring to me these last few days is a line that’s often quoted, where Michael Corleone says in The Godfather III, “Just when I thought I was out, they pull me back in.” Dr. Babcock, I know that’s not really a question, but I’d like your thoughts.

Babcock: It does definitely feel like we’ve been pulled right back into where we were before, deja vu all over again. So I definitely sympathize with Michael Corleone on that, and maybe only that, point. Definitely, with this surge that we’re seeing now, I don’t think was something certainly that I had predicted. I have a little more optimistic outlook, but clearly we didn’t reach a vaccination level that was high enough, and this delta variant is more transmissible and can cause more significant disease, and we’ve seen the impact of that now over the last few months in southwest Missouri, and we’re now starting to see the impact of that here in our community as well. And I’m hopeful that the slope of the increase will be a little blunted here in our area as our vaccination rates are higher, but the projections of what’s going to happen in our hospitals is scary and is going to put us back very close to where we were before.

Dryden: One of the things that I’ve heard is that in this region, the delta is sort of traveling east along Highway 44, northeast. And I’m really wondering if it’s possible to track movement like that and whether or not that sort of idea is really accurate.

Payne: I think it’s a really interesting question, because, as we were talking about earlier, the behavior of this virus in some ways is predictable but in other ways has exceeded our understanding of how a virus like this would spread in a large population. One of the things that’s always been interesting to me is, as we’ve looked back historically with the data that we had, this virus was probably in our community long before we realized it, potentially all the way back into sort of December or January, before the first sort of reports of COVID-19 here in the U.S. or certainly in Missouri or in St. Louis. And we see that because we have data surrounding clusters of influenza-like illnesses, that when those patients were tested for influenza, they were not positive. But when we overlay that with where we see our earliest clusters of COVID cases, once we recognize the virus existed and started testing for it, they are directly related to one another. So there’s a real potential the virus was here for a while. Which leads to the question: Is the virus sort of marching along this pathway from the western parts of our state toward St. Louis? My guess is that the virus has been here for a while, but the behavior has been different here in the St. Louis region than it has been in other parts of the state, likely because of our higher uptake of vaccination here in St. Louis. But one of the things that we’ve done from the very beginning of the pandemic is not just model the pandemic in a static way. We haven’t just looked at, “Where are there cases today?” or, “How many cases do we have?” We’ve actually done a lot of what we call geospatial modeling, where we look at, “Where are the cases?” and “Where does the change happen in incidence?” And we can see evolution over time. And we’re doing that today with this most recent surge in cases. And you’re right, there’s sort of this sort of wave, if you would, of advancing cases moving from west to east. But that wave is not behaving in a consistent way. You could kind of think of it as sort of a wave approaching a shoreline where there’s perhaps a little bit more of a jagged, rocky shoreline as opposed to a smooth, sandy beach. And so it’s behaving differently when it hits those sort of jagged, rocky outcroppings. Only in our case, those outcroppings are vaccinated subpopulations within the region.

Dryden: Months ago, when cases were declining, people were getting vaccinated, but they were also wearing masks, social distancing. Is that part of why this line is going up so quickly? Not just because it’s a contagious virus, but because we’re not taking the same precautions that we were in February or March?

Babcock: So the short answer is yes. I mean, absolutely. We know that this virus, its transmission, can be interrupted by these behaviors, by wearing masks all the time around other people, by keeping your distance and not being in indoor spaces with lots of other people unmasked and unprotected. And we had gotten sort of into the habit of doing those things, some people more reluctantly than others, but we had gotten into the habit of taking those precautions. And, really, the case numbers to Philip’s point and to yours about, “We see it marching up the highway,” but really, if you look back at the case numbers, they’ve started rising here in our area in early June. This variant has been here since then. We have higher vaccination rates. We didn’t see the same explosion, and people were being a little more careful. But people haven’t — they were given permission, to be fair, by the CDC for vaccinated people to go out without masks. And I think that was taken as a fairly blanket permission for people just to be out and about without masks indoors and out in public spaces. And this delta variant is not giving us any grace. It does not cut us any slack. It is finding every chink in the armor. And so it was probably possible before that if you wore your mask most of the time, even if you were unvaccinated, you were probably OK. That’s not true with this virus, with this variant. If there is a little chink in the armor, it’ll find that. It grows to higher viral loads in the people that it infects, so they shed more out into the environment if they’re not masked. It binds more tightly in the respiratory tract so it causes infection more quickly and more easily in the people it does reach. So we just don’t have that opportunity anymore to be a little sloppy. So at this point, we don’t have a high enough vaccination rate to say that the vaccines by themselves can protect us and we need those other measures again. But we do know from when we did this before, when we didn’t have vaccines, that if we do take those measures and we do mask and we do distance and we do try to protect ourselves and our community, we can blunt that curve and we can bring that down. And we’re going to need to do that until more people can get vaccinated. Because even starting to vaccinate everyone who’s not vaccinated today, it’s five weeks before they’re fully protected. That’s a lot of viral spread.

Dryden: So even if unvaccinated people started lining up for shots immediately, they wouldn’t have full protection until sometime in September. And Dr. Clay Dunagan of the Metropolitan Pandemic Task Force says, in the St. Louis region, as in most places, this new wave is mainly affecting those who have not been vaccinated.

Dunagan: Almost everyone who comes into the hospital for COVID is unvaccinated. It’s not that we don’t have some breakthrough cases, but the vast majority of breakthrough cases are much milder than the cases in unvaccinated individuals. And in the hospital, the vast majority of patients are unvaccinated, particularly among ICU cases and those who are ventilated.

Dryden: But Philip Payne says even with that daunting news, it’s not too late for unvaccinated people to get vaccinated.

Payne: When I was talking earlier about the models, every time we had a wave of patients before we had a vaccine, how did we slow down that wave? How did we get to the point that there was an inflection point and we came back down that slope? It was always solid public health interventions. It was masking and social distancing and getting people to monitor for symptoms and stay home when they’re not feeling well. Today, we know that our best tool is actually a vaccine, which is a great thing. Now we have a tool that’s far more effective than all of those other measures I described. But it’s going to take us a while to vaccinate all the people who have not been vaccinated to get to a critical level. Well, the good news about that, as scary as it is, is we know that these other methods work. And I know people are exhausted by the pandemic. And I know that people are tired of being told to wear a mask or socially distance or don’t travel or are tired of being afraid of getting infected when they go to the grocery store, to school, or wherever they might go in public. But we have a tool to stop this wave and actually stop it in a way where, hopefully, we won’t have another wave, which are these vaccines, which work, are safe. We have more data to back up the safety of these vaccines than probably any vaccine we’ve ever deployed at this sort of scale before. And we know that these public health measures work. And so when you ask me a question about the models, I can tell you in each one of those models where certain measures were taken, whether they be early on, stay-at-home orders or masking sort of directions or any number of other public health directives, and every time we see a critical mass of public health interventions, we see a decline in infections. So we could blunt this wave today by doing that and simultaneously take steps so we don’t have another wave. Because I certainly hope I’m not sitting here — as much as I enjoy spending time with all of you and talking about COVID, we could do this so we don’t have another wave.

Dryden: One thing that I’ve heard is that with this new delta variant, the people getting infected are younger ,and there are these breakthrough infections. And what I’ve heard is that that’s because sometimes it’s coming from the bottom up instead of the top down, that what is happening isn’t that we, adults who are vaccinated, are getting infected and bringing it to our kids, but that our kids who are at daycare or at summer camp or something are getting infected and bringing it to mom and dad, and then mom and dad get a breakthrough infection.

Babcock: That is definitely true. And Philip can talk more about the data, but we are definitely seeing a change in our age ranges of our hospitalized patients and our critically ill patients, and many of them are younger now. And part of that is because that group is a lot less vaccinated so that they are — and that includes young adults. So 20- to 40-year-olds, not just young children. So we are seeing that change in the age distribution. And the vaccination rates in our older populations are much higher, and that’s good. So they are much more protected. But it’s true that breakthrough cases can happen even among vaccinated people if they are repetitively exposed to the virus, and especially if they have high-intensity exposures like a person in their household that is sick. And that is what we are seeing, is that people who have a family member unvaccinated at home who is now sick with COVID, that they can still infect a vaccinated person. The vaccinated person is much less likely to end up in the hospital, is very unlikely to get critically ill, but can get sick and can miss work and can have their life disrupted, could get complications. And so it’s still not something that we want to have happen. There is a lot of attention on the breakthrough cases, and I can understand why that happens. I just want to reiterate over and over that the breakthrough cases in the overall population numbers are very rare. And with a 95% effective vaccine, it’s not unexpected to have a few breakthrough cases. But the majority, the vast majority of the cases that we are seeing are in unvaccinated people. And if we can get those people also vaccinated and protected, then everyone’s risk goes down.

Payne: I think Hilary said it well. When you look at the data, the people who are getting sick today, that are being admitted to the hospital, are certainly younger. They have longer lengths of stay, which is a pretty good indicator that they’re sicker. And where we do see in our data individuals who are fully vaccinated and who have had breakthrough infections, they tend not to be critically ill, by and large. Again, the data is very clear that this is increasingly a pandemic of the unvaccinated population. And I can say, when you mention about children, right, in school, on a personal note, I have a 9-year-old daughter who is going to school and now camp over the summer in person. In my household, despite myself and my wife both being fully vaccinated, we’re still masking when we’re in public. And we’re certainly having our daughter mask, and she masks 100% of the time when she’s at school or camp. And it’s for the reason that she’s not vaccinated. And that means she’s both at risk of the virus until the vaccine is available for her, but also, that means she is a vector, right, that could bring that back home. We may all be done with COVID, but COVID is not done with us.

Dryden: Part of the problem is that delta is more contagious, but people are going to concerts. There are no restrictions on how close you can sit to one another at ballgames. But is it a good thing and a hopeful thing that city and county, at least in our region, have said now, “Put the masks back on indoors?”

Babcock: So I think it’s definitely a good thing. I mean, I think, as Philip has said as well, that we know that these public health interventions can work, and we know what’s required. This is not as comprehensive a public health package as a lockdown or as some of the other interventions that we had to do earlier but, I think, also, we’re in a different situation because at least some of our population is vaccinated. I am definitely still wearing masks in the grocery store, I’m wearing masks when I’m out in indoor public spaces. And I think, myself, at a baseball game, if I’m sitting in a row right next to other people, I would still have my mask on, even though that’s outside. So I think that people will make some of those personal decisions for themselves. But I’m glad that the city and the county have made this decision for us. All of us need to be masking when we are indoors in public spaces because we know that the risk right now with the case numbers like they are is just too high.

Dryden: How frustrating is that for people who do what you do?

Babcock: So it’s definitely frustrating. And I think that the clinicians who are really on the front lines and taking care of these patients are really frustrated. They’re tired. They’ve been going through this for a year. And we still want to provide great care and do our best by those patients, but there’s definitely a level of frustration with a preventable disease that we don’t have to be here. And so that level of frustration, layered on top of the fatigue and the burnout of the last year of trying to manage through this, is a real burden for our providers. Everyone is in the business of delivering health care and supporting health-care delivery is really exhausted and would really appreciate it if everyone would get vaccinated, wear their masks, blunt this curve like we — I feel like it’s back last a year and a half ago when we were talking about flattening the curve and what we needed to do to flatten the curve. And I didn’t think we would have to have that conversation again and again after vaccine was available, but we are. But then to Philip’s point, we can stop having to do this over and over and over if we can reach a high enough vaccination level.

Dryden: Babcock, Payne and Dunagan, like many other doctors and scientists around the country, say it’s time. And if everyone would get vaccinated, we’d be in a much better place. “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. If you’ve enjoyed what you’ve heard. Please remember to subscribe and tell your friends. Thank you for tuning in. I’m Jim Dryden. Stay safe.

Washington University School of Medicine’s 1,700 faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is a leader in medical research, teaching and patient care, consistently ranking among the top medical schools in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.