COVID-19 Update 9/23: Testing Accuracy, Transmission Methods, and More

We've got a special guest! This week, Dr. Steven Bishop was joined by Dr. David Pong to discuss the latest COVID-19 information. The pair talked about the accuracy of testing and strategies to improve testing results and the various methods of transmission for the virus. They also answered questions on masks, vaccines, colleges, and more. Watch the video below and read on for the full transcript. 

Testing Accuracy 

Dr. Pong: Testing is an interesting thing both in COVID and also more broadly. In medicine, of course, we want tests to be 100% accurate. We want to know that when we get a positive test it means that we have the thing we're looking for and when we get a negative test that means we don't.

Unfortunately, with COVID testing, like with a lot of other medical testing, it's not quite as good as we'd like it to be. Positive tests are actually very good. Most of the testing we're doing is with nasal swabs and this PCR testing or some of the rapid antigen testing that you have heard about and these are very accurate when they're positive. It's very uncommon to get a falsely-positive result. Positive is believable.

The trouble comes, of course, with negative tests. What we want with a negative is to know that we couldn't possibly be carrying COVID, couldn't give it away. Unfortunately, there are a lot of ways to get a falsely negative test. Part of it has to good with how good the test is. Even in an ideal situation when you know that the person is infected, they're symptomatic, you can still get negative tests anywhere from 10% to even 40% of the time, just based on qualities of the test itself. Sometimes based on how the specimen is handled. Sometimes just limitations on how good the test can be at detecting the part of the virus we're looking for.

The other main problem we get into is at different times the virus is in higher or lower amounts in different places. You can have someone ... Let's say that I'm positive and I infected Steve right now, tomorrow we could test him with a PCR and it would likely be negative. Over the next week or so, we'd have a higher and higher chance of finding it. Even if you continue to get sick, the test may actually go back to negative.

Negative tests are tough. They're once piece of a puzzle. We can put it in, think about all of the things we know about the risk, the person's symptoms, their situation, and we might find it useful to test a couple different ways or possibly testing several different times to try to improve our chances of believing the result we see. Testing can be kind of fraught with error. I encourage you to do that in conjunction with talking to somebody. If you're one of our members, call us, we'll talk to you about the timing and the appropriate type of tests to do and how to think about the results you get.

Dr. Bishop: Dr. Pong, one of the big questions that people have frequently is I've had a positive test result, but I feel okay. I'm not very sick and I've waited out my isolation period, but my employer or my organization, whoever it is, is asking me to get a repeat test before I come back to work. What's your thoughts or feelings on repeat testing and the value of that?

Dr. Pong: Yeah. One of the biggest concerns with the PCR testing is that the test looks for a part of the virus, most often, a part of the core of the virus. It's kind of like if you had a test that was looking at the bumper of a car and trying to count the number of cars by the number of bumpers. Some of us, when we have been infected will continue to secrete portions of the virus the way we might if we blew up a bunch of cars and have bumpers laying around that didn't reflect intact cars.

In the same way, weeks after you're sick with COVID, you could have parts of the virus that would make a test positive, but not have the whole virus that's necessary to get people sick. A positive test weeks after you've been sick and recovered will often not mean you're infectious and yet it'll be a positive result. We would discourage that sort of thing. We think it makes sense to follow the current guidance for people with intact immune systems.

Once you've become asymptomatic and without fever and it's been a couple of weeks since the time you were diagnosed, you really should be safe to be out in the world again. Those who have immunocompromised situation you might have to wait an extra week or two past that, but it's very asymptomatic, afebrile (no fever). It's been something in that two to four-week range depending on immune function. I wouldn't rely on testing to get you out. I think it'd be okay to be out in the world without testing.

Dr. Bishop: I think this is probably where I think a lot of people are seeing out in the media. Oh, there's been these people, they're reinfected, they're sick again, et cetera. I think there's been one or two cases where people have truly shown to have probably a recurrent infection, which is not unheard of in terms of viral illnesses. Not everybody creates a good immune response. My guess is that a fair number of these people who are reported as reinfected are really just getting repeat tests too soon.

Dr. Pong: Yes. 

Dr. Bishop: Yeah, interesting. Any other comments you want to make about testing or anything?

Dr. Pong: No. I'll just reinforce again I think it's complicated and so doing testing in conjunction with a good conversation before and after makes sense. Again, this starts feeling like testing in almost any clinical situation. We need to think about COVID as a clinical syndrome. It's got risk. It's got symptoms that we have. It's got things we can measure, including test results and we need to think about that ahead of and after testing to make sure we're making sense of the results we get.

Dr. Bishop: Yeah. There was a really nice article in The New Yorker that you shared with me which prompted this discussion and I'll put it in the comments for you all shortly.

What it really addressed was this key underlying principal of medical testing, which I think most people out in the world don't know about, which is that no test is definitive, any kind of test.

They all have uncertainly whether it's a molecular test like the COVID test or an antibody test or even an imaging scan where you feel like, "Oh, I can just see whatever is going on inside."

There's always an element of uncertainty involved in test results no matter what you do. I think as a medical community and as a nation that's really what we've been trying to wrestle through these last months is dealing with the uncertainty around all of this and the fact that we can never get too certainty on some of these questions is really been a difficult thing for people to accept. I think that's an important topic to bring up.

Transmission Methods

Dr. Bishop: I want to talk real quick about COVID transmission because ... How shall we put this delicately? Our medical institutions continue to disseminate conflicting information on an almost daily basis. The CDC this week both published and then unpublished concerns and guidelines around the aerosol transmission of coronavirus and that leads to lots of confusion.

As if there wasn't enough confusion already, people are now even more confused. I really want to just re-address that. Again, we're not at a level of certainty on this and I can't give you a "COVID is definitely transmitted this way, it's definitely not transmitted this way." But, the way I've been thinking about it and that we've been talking about it on these sessions and when I've talked about it with patients is in sort of a hierarchy of transmission likelihood. The most likely way to acquire the virus is via droplets, okay?

Dr. Pong: I agree.

Dr. Bishop: That's the within six feet, I'm breathing on you, I'm coughing on you, I'm sneezing on you, that sort of thing. The viral particles are carried in the droplets. That's the most likely way to acquire it.

Dr. Pong: That's familiar. That's like we see with colds or influenza, so that's the kind of thing that ... Perhaps the reason why we've seen less influenza in the Southern hemisphere because people have worked to prevent COVID. That style of transmission is very familiar. It's the stuff we've always talked about when our moms told us to wash our hands when we had a cold.

Dr. Bishop: Exactly. It's probably accounts for the vast majority of the transmission cases. Following that is sort of this concern about aerosol-based transmission or what's referred to variously as airborne transmission. Airborne transmission means the particles that are smaller they can travel further. The infectivity can perhaps be extended to many dozens of feet or even throughout a whole building or such as through a ventilation system, something along those lines. That's a really much more common transmission pattern for something like tuberculosis.

Dr. Pong: Measles. 

Dr. Bishop: Measles and a few other illnesses like that. For those, that's the predominant way they're transmitted or one of the predominant ways. I think that's likely possible with COVID, based on the data that's out there, based on my interpretation of the data.

I think Dr. Pong probably would agree with that, but I think it's the less likely. Because, I think it really comes down to this idea of time and exposure dose. We talked about this many, many moons ago on this session where the likelihood of getting infected is both related to the time of exposure, which is where this idea of being around someone for at least 15 minutes comes from and then the dose of exposure. Back in the beginning when we saw lots of health care workers getting very sick and dying they were getting very high-dose exposure for very long periods of time. That's probably what was contributing to the severity of their illness and the rapidity of their illness too.

There's been some data around that as well. There's this time issue, the dose issue. And so you're getting the biggest dose when you're within a few feet of people for long periods of time, but that dose really tapers off exponentially. I think there certainly is probably is some airborne element to it. I don't think it's the predominant method of transmission.

Again, this why it seems to be less likely to catch COVID if you're outside, if you're in a well-ventilated building, if you're in a place where the HVAC systems are using HEPA filters. Those sorts of things do seem to reduce the risk of getting the virus. I don't think that it is never transmitted by airborne means, but I think it is less likely. If you're instituting some of these things, I think it makes it even less likely in general.

Kind of following those things is sort of the lower levels of transmission likelihood. That's contact, so touching a surface. The main issue with that comes with touching the surface and then touching your face.

I actually think that's probably half the benefit of the masks is keeping you from touching your face after you've touched something else. And then following that is much less common.

The other routes of transmission that are sort of unmentionables. The fecal, oral transmission routes and things like that. You see them testing the waste water in various places. Certainly a risk there, but definitely in decreasing likelihood as you go from droplet to airborne to contact to fecal, oral, and then other routes that seemed to be even less likely. That sort of transmission in a nutshell there's going to continue to be uncertainty around this. Doc, anything you want to add?

Dr. Pong: No. I agree. I mean, one way we can see that is if you think about the number of people who get infected from each source, each person who is already infected that with COVID it appears to be somewhere in between what we would see with colds and flu and something like measles. It tends to trend more towards the cold and flu like transmission, but a bit higher and not anywhere near as high as what we see in terms of the number of people each source patient with measles, for example, would infect.

I think it's likely we are somewhere in between. Worthwhile to then take some steps when you're in situations with groups of people to try and reduce the amount of exposure to concentrated shared air. I think for relatively brief interactions the mask and the distancing and handwashing do very well.

Your Questions, Answered. 

• Would conducting two PCR tests or perhaps combining PCR with another type of test help to address the false negative problem? This may not be feasible, I know, given testing shortages.
  
  Dr. Bishop: What you're referring to is something called orthogonal testing as what it's called in the medical literature. Yes, that's particularly using two types of tests. Yes, using repeating tests over time and both using two different types of tests increases what's called the sensitivity of the testing. In other words, the likelihood of finding the result that you're looking for on the test results. Yes, it does help, but the testing shortages are a problem. What else?
  
  Dr. Pong: I think you're exactly right. It gets rid of some of the potential reasons that you'd have a false negative, both in time and in quality of the test, so agree. But, again, it speaks to the idea that testing should be done in a context. If you have someone at high risk where the exposure sounds like it was very high. A conduct who's known to be positive and symptomatic in your home. A negative test would be pretty hard to believe. I think would be well worth doing multiple layers of testing if you were going to use a test to try and define that.
• I've seen a quote in the media the US would need to conduct around six million tests daily to have a reasonably comprehensive sense of the spread of the infection. Do you know whether this is so?
  
  Dr. Pong: I don't know about the exact number. Certainly the ability to test with an inexpensive test that could be done where the result is very rapidly available and still high quality that is ideal. I don't know if the number is six million or a larger number, especially in settings like schools or businesses to be able to repetitively test over time with something where we could know today would help a lot.
  
  Dr. Bishop: Yeah. I think there's several questions embedded in your question, Andy. What you're getting at there is the population prevalence. This is really tough thing to tease out because when we've seen these percent positivities that the health departments are reporting, what that is is just the percent of people who are positive having presented for testing. It's a selected population of people.
  
  Of all the X people that have presented only X percent or Y percent are positive. The problem is you've had some people try to take that information and extrapolate it out to a population level. There were a lot of videos on YouTube and such a few months ago where people were doing that and coming up with these astronomical estimates of people who supposedly already had the virus.
  
  None of those things were accurate because they were trying to take the positivity rate from a highly selected population and expand it out to everybody.
  
  If I test 100 people who were randomly on the street, for coronavirus, we're probably not going to find but a couple who are actually positive.
  
  Whereas, if I test 100 people who have fever and a cough I'm going to find probably 10 times that number. You can't compare those two populations. They're not comparable in any way.
  
  I think that really becomes the issue. It's hard to identify and then to collect a random sampling of the population that's truly representative, because in general we don't test people for illnesses that they have no symptoms of unless it's things like cholesterol and stuff like that, which is a totally different beast. It's really almost not impossible to get a good idea of the prevalence with these acute tests.
  
  Now, in a couple years after we've hopefully gotten on the other side of this, we hopefully test their antibodies and see back a couple years ago it turns out X million of you got the virus and we can count that. That's not very helpful to us right now, but it may be helpful to epidemiologists and planners for the next pandemic. Anything else?
  
  Dr. Pong: And just staying on that same line, at some point we may be able to quantify the amount of antibody that we have, either in response to infection or vaccination and then we can speak to immunity the way we can with something like measles or hepatitis now. Right now, antibody testing is not terribly helpful for the individual person. Interesting, as you said, to the epidemiologies.
• What do you know about the personal air purifiers that are meant to be worn around the neck and if they're really helpful in reducing bacteria, mold and viruses? I bought the AirTamer A302, which is meant to be worn around the neck. They recommend the use of the conductive lanyard, which is supposed to cause pollutants to become negatively charged et cetera. My question is, is this a real thing or is it a hoax and how would I know if it's working? I'd like to return it before the refund policy expires.
  
  Dr. Bishop: I would recommend getting your money back.
  
  Dr. Pong: Yeah, that's a tough one. As you say, "How would you know if it's working?" That's a hard one. There certainly have been some work done trying to understand what kind of turnover of air would you need to have and purification of air would you need to have to try and reduce your risk. One would expect theoretically that this device would help you in some way, but boy is that a tough one to be able to know that you're getting your money's worth.
  
  Dr. Bishop: Yeah. And those air turnover studies are really done on room air exchanges. If you're wearing a air purifier around your neck, if you're out and about and I think if you're outside or in a well-ventilated space the risk is pretty small.
  
  I don't think you're getting much benefit from a personal air purifier, even if it was "working." The second is the air changes are designed around an enclosed space. I don't think it's helping you that much and I don't think that it's probably actually effective because there's not a bubble of air around your person that's static. It's not going to really effect the air quality around your whole person to enough degree unless it's really blowing, in which case you might look like one of those Victoria Secret models or something with the stuff blowing around you. I don't know, but it just doesn't probably seem like it's super helpful.
  
  Now, if you want to get a HEPA filter and use it in a room I think that makes quite a lot of sense as long as it is set probably honestly to the highest fan setting so that you're getting four or five changes of air every hour. That's really the sort of threshold there. And then standard HEPA filters will do the job.
• Have you heard any updates to the PCR testing results as a result of the neuroscience article about how the thresholds are set so high? I'm wondering if the labs have adjusted the threshold for positive results because it appeared that many of the positives were asymptomatic and not contagious.
  
  Dr. Bishop: What you're referring to there, Amy, is something that we talked about a couple weeks back, the cycle count on the PCR machines. To my knowledge, I don't think the manufacturers or anybody has adjusted that.
  
  Dr. Pong: Not that I'm aware of either.
  Dr. Bishop: Your question and your concern is valid as we discussed a couple weeks ago. It does call into question and, again, gets us back to his uncertainty principle. We just are not going to know for certain whether everything we did was right.
  
  That being said, I go back to in March and April. I think at this point we have the benefit of hindsight. We've luckily seen that the fatality rate, as bad as it is, was not as bad as we feared. I think at the time we really wanted to be extremely vigilant with picking up as many positives as we could, because we didn't really know what would happen. That's sort of the same thing we've talked about before with comparing the way we manage things with say the way Sweden managed things with not doing any sort of lockdown.
  
  Now, I have my own thoughts and opinions on now, knowing what we know, how should we approach things, but back in March and April and late February the Swedes were really playing roulette with their people.
  
  The fatality rate for this could've just as easily been 10% and then a lot of their people would've died. I think that our cautionary approach to this, as disorganized as it has been, was a good thing. I think we have to take into account new information as we get it, but I think it made more sense.
  
  I think that they will eventually adjust the cycle counts down on the positive results to give us a little bit more accurate information about who's contagious and who isn't. But, when they put the tests out they really were just trying to identify every possible case. I think that that made sense at the time and I have no regrets over that. 
• I feel like I'm hearing more people have very mild symptoms compared with the early days of COVID. Any data to back that up?
  
  Dr. Pong: Yeah. I was going to say that's tough. I think it may also reflect that more people who are being tested, 100% proportion of the people being tested are not as sick. We're testing more people who are not as sick as they were in the early days of the illness. It may be that early on we were having people who were not particularly symptomatic, but who also were not identified.
  
  Now, I think we're having far fewer people in the hospital, far fewer people dying. Our positive people are more often asymptomatic people who were exposed or minimally symptomatic people who have access to testing now that it's more available.
  Dr. Bishop: Yeah. We turned away a lot of people for testing in March and April just because we didn't have tests available at all. People that mild symptoms we told them, "Hey, you might have this, isolate, wait it out. We won't know whether you really had it because we just can't test you," and now we can test those people for the most part.
• Fortunately, we're no longer challenged by shortages of masks. Which type of mask is most effective or at least offers a great protective barrier?
  
  Dr. Pong: I guess I would answer two ways. Unfortunately, I think we still do have a bit of a shortage on the N95 style masks certainly in health care settings. They're not very evenly distributed and we could use more. I think the N95s do provide better protection, particularly in situations where we have to worry more about the aerosolized virus. In health care settings, I think that they are ideal when you're working with someone who you know is infected.
  
  I think that surgical masks and cloth masks are particularly good against droplet risk which, again, as we've said earlier, is the main way that the disease is transmitted. There what we're looking for is less about preventing the wearer of the mask from getting the virus, which I think we are using doing mostly with the N95, and we're trying to prevent the person wearing the mask from transmitting the virus from being a source. I think the cloth masks and the surgical masks are very good for that, particularly out in the world.
  
  I think I would try and use them that way. I think N95s are best used in hospital settings and I think cloth masks and surgical masks are fine out in the world. Probably cloth masks are fine for most of our day-to-day situations.
• I've seen quite a few folks on social media argue that public health would be served by asking all who are at high risk to isolate themselves while dropping pandemic restrictions for all others. What is your assessment of this view? To me, as a non-expert, it seems this would be bad for public health because it would increase infection throughout the nation.
  
  Dr. Bishop: There's not an easy answer to that question I think. I think that's essentially what the Swedes. It has more or less worked out sort of okay for them. Like I said, they didn't know it was going to work out that way when they did it. I think there's something to what you're saying. The younger the healthier, I think if they get it and they were to never be around older people I think that that actually would be okay.
  
  In the same way that we used to think about chicken pox. If you get it as a kid it's fine, but heaven forbid if grandma hadn't had chicken pox don't go around grandma while you have chicken pox. That same sort of thing, but it's hard.
  
  Dr. Pong: Yeah, it is. I think it's hard to separate the population that way. The other one that we've seen that's challenging is there seems to be risks that's hard for us to understand right now. I remember back when there would be these families of people where 12 people were in a setting where they got exposed and eight of them died and some of them were young people. Clearly something genetic going on in terms of the risk in that family.
  
  While I think one could perhaps juggle the numbers and say, "Well, that makes sense," certainly for those families who are at higher genetic risk who lost big segments of their family that wouldn't feel right. I think that if we are able to sustain something where we all take steps like the distancing the masking and find ways to work around it, it would probably be a bit safer than if we were to drop those restrictions broadly. I think that would be high risk.
  
  Dr. Bishop: Yeah. I think longterm we're going to have to find a much more balanced and nuanced approach to all of this to let people live as much as they can while also not unnecessarily killing people frankly to be blunt.
• What about those blue infrared wand devices that propose to kill germs?
  
  Dr. Bishop: I've not frankly seen any data on that. UV light devices are well used throughout hospitals and other settings, but they are medical grade. They are very expensive and you can't order them on Amazon as far as I know.
  Dr. Pong: And probably not great in a wand sort of way in the sense I think you sort of have to be able to contain the energy. Putting it in a box and having all the air go through the box or putting your phone in the UV light box I think has some advantage. Trying to use it sort of an open space, I don't think would be very effective at all.
  Dr. Bishop: It's probably not a concentrated enough light source for that. Probably like Debra's personal air filter they are probably not. Get your money back if you've already ordered.
• Many of the doctors quoted in media seem concerned that infection will increase greatly in the winter. What is the basis for this expectation? Do you share this concern? I know there are separate concerns that the flu might fill up ICU beds as it normally does, which would leave little room for COVID cases.
  
  Dr. Pong: Great questions. I mean, I do think that has been the concern going into the winter that the combination of COVID and influenza could overwhelm the system and as we talked earlier in this about flattening curves to be able to make sure that people who get very sick are able to get care from either one of those things is really still quite important.
  
  I think that there are two reasons that I think that we had concerns about COVID. One is at least with the first two, the SARS-CoV-1 now and the MERS there seem to be a six-month rebound curve where you saw people get sick in one curve. It seemed to tamp down and then it rebound six months later. I'm concerned that that may occur with SARS-CoV-2, with COVID-19, separate from time of year.
  
  The second part, I think, is all about time of year. Right now in Virginia, for example, our numbers are running somewhere below six percent of the tested people being positive. It's quite low. It's probably low because both masks, handwashing, distancing, but also it's easier to distance when the weather allows us to be outside and we're able to spread ourselves out.
  
  I think we run some risk as we get weary of wearing masks and such and we also have to go back inside as it gets cold... Again, we get back to this question about some aerosolized transmission, perhaps, and people just being closer together where the droplets and the fomites can be part of that.
  
  It's hard to quantify right now, but I have concerns about some of the kids who had gone off to college, groups of positives, and then people being sent back home. That pattern, if it continues, would also be a way we could see COVID rise again in communities as we get into the colder months.
  
  Dr. Bishop: Yeah. Just to linger on that for a minute, the college piece. I think the colleges, the ones that have decided to open, my personal thought on that is the cases that they've had they should keep-
  
  Dr. Pong: Keep them. 
  
  Dr. Bishop: ...leave them there. 
  Dr. Pong: Keep them. 
  Dr. Bishop: Don't send the kids home because that's spreading to mom and dad and grandma and Aunt Susie and everybody else. That's really what we saw happen in March and April here. We watched it live-
  Dr. Pong: Absolutely. 
  
  Dr. Bishop: ... as people brought their kids home from New York back down to Richmond and related areas. The virus spread with them into these local areas. It's not good to move people once they're diagnosed. Let them stay there, especially if they're not sick. If they're mildly ill or hardly ill at all let them be. Let them recover in the dorms, wherever they're at at college. Don't send them back to recede a whole lot of other communities. It doesn't make sense to me.
  
  Just to go back to Andy's question for a second, this will be my plug of the week for please get your flu shot. Lots of people have questions about the efficacy of the flu shot. I think that's totally fine. We know it's not a perfect vaccine, no vaccine is. That being said, even if it reduces the flu cases by 30% that is a huge, huge thing for public health. It's a huge thing for our hospitals, so please do it.
  
  It's a safe vaccine. It's easy to get. It's everywhere. You can get a gift card. They'll pay you to take it, so please go and get it from somewhere local to you. If you're not sure where, reach out to your doctor. If you're one of our members reach out to us and we will help you find a place to get a flu shot, so that's that.
  Dr. Pong: Yeah. Try and get that during October. Try not to stretch into November. This is the time to get a flu shot.
• College kids migrating across the nation to and from college. From a public health perspective, would it have been preferable for all colleges and universities to teach online so all could study at home? Financially, I know many schools are unwilling to do that. Ideally, what would've been best?
  
  Yeah. I would argue that because as we saw in some of the data out of Michigan when you compared schools that had online classes and had the kids in town when schools had in-person classes with the kids therefore, of course, in town, the rates of infection were similar. The problem is bringing the kids all back together in the college town. If it was possible, straight up from an infection control point of view, it would certainly have made sense to let the kids be home and do their classwork online.
• What are your thoughts on air travel right now and how would you gear up to travel?
  
  Dr. Bishop: What I've been telling people is it depends on your risk level. It depends on your risk tolerance and your risk level for the virus in general. Younger healthier people I tell them to do what the airlines are asking you to do. Wear the masks, wash the hands, do the distancing, all that sort of thing.
  
  Higher risk people, older folks, people with medical problems I'm telling them A, to wear an N95 when they're on the plane and B, I'm telling them if they can to choose an option or choose an airline that is continuing to reduce passenger capacity and leave some spacing involved. I know that's becoming less common as the time goes on.
  
  I'm currently aware of Delta still doing it. I've been actually pushing a lot of those people to Delta and telling them to fly Delta and wear an N95 mask. That's kind of my take.
• I'm a school teacher, special needs students. My county is sending the special needs kids back to the building on Tuesday the 29th. What is your take on their decisions?
  
  Dr. Bishop:  That's my county, Chesterfield, that I think you're probably discussing. My wife is a special needs educator in that county too and we do support the special needs kids going back. I think the way that they're doing it with the school system, with the cleaning procedures they have in place, with the PPE that they've distributed and everything and given that the groups of students really is small, I think that the students are going to get so much benefit out of going back that it is worth the risk to do it because they really are getting very substandard education right now via the virtual methods.
  
  I do think it's reasonable. I do think it is the right thing to do given the data from the health committee that they've been reviewing and from the Virginia Department of Health has all been a positive direction. I do think that makes sense.
  
  
• I would love an update on your outlook on vaccines.
  
  We now have four of them in phase three trials. The most recent add was from Johnson & Johnson and is a single shot, rather than a shot and a booster. I think that we're fortunate to have a number of vaccines that are likely to make it somewhere to be in distribution in 2021.
  
  I think we should plan that a vaccine will help us over the next few years, but I don't think that we should anticipate that we'll all get vaccinated in '21 and not have to do handwashing and masking.
  
  As we've been talking about, most things don't work at 100%. A good vaccine, 60 or 70% of the people who get the shot may develop full immunity for a period of time. It may not even be permanent.
  
  I think that while we can gain a foothold with a vaccine it's going to be a vaccine plus the work we're already doing, for a few years, if I had to guess. I mean, I'm excited that we have several to chose from. It's likely that we'll be able to get some people vaccinated next year, but I think it's going to be awhile before it becomes entrenched the way, let's say, tetanus vaccines or pneumonia vaccines have been entrenched in the population.