As we continue to navigate these unprecedented times, KCBS Radio is getting the answers to your questions about the coronavirus pandemic. Every morning at 9:20 a.m. Monday-Friday we're doing an "Ask An Expert" segment with a focus on a different aspect of this situation each day.
Today we're looking at the transmission of the virus and the risks involved with different daily activities with Columbia University virologist Dr. Angela Rasmussen.
I wanted to get a "top down" view from you before we get going with the listener questions. Obviously here in California, things are not going very well. Do you see this as the worst it's going to get? Could it get worse? How do you read it?Well, I think we've certainly already seen it get worse in some of the states that have an uptick in cases. In Texas and Florida and Arizona we have this major problem with now hospitals being at capacity in many places and we have started to also unfortunately see the number of deaths ticking upward as well. I think that California has done one thing, right, and that is that yesterday Governor Newsom closed down indoor dining, closed down a lot of these indoor environments that we know are higher risks for transmission. And being willing to pull back on reopening in that way is going to be really essential for controlling these new surges and cases when they happen.People look at the rest of the world and they see people in France and Germany going on vacation. They even see the British - and they've had certainly their battles with this - apparently living a little more free life than many Americans seem to be able to do. What's what's going on here? How do we account for all that?Well, there's a real difference in how a lot of those countries have responded compared to the way that the U.S. has responded, and that is that they have been very slow to reopen without testing and tracing and isolation and quarantine measures in place. Here - and we're seeing this right now in those states that I mentioned before and also in California, where reopening has occurred - we haven't had community transmission at a low enough level. The way to do this safely is to test a lot of people, test them routinely even if they don't appear sick, identify new cases, trace the people that they've been in contact with and quarantine those people until you can confirm they're not infected. And that's how you break those chains of community transmission. We have not been able to successfully do that and in some states they've reopened, essentially, too quickly when there was still too much transmission occurring in the community. And when that happens, transmission is going to go back up.So in Europe, in many of those countries where people are going on vacation, they're still taking some measures, you know, physical distancing, they are actively testing people, their testing capacity is good and so they are able to keep it under control. Whereas here we have a lot of transmission that we just aren't even recognizing because we're not testing enough people and because we've really rushed into these reopening activities,Well, let's dive into these questions that have come in via email at askus@kcbsradio.com. First one says: Drs. Fauci and Gottlieb agree that we're only detecting about 10% of all infections because of serious under testing issues. Given that, instead of saying the U.S. had 70,000 new cases yesterday, for example, why don't we simply say the U.S. had about 700,000 new cases? Wouldn't that be much closer to the truth and would it help people understand how serious the pandemic really is?This is probably a question for me, but he's asking you.So I think that the reason why we report 70,000 new cases instead of 700,000 new cases, is those are the number of tests that have come back and confirmed those cases. This 10% estimate, while I agree with it, it's not really a very exact estimate necessarily, and there's going to be different levels of transmission in different communities with existing different numbers of cases. So we don't say that just because we can't say for sure that that is the actual number. We don't know that it's exactly 10 times more than what we're being able to test for reporting. I think, though, it is really important to emphasize that we are under testing. And so there is much more community transmission than we can document. And people really need to understand that this is a danger and a threat in everybody's community.My friend wants to bring her elderly parents from Mexico city home to the U.S. She lives in a city with low transmission. The pandemic is really bad in Mexico City, her parents are cooped up in a small apartment with no opportunity to exercise. Is putting them on a plane too risky? What if they wear a mask and face shields and fly first class so it's less crowded? Is this a fool's errand? Could it be done safely? Should they wait a few weeks to see if the lockdown lessens the caseload there and then fly?Well, that's a tough question. And that's really one that every family, every person kind of going through this is going to have to deal with their own comfort level for risk. So there's no way to get on a plane and fly completely safely, but as that listener pointed out, you can take certain precautions. So certainly wearing a mask for the entire flight, face shield, those can help. Sitting in an area of the plane that is less crowded can also help to potentially reduce risk, but we don't really know that much about the risk of air travel. And a lot of it has to do with people's behavior. It is thought that people with influenza anyways, can infect people up to two or three rows in front or behind them. People could also potentially get infected by wandering around the aisles of a plane. So there's no way to really completely eliminate that risk. So it really just depends on those people's health status, their comfort with getting to the airport, getting on a plane, taking that trip and potentially being willing to quarantine for several weeks after they arrive here in the United States. I think that that's how you can make it as safe as possible, but even then, you know, some people are not going to be comfortable taking that level of risk.I hear daily that kids going back to school won't be a problem because children are less susceptible to the virus. Where does that evidence come from? Because I hear it every day.So that evidence, I think, comes from some conflicting studies. So it's pretty clear that children can be infected with the virus. We know that children do get infected, we know that they have detectable viral loads and a recent study showed that they can actually produce infectious virus in their upper respiratory tract, suggesting that they can shed it and transmit it. However, there have been some epidemiological studies that have suggested that children are less likely to transmit the virus to other people, but again, the evidence is conflicting. There are other studies that suggest that children can effectively transmit the virus to other people. So this is really a we-still-don't-know-that-much-about-it kind of topic.I think that it's really dangerous to assume that kids going back to school won't be a problem at all. Both because we are not sure that kids are less susceptible to the virus or less capable of transmitting it. And we also have a lot of transmission in our communities, and there are more people at schools besides just children. There's faculty and staff, those children are going home to their households and they are part of the community. Schools are not an isolated bubble. Children and their families exist in the community where transmission is already occurring. So right now, with the levels of community transmission that we have, schools aren't necessarily any safer than any other place. And so that's why we really need to think very carefully about how we open schools and how we can do it safely, but we certainly should not assume that children are less capable of getting infected or that they are less likely to transmit the virus to others.Our bike club's been in conversation as to how far we should distance from each other when riding in group pace lines. This type of riding is done for aerodynamic reasons, et cetera. Currently we're telling the riders that each person should maintain six feet distance from the rider ahead, which pretty much defeats the effectiveness of riding closely. What do you recommend in terms of distance between riders in these situations? The average speed's about 18 miles an hour on flat terrain and we do wear masks at rest stops, but not while riding.Well, I think that's a really tricky question because not that much is known about it and there are several competing factors that would come into this. So we know that outside, especially if there are strong air currents, there is a reduced risk of transmission or at least exposure, we think. However, if you're exercising and you're in close proximity to other people outside, you're breathing heavily and you're not wearing a mask, you will be producing more of those respiratory droplets that people can be exposed to. And whatever size they are, whether they're larger respiratory droplets like those generated from coughing, or smaller respiratory droplets, if you have a bunch of people all producing them in an aerodynamic bubble, it may actually cause an increased risk of exposure. So I would advise, probably, not doing that. I realize that there are reasons to ride that closely. At the very least I would consider wearing masks while riding, but I would say that maybe you make some sacrifices in terms of your aerodynamic efficiency, for the sake of reducing risk for all the people in your bike club.I can say as a cyclist, you get a better workout when you're not drafting somebody. So there's that. Okay, next question. I've seen a fair number of people wearing their mask, but not over their noses. Some doctors say that's the same as not wearing a mask, others say you don't create droplets from your nose. Who should we believe?Well, I don't think it's completely true that you don't create droplets from your nose. You may create more droplets from your mouth because your mouth is larger and we speak with our mouth, we vocalize, so you can force out more air, thus pushing out more droplets. But you can certainly still produce respiratory droplets from your nose. So while nobody's really quantified the protectiveness or the number of droplets that would be reduced if you were just wearing your mask over your mouth only, any source of respiratory droplets should be covered by a mask, including your nose, just because that is the purpose of the mask. It's for source control to prevent you from expelling as many of these droplets as possible into the environment. So I don't know that it's the same thing as not wearing a mask at all, but it certainly is a reduced level of protection and source control if you're not covering your nose with your mask.I'd like to know that if I am asymptomatic, does that mean I will only be asymptomatic for two weeks or am I a constant carrier?That's a tough question because asymptomatic is notoriously difficult to prove and asymptomatic largely relies on people reporting their own symptoms. And sometimes people will think, "oh, you know, I'm a little tired today, but that's not really a symptom." So it's very hard to say if somebody is truly asymptomatic, because often even patients who have been reported to be asymptomatic have actually shown radiologic evidence of disease in their lungs. So it's hard to say, you know, when people are truly asymptomatic or have mild disease what the long term effects of this are. But it does look like many of the people who have milder symptoms do have less virus. And they do clear the virus infection. So they're not going to be like a "Typhoid Mary," for example, who is feeling perfectly fit and healthy and still capable of transmitting the virus to many people. There's less of a likelihood that these people are going to be shedding as much virus, but we also don't know that much about it, partly because asymptomatic infections are very difficult to detect. If people aren't getting tested and we don't have enough testing, you're going to be missing a lot of those cases. So the bottom line is you're probably not going to become a constant persistent carrier. But it's really an open question how likely it is that you will transmit virus to somebody else when you are asymptomatic.This next question says, do asymptomatic people create antibodies, and do they test positive for those later?So that's an excellent question and it's one that we are getting a little bit more information on. It does appear that antibody titers have a relationship. They correlate with the severity of disease. So if you do have milder or asymptomatic disease you're less likely to have high titers of antibodies. And it seems that in some people, at least, those antibodies can go away or become undetectable several months after being infected. That said, we still don't really know about protective immunity and how that works with this virus to say that that's a bad thing just yet. It may be that you have reduced protective immunity because these antibodies go away, but there are other immune mechanisms of protection. So we just really need to continue doing research and find out a lot more about how long term immunity, especially, works for this virus before we can make any firm conclusions on what that antibody data means.Since the vaccines in development are based on different theoretical concepts and use different methods for preventing you from getting the coronavirus, had there been any considerations of one individual getting more than one vaccine? Would that be safe, to get two different kinds of vaccine?Well, it really depends on the types of vaccines and the types of antibodies that they elicit. And we don't know much about that either, unfortunately. Usually people do not get different types of vaccines for the diseases that we have multiple types of vaccines for, you usually get one or the other. And I think in this case that's probably going to be what people are going to have to do, also because of manufacturing issues. So as soon as we get a vaccine that is effective, they're going to try to manufacture as much of it as possible, obviously, to get the vaccine to as many people as possible. If there's more than one vaccine that's available, people will probably have access to one or the other, but not necessarily access to both. And that's really a good thing because we want as many people as possible to be vaccinated. That's how we're going to actually beat this pandemic.I've been diagnosed with chronic fatigue syndrome. Would that be considered an underlying condition, should I contract the coronavirus, and put me at higher risk? I'm also 72 years old.I would say that it probably does count as a preexisting risk factor. There's a lot that we still don't understand about ME/CFS - or chronic fatigue syndrome - in general. But it does appear to have a relationship with certain viral infections. So it is entirely possible that there could be some adverse effects from getting COVID if you have chronic fatigue syndrome. And certainly in this caller's case, their age is also a known risk factor.I have heard the virus is mutating. If so, does this make a vaccine unlikely?No. So currently the virus is mutating because that's what viruses do, especially RNA viruses like coronaviruses. Mutation is a normal part of viral replication, and sometimes some of those mutations stick around. There's been a lot of confusion as to whether this means the virus is becoming a new strain, especially because the one mutation that has really been in the news, which is in the spike protein that's on the surface of the virus particle is thought to be the important antigen,, we call it that a vaccine will be directed to. So that's what the antibodies that are potentially effective at clearing the virus are targeting. So yes, it is possible that a mutation in spike could lead to a virus that is distinct, or is recognized as a distinct entity by your immune system. However, the mutation that has been characterized is not thought to be in a part of the spike protein. That's really important for antibodies to do what we call neutralize the virus or render it non-infectious. So right now it doesn't look like this particular mutation is actually making this virus into an immunologically distinct strain. So right now we have no reason to believe that this will have any impact on the vaccines that are currently in development, which is good news.Now we have a few versions of this next one: does anyone know how much virus it takes to infect someone? How much virus an infected person gives off? How long would it take to become infected? I guess this is the time and distance and viral load question.Yeah. So this is a really important question that we don't know the answer to. So in terms of what we would call the minimum infectious dose, like the minimum amount of virus you have to be exposed to, to get infected, we don't know that for people right now. People are determining that for animal models, but those are not necessarily the same as it's going to be for people. And there's also a lot of really open questions about, are some people shedding more virus than others? How much does behavior come into play here? And I would say that it's probably a combination of all of those things.If you're engaging in higher risk behavior - not physically distancing, not wearing a mask, et cetera - and you are producing more infectious virus from your nose, that could increase the risk of transmission to others who are around you. But we don't really have a lot of data to put numbers to that. So these are all very important questions that are undergoing research as we speak. But we don't really know the answer to that yet.Is it safe to schedule my kid's physical exam or should I wait until this is all over?I think that probably physical exams are fine. I have myself been to my doctor for my annual physical exam and they're being very careful about making sure that people are distanced in the waiting room. They wouldn't let me in unless I was wearing a mask. They talked to you quite a bit about whether you've had any kind of symptoms and will give you a COVID test if you have. I think that it's really important to remind people that they shouldn't neglect their normal medical care, whether that be just your annual physical, it's really important that people get their annual checkup. For older people getting mammograms and colonoscopies and preventative screening such as that is still really important. People should make sure that they are still keeping up with their normal healthcare routine including getting pediatric annual physical exams.Do you think the time has come to restrict people's travel to within five or seven miles of their home as many other countries did and got the pandemic under control?I don't know. I think that that would be one measure that we could take to try to limit transmission, especially effectively importing cases or exporting cases into other communities that are further distant from your own. I also think though, that would be incredibly difficult to enforce in a country as large and as diverse and as mobile as the United States. Certainly some states have talked about having a travel ban for people from other states. But that's still in many cases - policing and setting up roadblocks and a lot of different roads - I'm just not sure that we actually have the manpower to do that and to enforce that. So I think in some places, perhaps it's a measure that could be undertaken, but I'm sort of doubtful about what that would look like in practice.I've heard a lot of reports about testing problems, also about really fast tests using saliva. Why aren't those tests getting wider usage?So the saliva tests and some of these at home tests that are rapid have just not gotten emergency use authorization from the FDA, and that's a required step in order for these tests to be available to the public. So I think that the FDA is taking a very close look at those things. Obviously I think everybody can understand the importance of having more testing that's more easily accessible, and that would be potentially less invasive than the current tests, which use these nasopharyngeal swabs that people compare to sticking a Q-tip into your brain. I think that having these tests would be fantastic, but before the FDA can approve them, they need to make sure that they actually work and that they're not going to give people false or misleading results. Because the last thing you want is to take a test that tells you that you're negative when you're actually positive. And then perhaps you don't quarantine or isolate yourself, you go out and engage in behavior with other people that might be riskier and transmit the virus, potentially, to other people. So that's why the FDA has to review these tests very carefully to make sure that they actually work before rolling them out to a larger group of people.