Answering Your Medical And Scientific Questions About Covid

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 medicine and recent studies suggesting the exposure to the virus in California may be much higher than previously thought with Dr. David Agus, CBS News medical contributor and professor of medicine and engineering at USC.

Let me start with this controversy that's erupted around these serological studies out of Stanford and out of USC, which looked at about 3,000 people in Santa Clara County, a slightly larger group in Los Angeles County and came to the conclusion that tens of thousands of people in each county have been exposed to the virus but don't show up in the case count. What's your take?

So this was a study that looked at who has been exposed - not who has immunity - but who has been exposed. And what it's saying is that our testing now is identifying 1/50th - there are 50 times more cases than we're identifying. The data in New York City just came out and showed that up to 13.5% of the city had been infected. The number was 4% in Los Angeles. So what that means is, lots of people who are asymptomatic. And when you're asymptomatic and you can spread the virus, it's kind of a recipe for disaster. Because not meaning so, you can go out, you can go to work, you can talk to friends and that can lead to the virus continuing to spread and that's what we're worried about.

Given that, is wearing a mask made out of a bandana enough?

One more point I wanted to make there is that the good of that data is that the death rate is remarkably low. So if you counter in the new denominators, the new number, the bottom of the fraction - our death rate is much much lower than had been forecast.

And yes, a mask is very very helpful. When you talk, when you cough, when you breathe, droplets come out and this virus hitches a ride on these droplets. Wearing a mask blocks most of the droplets and so you will dramatically decrease the ability of you to spread to others by wearing the mask. Remember, you're wearing the mask to protect others not just yourself. And then there's the notion where, when you hurt your knee in a basketball game and wear an ace bandage, it doesn't make your knee heal faster but it reminds you "don't stress that knee". So when everyone has a mask on, they behave differently and we can actually do real social distancing and we won't forget - this is a new behavior for all of us and that reminder of the mask as well as blocking the droplets helps us remember.

Let me circle back to the denominator question because that has been so challenging through this. Do you feel we're beginning, with studies like this, to get a grasp on that, which will tell just how big this thing really is?

That's a great question. We need data and this is the first real data out of the United States. There's been a lot of data coming out of China and South Korea and other countries, but we haven't been generating much of our own data. Obviously we have fallen behind dramatically on testing. And with testing we can have an understanding of where the virus is, how its spreading, who's more susceptible, who's more likely to get sick. These still remain open and unanswered questions.

Let's get to these questions that have come mostly from our listeners at

We've been told, if sick, to not go to hospital unless and until you have experienced difficulty breathing. There are reports coming out now  - and you probably saw this from from Dr. Richard Levitan who wrote in the New York Times - that by the time you're having trouble breathing it's possible you're really in trouble with much lower blood oxygen levels than would be expected. So is it better to have a pulse oximeter at home? (If you can find one.)

There's no downside to having a pulse oximeter. It's a little device, it costs about $75 and goes on the tip of your finger and through a particular wavelength of light, tells you how much oxygen is in your blood. And you get a percentage where 100% is perfect and something below about 92% means that you're low on oxygen. And so you can put it on the end of your finger and know where you stand. 

And what you're referring to is that Levitan said that some people, not knowing so, were low on oxygen and they didn't feel that they were short of breath even though they were. One way to actually look at that, even as good as a pulse oximeter, is just counting the number of breaths a minute. It's amazing, but you can't do it to yourself for you actually change the amount you're breathing. But if someone looks at you when you're breathing and your number is above 20, it probably means you are short of breath even though you may not know it. If your number is about 16, which is normal, you're probably not. When you go jogging your number of breaths per minute goes up because you need more oxygen - this is the same. 

I have a medical concern that’s not Covid-19 related. I emailed my doctor several weeks ago describing the condition and he told me to send a photo. I did that, but the photo was not detailed enough for him to diagnose the problem. He told me to contact him if it gets any worse. How can I get an in-person appointment for something that could be serious? I'm just a layperson, I don't know.

You're hitting an issue. First of all, telemedicine is not very good. We all say, "well we're moving to telemedicine". It's not very good. I practice it, and I will tell you I'm not having great experiences in a lot of patients. 

Number two is, doctors are only seeing patients with acute illnesses. So what we're seeing in hospitals is actually decreasing heart attacks, decreasing cancer and other things because people are staying home. And when you stay home and don't get medical treatment, bad things can happen. Obviously this should change over the next several weeks in mid-May as California, presumably, will open. And you have to look at yourself: if you feel that something is going on, you need to fight back with your doctor and say "you know, I really think something is going on here" and push to go in. I, like every doctor am seeing patients with conditions that need to be managed rather than seeing what we call "elective appointments". So if you feel that there's something wrong, you should go in.

Do I have to wear mask in my own front and backyard, doing some work or taking the garbage out to the street?

It depends how public your front and backyard are. The role of the mask is that anybody within kinda 6-15 feet of you, you are blocking droplets that can affect them. So if you live in a part of town where there aren't many people, the answer is no. If you live in a part of town near the city where people are walking by all the time I would certainly wear  a mask. It's also a sign to everybody walking around you that you respect them.

How important is one’s temperature to helping determine whether you have, have been exposed to or might have had the Covid-19 virus?

It's a variable. About 20-25% of people who present with Covid-19 have a fever so it certainly is an important thing to look at and measure. But many people don't have a fever when they present. And obviously if you take Tylenol or ibuprofen, the fever can go away. So it's a piece of the puzzle but it's not the only piece.

Can you get the virus through a cut or open wound?

We certainly don't think that's the dominant means of transmission. Almost all cases have been spread by droplets. And so while it's important to wash your hands and clean surfaces, almost all cases are spread by droplets. And so that's where we have to focus our effort, that's where we have to focus our energy and if you do have a cut, put a band-aid on it. Just be safe.

I am single and live alone, I don't have anyone to bring it home to, so why can't I go fishing and camping by myself and only go to the gas station like hundreds of people are doing and not interact with anyone. FYI I am worried about the B.S. not the virus.

We put measures in that are somewhat extreme for the one simple purpose that is, we all have to change our behavior to stop the spread. What we're seeing now is that in February, we thought that there were a few cases in the country. There were actually lots of cases and it was silently spreading. And what we're worried about with that silent spreading is, just one person went to a meat packing plant in North Dakota and 900 people are infected with the virus now. And so we have to be really cautious. 

Obviously doing things on your own, when you're sure you're going to be alone certainly makes sense. The hard part is, it's always hard to know when someone's going to walk by or someone's going to be close and we worry about that. This virus has a relatively low death rate but it selects and it discriminates, and it discriminates people with medical conditions, blood pressure, diabetes, anyone over the age of 65 is who it targets. And in those people it can be very very deadly.

A person who recently tested positive informed me I am a potential exposed person. I work in agriculture and we had a meeting while maintaining social distancing and wearing masks. How concerned should I be?

There's always some concern but it certainly sounds like you did the right thing and so the concern is significantly lower. But we all have to pay attention. And given that we're all in this stay at home mode now, there's no chance that you're going to spread to someone else unless you're with people in your house. And if you are you probably should be a little bit socially isolated from them and just pay attention over the next two weeks. 

This is something that's going to be the new normal. We're going to get notices that say "hey you just talked to somebody who turned out to have it, you need to pay attention or you need to stay home for two weeks". This is going to happen and we have to accept that. We all have to work together on this one and then we will be victorious against this virus. If we don't work together and let our guard down, bad things will continue to happen.

Is any consideration being given to prophylactic combination of anti-viral and anti-malarial medication being prescribed? Especially for people who need to go out of state or out of country.

That's a great question. We call that post-exposure prophylaxis. If you have the flu, I give your spouse a drug and she most likely won't get the flu. Take with HIV, if you're exposed to HIV I can give you a drug afterwards and dramatically decrease your incidence of the virus. And so the hope is these drugs - the anti-malarials, the anti-virals - will work in that setting. The clinical trials are ongoing and obviously encouraging people to participate in those clinical trials and then doctors are using it in certain patients that are higher risk and have known exposures. And so we'll get the results hopefully soon. I pray that one of the trials is positive and that one of these agents at least, or more, actually have benefits. Because we all need that. Our shoulders will go down when we have drugs that we know work.

For people who have coronavirus but are asymptomatic, does their immune system kill the virus after 14 days? In other words, how long are they able to spread the virus?  

It's a great question and the real answer is we don't really know. This is a unique virus in that the day you present with symptoms is your highest amount of virus. Normally with the flu, you can present, have a little bit of virus and then your immune system comes in and gets rid of the virus. Here you present with a high level. So if you are going to be symptomatic, the days before symptomatology you can spread the virus and you're infectious. If you're asymptomatic there still is a period where you can spread the virus. 

And what we're learning now is that people can test positive weeks after clinical symptoms go away or after they've had negative tests. And we don't know what that means. Does it mean that the negative tests were false negatives? Does it mean that the virus changed and there's a new virus? Does it mean that immunity wasn't enough to keep it? We just don't know yet. And so the humbling part about this virus is that it's all new. We don't know its behavior and as scientists, we're really just learning as we go. And that's what's frustrating. So little is known and also so little data is collected for us to learn more. So every time we collect data it's a kind of gift to learn about the biology of the virus.

From what I have heard and read, it will take a year to a year and a half before a vaccine is developed. I have also read that viruses mutate and by the time vaccines are developed, they are no longer of much help. Could you address the risk of developing a coronavirus vaccine that would be useless by the time we'll be able to use it?

It's a great question. We've tried to make vaccines to coronavirus for many years. Remember, a third of common colds are coronavirus and we haven't been able to make a vaccine. 

When the SARS and MERS epidemic happened, they made vaccines and actually some of the vaccines made people sicker. They would be to a part of the antibody that wasn't required for getting into the cell - it would cover up or coat the virus. And what would happen is the virus would be shielded from the immune system. So we need to use all of the science and all of the data we have in these vaccines. 

And there are a few of the efforts that I'm very encouraged by, in that they've learned from the past and they're choosing regions of the virus that are integral to the virus, that we hope and pray and think the virus can't live without. So the virus does change. In these areas that are necessary, it won't change. You know in over 5 million years of evolution, our human genome changed 1%. This virus can change 1% in a day.

I understand that many elective surgeries are on hold, but where I live in Napa County there are very few hospital beds occupied by covid patients, and generally speaking patients with knee replacement surgery go home after a day. Under this scenario, shouldn't hospitals change their policies in this regard?

What you're referring to is that there are various differences in incidences county to county in the state of California. So in some places hospital beds are near full, in other places they're empty because they've eliminated all elective surgeries.

I think what's going to happen now with our governor and our individual mayors is, they're going to start to make decisions. They're going to be different for different parts of the state. So in a part of the state where there isn't a significant utilization of hospital beds and we're not as worried because there's low numbers of cases, maybe it makes sense earlier to allow the elective surgeries which obviously people need. We call them elective, but they're cancer surgeries or orthopedic surgeries that are certainly necessary yet when you do them is elective. So it's going to be individual decisions by the mayor and governor together. I'm pretty confident in the government we have here in California. I think our mayors and our governor have acted very very well to protect us and I think they're data drive.

I don't have the virus. Is there ways to improve my lung health to help combat it if I do get it?  

That's a great question and the answer is we don't know actually what baseline lung health actually means. That's a funny statement but the data from NYC for example showed that having asthma wasn't a risk factor for getting sick with the virus. 

And so certainly, while we're all stuck inside the more we walk and move the better we're going to do. We can't give up on exercise. It is critical. The better shape we are going in, if we do get the virus, my hope and prayers are the better shape we're going to come out of it. So the more things you can do to just move and occasionally doing aerobics - that is using your body to get short of breath, push yourself a little bit - certainly will have benefits in the long run, I think.

A number of my friends keep saying "It's just like the flu. What's the big deal?" What should I say to them that has some evidence I can point to about how Covid-19 is different? I need some science in my answer please.

Great question. I'm excited by this one. So the simple answer is the following: with the flu we have a vaccine. With the flu we have drugs that we know work. With the flu we can predict when it's going to happen and its numbers so that the medical infrastructure is ready. With Covid-19 we have none of those. 

And what's interesting about Covid-19 is how easy it is to spread when you're asymptomatic. So what that means is much much larger numbers of people with the disease. And then the part that really gets us all, is a small fraction of people get really sick. And we can't predict who that fraction is going to be. So we're all worried that we're going to be in that fraction. We're all worried that our parents or neighbors are going to be in that fraction and we all have to act in that regard. 

But when you have a virus that is very contagious, much more contagious than the flu, when you have a virus that starts to attack and be symptomatic in people that you can't predict - we're pretty good at predicting who is going to get sick from the flu or have manifestations, we're not with this virus. And so we have very little science that we understand. 

It's not the virus that's causing the problem when you get sick, it's actually your own immune response to the virus. And that's making the lungs leaky, fluid goes in, it's difficult to get oxygen across and people are getting short of breath and many times have to go on ventilators to assist getting oxygen into the blood. And so this is a new process. We know so little about this virus, about its biology, its physiology and its natural history that we're all worried. We're worried that in South Korea, 141 people turned positive after they had two successive negative tests. Again, what does that mean for the biology of the virus? What does that mean for our immunity? 

We as a country, in the United States don't yet have a test for immunity. So we don't even have a test yet to know who is immune to the virus and so once the technology catches up, once we're good at testing upfront who has the virus, once we have immunity tests and we can deploy them to the country, once we have a drug that we know works and the medical infrastructure is ready, our shoulders come down. And then we're waiting for that vaccine to come. But those first steps are doable, we have the technology, we have the people we just have to implement them. And then our shoulders will come down.