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 are taking more questions about the virus and medicine science with Dr. Bob Wachter, the chair of the UCSF Department of Medicine.
Since we last spoke, we've reached this point where the Bay Area's kind of reopening bit by bit, county by county. Are you able, from where you sit, to note any effects, medically or in terms of public health of these reopening moves?
So far the Bay Area is doing great, fingers crossed - it's not all luck, though, it's doing the right thing. But the number of hospitalizations in San Francisco has stayed low and is continuing to fall - about 55 patients in all of the hospitals in San Francisco. The number of deaths that we've had in San Francisco over the entire time of the pandemic is still in the low 40's, which is just remarkable. But all you have to do is look a few hundred miles south and you see that none of us are immune to an outbreak. The California numbers are going up and it's largely on the strength of increased virus, increased cases and some new deaths in Southern California - largely Los Angeles, Kings and Imperial County. So we have to remain remain vigilant, but at least here so far we're not seeing a signs of an uptick in cases
You touched on something that does have people scratching their heads a bit. We've got Santa Clara County, San Mateo County, San Francisco County, each with roughly the same number of confirmed cases, right? But the deaths are wildly disparate. San Francisco: 43 deaths. San Mateo, twice that many and Santa Clara County, three times as many as San Francisco. What do we make of that?
Yeah, hard to know. I think Santa Clara, I would probably attribute to the fact that they got hit earlier than the rest of us and we we didn't really understand some of the things about the virus and some of the treatment options have changed. But there's probably some randomness is to it as well. A lot of it depends on who is getting sick and what their general health is and what their age is. I haven't looked at it carefully enough to know, but if the case numbers are the same but in one group of people that are getting sick are younger or have fewer other illnesses than you would expect the death rates would be somewhat different.
Okay, let's get to some questions now. These have come in via our email inbox at askus@kcbsradio.com. First question: I see reports about the reproduction number, which I understand is a way of measuring the spread of an epidemic. I'm not sure I totally understand this or where we stand when it comes to this measurement, can you explain?
Sure, it's a great question. So one of the things that determines how bad a virus is going to be is the average reproductive number, which basically is for every person that has an infection, how many other people are they likely to infect?
And that number for flu is about 1.3, I think. So if you have the flu, on average you're gonna infect another person, maybe 1.5 more people. For COVID, that number is closer to 2.5, so it's about twice as infectious as as the flu. One of things we've learned just in the last couple of months is this phenomenon of super spreaders that you've all probably heard about, which is that in that average of 2.5, there are some people that infect one or zero and then others are capable of infecting 50 or 100. We don't exactly know why that is, but that has become clear. And it's one of the rationales to not have big groups together, cause if you have a conference of 100 people or a baseball stadium of 40,000 and you have one of the super spreaders there - and they don't have signs on their forehead - all of a sudden you can get a lot of cases, and then each of those people go out and spread it three more.
So that's where we start from. What all of the maneuvers that we've been doing: sheltering, mask wearing, distancing are designed to do is decrease that effective number. Meaning that left on its own devices, your case will spread it to 2.5 others but in a world where people are keeping apart from each other and everyone is wearing masks, that number goes down below one very quickly, meaning the average person that has COVID will spread it to fewer than one other person. And you can do the math, over time the virus begins to die out. So that's that what our goal is.
In California, we have gotten that number down below one, which is where you want it. It's now about 0.9. You'd like it to be even lower than that. But the balance now, as we begin to open up, is if we're not careful, if people aren't wearing masks, if people are congregating too much, that number could go back above one. And that's when you start seeing more numbers of cases, more hospitalizations and ultimately, more death.
Let me ask you real quickly about the super spreader concept. We think these are people who are spewing more virus than anybody else? Or they're in more contact with more people or they lean in closer when they talk? What do we think?
You know Stan, we've talked enough times that I'm hoping this will not lower your opinion of me, but I will tell you that we have no idea (laughs).
(laughs) Honesty is the best policy.
We really have no idea. It's gotta be some combination of the way they speak and maybe the distance they have to others. And maybe there's something about their virus. And maybe there's something about the anatomy of their mouth and their nose. But from the studies that have been done so far there's none that I've seen that has convincingly given me an explanation for what it is that makes that person a super spreader and this other person not. And it's not just that they're a super loud talker and they're six inches from your face.
You know, we've seen it in choir groups, we've seen it in churches, we've seen it in medical conferences, so different kinds of people. But one of the phenomenons - you can be a super spreader but if you're staying far apart from people or you're wearing a mask, you're not gonna super spread. So it is one of the main rationales for why we don't want big groups to get together because if you happen to get a super spreader they can spread it to a lot of people very quickly, but we really don't understand what it is about them that's different.
For people who have COVID, why do their symptoms become worse at night?
I don't have a great answer to that other than the fact that everybody's symptoms for almost everything get worse at night. Our fevers all go up - even those of us who don't have a temperature, your temperature actually does go up over over the course of the day and gets higher at night. At night you're sitting there quieter and you can concentrate on your symptoms more. So it probably is just a manifestation of the normal human variation. And symptoms of the flu get worse at night, symptoms of most things that related to fever and your immune system sort of kicking in all seem to get worse at night. I don't think it's anything specific about COVID there.
We're gonna get into some some medicine here so I'm out of my league here, I may ask this wrong, but maybe you can walk me through. If someone has a documented condition of specific antibody deficiency - low IgA to high IgM - which makes one susceptible to some bacterial infections i.e. causing sinusitis, are we more or less susceptible to COVID-19 virus? Doesn't low IgA to high IgM impact virus susceptibility?
I don't know the answer to that. Let me make sort of general point there that there are people that have immune deficiencies. Their immune system is not working as well, sometimes genetically, sometimes because they're on medicines that do that. You know, one would assume that the inability to mount an immune response would lead to worse infections, because the infection really is a balance between the strength of the virus and the strength of your immune system tackling the virus. The only hooker there is that some of the damage from COVID actually is from your immune system. And this is not that uncommon in medicine that the virus sort of sets things off, it's the match, but then what happens? Your body begins attacking the virus, and sometimes the attack is over-exuberant and can begin to be an attack on your own body.
That's probably what's happening to these poor kids that are having this odd syndrome we talked about a couple of weeks ago, a few weeks after they had the infection. So on average I would imagine that someone has local antibodies in general - it's a little bit too complicated. to get into which antibody - but has low antibodies in general might be more susceptible to a bad viral infection. But there may even be an argument that they might be protected somewhat from the over-response of the immune system. I don't think I've seen any studies that say in real life how that would play out.
Having not left the house since mid-March, it takes a lot of willpower to obey a public health order in order to flatten the curve and quash this pandemic. However, many want to know how those who test positive and have been ordered to isolate for 10 to 14 days are monitored for compliance. Do you have any insight?
Well it's mostly the honor system these days. There are countries out there where people have to report in with their cell phone where they are, they have they randomly get a note - I think this happens in Korea, Taiwan, it might be - where they will randomly get a text message saying, "take a picture of where you are now and send it in". We haven't resorted to that in the States yet and I'm guessing we probably won't do that.
If you're told to stay away from people for 14 days, it's for good reason and you should do that. In general, what we know is that around day 10 or 11 after you first had symptoms, you are no longer capable of infecting someone else from your virus. And even these cases of people that are persistently testing positive, what we now know is after about 10 or 12 days, that's dead virus. It's no longer live virus.
Now, people continue can continue to feel sick for a while. That's probably no longer the virus doing its thing, that's probably your immune system wreaking some havoc. I guess I'd say also for the person who hasn't left their house in three months, if you're a highly vulnerable person, meaning you're at higher risk of a bad outcome because you're over, let's say 75 or you have a lot of preexisting diseases, you may be doing the right thing. But keeping six feet away and wearing a mask, I think you can feel pretty safe at least getting out of the house and walking around. I do worry about people being almost too shut in. My parents in Florida, who are 90 and 84, spend most of their time in the house, but I at least encouraged them to get around and take walks and get some fresh air.
My dad's 90 and he's been doing the same thing, and I think you know his mental attitude is pretty darn good. It always has been.
Next question, a recent article claims COVID-19 is actually a vascular infection, which is why doctors see strokes, heart problems and organ damage. What's the science around this?
The science is real, it is one of the many superpowers of COVID in that we thought it was just a respiratory infection. In the beginning it gets in the back of your nose and throat and then, in bad cases, goes down to your lungs and can cause a severe pneumonia. We now know that it causes the clotting system to get a little bit out of control and can attack blood vessels as well.
I read that article as well. I thought it was a little bit over-exuberant that it's all a vascular problem. If you look at the majority of causes of COVID it really does look like a regular respiratory infection that can sometimes have a really bad course and attack the lungs. There certainly are cases, though, where an important manifestation of the disease is what it's doing to blood vessels. And once it starts hitting blood vessels, that's when you start seeing potentially damage to the heart, damage to the brain, damage to the kidneys. And some of that is probably from the actual attack on blood vessels and other parts of it might be because it could screw up the clotting system. So the blood vessels can cause problems either because they're getting gummed up or because the vessels themselves are inflamed and it looks like COVID can do a little bit of both. And that is a problem. It's not the dominant problem, it's not the reason that people are getting sick and dying from COVID by and large.
If I go swimming in a lake when it's allowed, can I catch the virus from another swimmers? Is it transmissible through water?
It seems to be awfully safe. Water is kind of like being outside, in that is very hard to get infected outside because the volume of air is so great. And we know now that it's not one viral particle that you get that's going to get you sick, it's got to be thousands. And so the volume of a lake is so large, the idea that someone who has COVID in the lake is gonna infect the entire lake and someone else getting to get infected - I don't think there's been a proven case like that, and it would be something that I would not worry about it all.
Can COVID be spread by blood or urine or sexual contact?
As far as we know, the answer is no. The recommendation now is not to screen blood donors for COVID. This is a purely respiratory infection, meaning the only way it gets in and that it causes disease is that it gets into your mouth, nose or eyes, and then burrows into what's called the respiratory epithelium, the lining of the inside of the back of your throat or the back of your nose. And from there it's how it causes infection.
The amount of SARS-CoV-2, the virus itself, in the blood is minimal. There's not been a reported case of someone getting COVID from a blood transfusion or a donated organ. And so, as far as we can tell, that is not the route by which it spreads. It pretty clearly spreads through the respiratory route only.
Do two eight-year-old friends need to wear masks when on their scooters or bicycles in a play date? Is it a problem if they get closer than six feet with or without masks, which is going to happen. We hate to keep yelling at them to stay apart.
Oh, yeah, and I hate to keep yelling my dogs for barking (laughs). But the answer is, the probability of them getting infected if they're outside and not hugging each other but staying at least a few feet apart is extremely low. We know that kids tend to have much milder disease than adults and at least so far, the predominant evidence is that kids don't spread it a lot to adults, which is surprising and good news.
There was one report that's just come out of an Israeli school of a high level of spread that's making a lot of us a little bit nervous because all of the evidence up to that was the kids are are pretty safe. That said, you should try and all you can do is try. You know, in general, if people are not going to be able to keep six feet apart, they should wear masks. And I think framing it to the kids to try to do one or the other: if you're gonna get closer than six feet apart you need to wear a mask.
And there was a big analysis of all the studies today: six feet is a good number to make it really safe. Three feet is better than one foot. So you do the best you can and anything you can do to keep them a few feet apart. And if they're gonna be much closer than that for a prolonged period of time, try to get them to wear masks. But I used to have small kids and I know how tough this is.
As shelter in place orders loosen my extended family's going back to life as normal to some degree. Going out to eat, visiting friends. I have a six week old infant. What's the best advice to protect her? Should people be allowed to see her, who are out and about? We're currently not letting people older or even visit unless they're still sheltering in place or in quarantine. My family is not happy about it, and thinks we're over reacting.
I don't think you're overreacting. If I had a small child I would be very careful. As I said, the kids seem not to get bad disease, which is the good news. On the other hand, there have been several hundred cases of this odd multi-system inflammatory disease in children who didn't have symptoms of COVID when when they had it, but weeks to months later developed this pretty bad syndrome and some kids have died of it. So I would be very careful. The hugging thing is really hard with a little kid, but if I couldn't confirm that someone was free of virus or had been living a life to make it highly probable that they're free of virus, meaning they've been staying inside and doing all the right stuff, I would be reluctant to have someone come very close to my child.
My teenage son's dental appointment is scheduled for this week. Safe to see the dentist now?
It really depends on what the dentists are doing. In some ways it's riskier for the dentist than it is for your kid. They've always been very, very good at infection control. I remember the early days of HIV where they had just come to completely transform their offices in order to to be safe, and all dentists did that. So I'm confident that the dentist will do everything that he or she can to keep everybody safe.
Personally, I would not be going in for my routine cleaning. If I needed something done from a dentist because I was in pain or something more urgent I would. I'm over 60 so I'm in a higher risk group. But that's an area where you now have two people six inches away from each other's faces. So I'd still be a little bit on the careful side there, but we're gonna have to open up a some point. Certainly the dentist needs to be wearing a mask and I think it would be legitimate to ask the dentist what he or she is doing to keep the patient safe.
I'm living on the fourth floor and a person who lives down from me smokes a lot on the balcony and I see the smoke through my window. If the person who smokes has COVID, can he or she transmit it while smoking?
Well they can transfer it while smoking, but is the smoke itself carrying the virus? I guess the answer is, if you have COVID, you're putting out a little bit of virus every time you breathe. The virus is not being carried on the smoke. Smoke is kind of a marker, that there is a something coming out of a person's amount that you can smell, and then it's legitimate to wonder, if I could smell it, if that were virus coming out, could I be getting it? The answer is that the number of viral particles you need to get infected is high enough. So if you are more than six - and it sounds like in this case you're probably 20 or 30 feet away - and all you are is smelling smoke, the chances that you are going to get it from that are essentially zero. And if this is in San Francisco, the chances that person has COVID is incredibly low, assuming they're asymptomatic. Certainly about less than 1 in 300 right now. So very, very low chance of being infected. If I was sitting there and truly breathing in smoke after smoke, for me I would move away, I wouldn't want to keep on breathing mostly for the smoke rather than the virus.
Glucose steroids: do you think it might be a bad idea to prescribe anti-allergy medicine containing glucose steroids? Some over the counter? Do you think it might be counter indicated since these drugs and other forms might affect the immune response?
A little complex, let me see if I can do it 30 seconds. So glucocorticoids or steroids - the most common ones you might have heard of a prednisone or hydrocortisone - do suppress the immune system somewhat. The ones that you use for nasal allergies like nose puffs or a puffer into your lungs have very local effects, don't suppress the overall immune system very much. I think if I needed those for allergies, it's fine to take those. It doesn't lower your immune system through your entire body enough to be meaningful.
Separate question about whether those drugs are valuable in treating COVID, and there have been some early studies that show for patients that are very sick in the hospital there may be some benefit to being on those drugs, and that gets up the issue we talked about before that some of the damage is not from the virus itself. It's from the over reaction of your immune system. And that's what those drugs are designed to dampen down.
