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 all things medical and scientific around COVID-19 with Dr. Bob Wachter, Chair of the Department of Medicine at UCSF. Dr. Wachter tweets daily updates with his view of the pandemic from UCSF in the "COVID Chronicles".
Q: You have become kind of a star on Twitter with your daily updates, your "COVID Chronicles." Before we get to questions can you give us a snapshot this morning of where you think we are here in the Bay Area in regards to the pandemic?
We have done extraordinarily well, comparatively. Obviously there have been many cases here and some tragedies but when we look at what could have happened and what has happened in places like New York I think we should feel very good and very proud of the Bay Area's response. We have a little more than 1,000 diagnosed cases of COVID here in the city of San Francisco and as of yesterday about 17 deaths, more than that if you go out to the larger Bay Area. You compare that with New York, which is closing in on 10,000 deaths - it's bigger than us but not that much.
We owe a lot to our leaders who gave us the right guidance early and we owe a lot to each other for doing the right thing and staying inside. Really, that was the only way we could dodge the bullets that we've dodged so far and so really so we've done quite well so far.
Q: And hospital bed and ICU capacity?We're fine. It's actually quite interesting at UCSF we have about 20 patients at UCSF Medical Center and a little closer to 30 at Zuckerberg San Francisco General. Those numbers are real and obviously each one represents a patient so there are real issues. But UCSF, for example, has 600 or so beds. You're talking about 20 patients and 600 beds. We've got four or five patients on breathing machines and we've got 60 or 70 ICU beds so we're nowhere near capacity.
And in fact it's time for us to start bringing back some of those patients that we've deferred. For the last month or so we've only been doing surgery if it was an absolute emergency. And now if you need your cancer surgery and we've held off on that or other kinds of urgent but not emergent surgeries, we're trying to get those patients back in. It's interesting some of those patients are reluctant to come. I think they worry about whether our hospital is safe and the answer is hospitals are among the safest places now. We have all of the protective equipment we've obviously incredibly clean. And we've been testing people at UCSF for the last few weeks and in the last two days we've not had one positive test out of 200-300 tests that we've done.
So the message to people is stay home unless you have to go out for essential services. But if you need surgery or need to see a doctor and it can't be done well with a tele-visit it is time to start thinking about re-engaging with the healthcare system
Q: They say takeout food is safe. Why is it safe to touch your mouth with COVID-19 contaminated food but not safe to touch your mouth with COVID-19 contaminated hands when it's the same route of entry? What are the safety measures we should take, for example how long to heat up the food in a pot or from the microwave?
Heat kills the virus well, that's part of the reason that cleaning your hands with hot water is a good idea. In terms of the food thing, it's interesting and almost a little hard to understand but it turns out to be that the route of entry for this virus and other viruses like it is the lining of your nose and the back of your nose. Just swallowing it doesn't seem to be something that makes the virus happening. It just goes down into your GI tract and passes through - at least that's the best evidence we have so far.
The reason we worry about touching things is actually then the possibility it will get into our nose. That happens if we scratch our nose, and that's when the virus takes hold.
That said it's certainly prudent to clean your food thoroughly. If you pick up food from a supermarket or restaurant it's perfectly reasonable to wash it or, if it has an outside layer, to peel it. But we're not particularly worried about eating contaminated food, it really is all about what gets into your nose.
Q: Can the virus live on food in the refrigerator? Broccoli, for example, is sold in open bins that many people may touch. How do you safely wash fresh produce that may not be cooked before eating, for example, an apple? What temperature of cooking kills the virus?
I don't know the temperature exactly but the virus can, we know, stay on smooth such as metal surfaces for a day or two. On rougher surfaces like paper and probably food it's in the order of hours. So food that's been in the fridge for a day or two almost surely does not have live virus on it.
I wouldn't do anything beyond the usual. I would wash my food - washing salad seems reasonable, washing broccoli seems reasonable. Again eating it does not seem to be the way you get the virus. So that entire process of going to the supermarket, bringing the food home - I take precautions when I go to the supermarket. Obviously I wear a mask now, I wear gloves or clean the handle of the supermarket cart. When I bring the bags into the house we usually will let the bags sit for a few hours and clean off the outside and then we put it into the fridge and cook it in the usual way. That part doesn't worry me.
Q: Am I the only one asking this serious question? If the science is inconclusive - ie masks can "help" but not guaranteed to stop - how is it OK for it to be a law?! I just don't get it and am I the only one asking?
This is an interesting time for regular people to see the world of science and how we deal with uncertainty. We do it all the time. When you come in with chest pain, we don't know for sure what it is and we ask a lot of questions and do a lot of tests to become as certain as we can be. In some ways that's the nature of the beast.
What we've all become used to here is dealing with probability. And so masks are certainly not perfect protection but they definitely are protective and there are good studies that look at communities that wore masks versus those that didn't in epidemics like this. It is clear that as a strategy for a community mask wearing makes a lot of sense, particularly at the stage we are at now.
It protects you a little bit from getting the virus in part because it reminds you not to touch your face. But in many ways the most important protection is it protects others if you happen to be infected. And now that we understand better than we did two months ago that you can be infected and feel fine, we have to do things that make it harder for people to spread the virus to others.
Why should it be a law or regulation? In part this is why laws and regulation exist. You might say, 'for my particular interest I don't want to do it, it doesn't help me that much'. But as a community if everybody said that, that would be very terrible and many of us would get sick and many of us would die.
So theres'a a community interest in everybody doing it. And in some ways that is one of the great political tensions in this - that everybody feels like "I have individual rights and that's the most important thing'. But in an epidemic there are sometimes social or community rights that trump your individual rights. And that is why the state and the public health officials have the right to do things like telling us to stay home.
Q: If a patient with COVID-19 is asymptomatic, the patient is still contagious and can communally spread the disease. Would the method of transmission need to be in a form of a cough and/or sneeze? Or can the transmission be caused via normal exhalation or strenuous exhalation (i.e. during exercise)?
That is a spectacular questions and the answer is, it's not particularly well known. I think what we've come to know in the past two months - think about two months ago we really thought that everybody with COVID had symptoms, that was the best evidence we had that you might have mild symptoms at the beginning but you're probably going to have symptoms. We now understand that it is possible to have the virus and be infected and to have absolutely no symptoms and in fact maybe as many as half the people that have COVID are like that.
It's also pretty clear you can be contagious at that stage. How contagious, and are you less contagious than if you have symptoms? I think that's a little bit up in the air. The assumption has been you're less contagious but that's not a done deal, not completely clear.
The methods of spreading it and how likely different acts are to spread it also are a little bit up in the air but it makes sense to believe that the most likely way that you're going to spread it is coughing or sneezing or something that aerosolizes virus that is sitting in the back of your nose and the back of your throat out into the air. It's also possible to spread it by doing any of those things onto a surface that then someone touches and then that person touches their nose, those are all possible.
Now with the different methods of spreading, it's logical - and you see these simulation of what happens when you cough vs. breathe vs. sneeze vs. sing - it's logical to believe that the spread would be greater and the virus would sort of go out for a longer distance in more violent acts like sneezing or coughing and singing or forced exhalation would be more than just regular breathing. But it's a little bit up in the air. And there have been certainly some of the outbreaks that have occurred like the choir practice outbreak, where people with the virus seemed to be asymptomatic and the folks who got it were standing near them when, for example, there was singing going on. Which make us think there are at least certain people who have the virus where if you stand to close to them while they're doing forced breathing or singing that that's not a zero risk situation.
All of that argues for: it's a good idea to be wearing masks, it's a good idea to be standing six feet away from us because we don't require that someone coughs or sneezes directly on to us. It's now clear you can get the virus from less than that.
Q: I need to have some documents notarized. My local UPS store provides this service. California requires a thumb print. Can the COVID-19 virus be spread because many people are placing their thumb on the ink pad?
I would treat any surface that I touch as being potentially infected. So before I did a thumb print on a pad that I know a bunch of other people had done, I would clean it with a wipe. And if I couldn't do that and I was touching something, I would be sure that I then cleaned my hands with soap and water or with a wipe and I would be sure to do it relatively quickly because we all think we're being careful about touching our face but we're not (laughs). It's the most human thing to do.
So when I go out and touch things, I try to keep my hands in my pocket as a way or reminding me and then before I touch anything else I wash my hands off or clean my hands with a wipe. And that's what I would do after touching anything even as simple as a touchpad.
Q: How important is the temperature of the water when washing hands? I hate wasting water while waiting for it to warm up.
Yeah we're the same way, our water takes a while to warm up in our house and it's annoying. I don't know the precise answer to that, most of the studies of why you should clean your hands for 20 seconds were done with hot or warm water. It's mostly the soap that breaks up the virus, the water washes the whole thing away. So if I was using water that was not very hot I would just go longer, go for 30 or 40 seconds so sing "Happy Birthday" three or four times rather than twice (laughs).
Q: If you have lupus are you more susceptible or less susceptible in contracting COVID-19 or does it matter? Also, if you do contract COVID-19 with lupus are you more at risk for severe complications?
People are asking a lot of lupus questions these days because of this issue of the drug hydroxychloroquine, which people take for lupus. If it's just a question of, you have lupus and therefore you have an autoimmune disease - the kind of disease where your body is reacting against yourself - we generally consider people with those diseases as if they have immune systems that are not functioning perfectly normally. So I have not seen any studies looking at the risks for people with lupus in particular. But with all of these things, when we look at the risk of having other diseases it's not so much that you're more likely to catch it, it's that you're more likely to have a bad outcome either because your immune system is not quite up to snuff or your organs are not quite at the same level they would be if you were perfectly healthy.
Lupus and the autoimmune diseases are particularly interesting. It's not obvious to me which way that would go. It might be implied in the question - part of the damage from the virus is from the virus directly attacking your cells and part of the damage is, in some patients your own immune system goes a bit haywire. How that works in lupus I'm not sure. The biggest issue for someone with lupus or things like it, rheumatoid arthritis, inflammatory bowel disease, maybe even cancer is probably not the disease itself unless you're quite sick. But if you're then on medicines that suppress the immune system, that would most likely put you at higher risk of a worse outcome from the virus than if you didn't have it. So if I had any chronic disease - and I would just put lupus in the list of chronic diseases - what we know is for the same age if you have a chronic disease the changes of getting sicker with COVID are higher than if you didn't have that disease. So I would be particularly careful.
Q: My normal temperature is in the 96.7 range - has been all of my adult life. Does that mean that my trigger temperature for a COVID alert is lower than 100?
Well the first point is that the use of temperature as a COVID alert is problematic. We do it and we're probably going to see more places doing it. It wouldn't be shocking to me in a couple months as we're going into a restaurant or going onto a plane that they're checking our temperature. The problem with that as I've already said is about half the people with COVID - maybe a little bit less but close to half - have no symptoms. At least half have no fever at the beginning. So it's not a perfect test to make us worry that someone has COVID. If you do have a temperature then obviously the worry goes up.
And I think that's probably right, our temperatures really relate to our baseline. So if you have a baseline of 98, a temperature might be 100. If your baseline really is 96.5 your baseline might be 99. That of course is the problem with public programs to check your temperature if they don't know what your baseline is.
The alternative point - and its important for people because this is so confusing - at UCSF now we're doing COVID testing on some patients with no symptoms of COVID. We're now starting next week every patient in the hospital getting checked. This week we're checking every patient who's gonna go for surgery.
But until a couple days ago the only people we did testing on were for people with symptoms; people with fevers or cough or shortness of breath. I can tell you that every single one of those people thought they had COVID. I mean it's just natural in today's world if you have a fever and you're coughing you think you have COVID.
Our positive test rate is running at about 4%. Meaning that 19 out of 20 people, essentially, who think they have COVID do not. So everybody with a fever thinks they have it. Chances are very good that you don't - I can't tell you you absolutely don't. Why is that? And in places like New York that number is more like 20-30% of people who are checked have it. It has to do with the prevalence in the community, because we have such little virus in our community, we've dodged this so amazingly well. And there still are a lot of viruses around. If COVID didn't exist there would be a lot of people running around with fevers and coughs this time of year.
So most people who have had those symptoms in the Bay Area will turn out not to have COVID and many of them have gone home and isolated themselves and not been tested and they of course all think they had COVID. They may think they therefore have antibodies for COVID and the chances are that they don't.
Q: There's been talk about false positive or negative tests - so if you do take that test and it comes back negative is it possible that you actually do have COVID but the test was wrong?
We always look to, 'what is the gold standard when you say it's a false negative, how do we know that you actually had it?' Those are studies that have looked at repeated testing and things like that. It does look like there is a false negative rate in probably the order of 20-30%.
So all of those people who have been tested for COVID and are negative - the vast majority in the Bay Area don't have it and never had it and we'll find out in more detail as antibody tests come out. But for those people - you still had a virus almost certainly, you still are potentially infectious and we can't say with a 100% guarantee that you don't have it. So the prudent thing to do is to isolate yourself for a while because the questioner is right, there is a possibility of a false negative.
Q: I have asthma and wonder if I were to contract COVID-19, is it okay to continue taking my Albuterol, or would that draw the virus down deeper into my lungs?
It's not been demonstrated that the Albuterol or anything like that will draw the virus down deeper into ones lungs. I think the greater risk would be if your asthma were out of control and the virus went into your lungs that you would get sicker, because that is the main way that it harms people. I would keep taking all of your asthma medications. I'd want my lungs to be as healthy as they can be.
Q: I'm a stage four lung cancer patient who wants to know how I can tell the difference between my lung breathing problems and COVID?
I guess it all depends on, are you off your baseline? When we tell people one of the symptoms is being short of breath and you're always short of breath, that's tricky. So the real question is, are you worse than you normally are?
Q: Should ACE inhibitors and receptor blocker anti-hypertensive medications be changed in the face of this?Not clear. The questioner obviously knows that the virus seems to latch onto a receptor in the lungs that is similar to the receptor that those drugs go after in treating your blood pressure. At this point there's research going on into whether we should stop those medicines or we should start people on those medicines with COVID - that just tells you the level of uncertainty.
I think at this point I would stay on my medicine in part because we know that high blood pressure appears to be a risk factor for bad outcomes with COVID and so it makes sense to have your blood pressure well controlled. If those are the medicines that are working for you I think at this point there's not enough clarity about whether they might be harmful for it to be wise to stop them.
