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 brought back Dr. Bob Wachter, the chair of the UCSF Department of Medicine to talk about testing the options, the reliability, and the meaning and the value of tests.
Facebook just put up a map this morning, a sort of crowdsourced attempt with Carnegie Mellon University. They’ve created opt-in surveys, asking people to self-report coronavirus symptoms: loss of smell, cough, fever. These are not confirmed cases, but might be. Is this helpful to know what a broader and perhaps not quite so scientifically sound basis how widespread things are?
It’ll be one piece of data among many as we try to look for the state of outbreaks.
As we move to another stage, having an early warning signal that something seems to be happening in Pittsburgh may be useful.
If people start reporting symptoms, or if people start doing Google searches for fever, or cough, or loss of smell, it can give you a sense that something might be happening in a region.
It’s relatively unreliable, meaning that…up until very recently, almost everybody we had tested for the virus (with symptoms), all of them believe they have it, and about less than 4% have been positive.
A study came out on Friday, it’s an unpublished data gathering aspect for antibody testing of a group of people recruited through Facebook. Is there value in that information, so far, in regards to the number of people showing antibodies to COVID-19?
The study got a lot of press, and it just shows how hungry people are for information. It gets very confusing (these two different types of testing).
What we’re seeing now is a toggling from the PCR testing (polymerase chain reaction) for the virus—which tests to see if you have the active virus in your nose—to antibody testing.
That study out of Stanford was one in which they’re now testing for the antibody, which means you had the infection and now 1-2 weeks out from the infection and you’ve built the antibodies.
As we go forward, it’ll be particularly useful to figure out whether people are actually immune to getting infected again. We don’t know for sure yet if having antibodies equals immunity, but we certainly hope that’s true.
That particular study, as you said, has not been published yet, has not been peer reviewed, and there are a lot of concerns about the methodology: How accurate was the test? Is recruiting from Faceboo? Does it get you a random sameple of people, or people who have answered that had to go out in the middle of a stay home order, one who are mostly likely to have had sympotms and be worries anbout it?
What the study showed was that the percentage of people that have antibodies is 50 times higher than the number of cases. If that’s true, then there are more people who’ve had the infection that we believe. I think we’ll find that’s not true.
I think the best numbers that we’re seeing from other kinds of data sources are that the number of reported cases is probably 10-20% of the true number of cases, meaning the people who had a case and got tested, and it was positive.
Certainly the number of people with COVID-19 is higher than the number of people that have had confirmed cases. But if it were 50 times higher, then that would imply that everybody in New York City would be infected, and that can’t be true because all sorts of new people are coming in with diagnoses everyday. So if everybody was infected, it would mean the entire city had antibodies and there’d be no new infections. That’s not possible.
So I don’t buy the results, I think they’re going to turn out to not be correct. And the best number seem to be maybe 5-to-1, maybe 10-to-1, meaning if you have a community where there have been 1,000 confirmed cases, maybe there actually are 10,000 people that have antibodies and had the infection.
We know that as of this morning here in the Bay Area there’s something like 6,3000 confirmed cases. Is anybody following these people to see what their antibody situation looks like a week, a month, two months downstream?
I don’t know whether it’s being done systematically in the Bay Area, but you’re going to see more and more studies of people who have a positive viral test, recovered and then checked for antibodies.
There have been studies like that done in China. That’s where we get the data that says most everybody seems to develop antibodies. What we don’t know with 100% certainty yet is whether those antibodies are fully protective against being infected again, and that’ll be crucial to figure out.
It’s a fair assumption based on what we know now that if you did have COVID-19 and recovered from it, as most people will, you will develop them. The average time that takes is about 11 days.
Should people be asking for an antibody test and a test for the virus? Is this a good idea for the future?
They’re two different things.
If the question is: How many people had the virus over the last six months (in a certain community) and may be immune to it? At this point, then the antibody test is the only one that’s useful.
If you have symptoms and your question is ‘Do I have the virus?’, then you’re looking at the nasal swab viral test.
You hear everybody talking about ‘Are we ready for the next phase?’ and one of the questions that always comes up is ‘Is what we need more testing?’.
The testing they’re mostly talking about is the test for the virus as opposed to the test for the antibody. And the reason for that is the next phase, which would be some loosening of shelter restrictions.
Let’s say we in the Bay Area get to a point where the number of new cases is small and getting close to zero and falling. We’re not there yet but we’re moving in the right direction.
The minute anybody has symptoms, they need to be able to easily get tested and we need to figure out if they have COVID-19. If they do, we need to go and find all the people they’ve been in close contact with for the prior several days and we need to test them with a nasal swab for an active infection.
That’s why the antibody test is not useful when you’re sick. The antibody test really tells us the overall state of a community over the past several months.
It gets us into herd immunity, where if a given region got to the point where 70% of the people had the infection and developed antibodies, then at least theoretically the virus will begin to die out.
But even in New York, the best estimates are now that maybe 10% of the people there have had COVID-19, and in the Bay Area certainly no higher than 1%.
My understanding is that herd immunity occurs when so many people have become infected and therefore immune that the virus can no longer find a host. We can then consider opening things up again. How can we achieve a herd immunity when we’re being told to shelter in place so we don’t become infected?
What we’re trying to do is prevent people from getting infected. If the virus was really benign and the chances of dying from it were like the flu—one in 1,000 versus one in 100 with coronavirus—then the idea of everybody kind of getting infected and becoming immune might be attractive.
The problem is, it’s deadly and can be deadly.
The best way to handle this is trying our very, very best not to get infected, to stay away from each other, and to keep the level of infection very low in the community while we wait until effective treatments or a vaccine to come out and distributed across the country.
The reason that trying to get to 70% (herd immunity) is unattractive is because 70% of the U.S. would be 200 million people. Even if you get a 1% mortality rate—and there are some regions it’s running higher than that—that’s two million people dying.
We’ve, so far, in the U.S. had 40,000 deaths. So you’re talking about an unbelievably tragic toll, and that’s not the best case scenario.
Is there a profile for asymptomatic people? Is it just young people, or can anyone be asymptomatic? And for people who are, do we know if they clear the virus within 14 days and thus are no longer contagious?
In the beginning, we thought you were going to have symptoms, and it turns out that the best study seemed to show that about 40% of people have the virus never having any symptoms at all and will clear the virus. So if that happens to you, it’s lucky, it’s terrific.
It makes it difficult, though, to find you and to then find your context. That’s made some of the issues of case finding and contact tracing particularly difficult. I don’t believe there have been any studies that demonstrate a difference in the probability of asymptomatic infection.
Older people are more likely to get sick, have to go to the hospital, more likely to have bad outcomes and more likely to die. So I’m guessing that the probability is asymptomatic infection is higher in people who are a lower risk, meaning younger people. But some of the asymptomatic infections happen in older people, as well.
We first became aware of the asymptomatic infections in the studies on cruise ships. The virus is on handrails, which just turns out to be a very nice incubator for everybody on the ship getting infected. The average age was about 60 and we learned that about 40% of the people in those environment had been asymptomatic. Those are that number that are in other environments where there’s been very rapid spread, for example, the choir practice and business conference.
So those are area where it was mostly, I believe, missed aged to older people.
I think everybody can have asymptomatic infection, but the risk of a bad outcome go up if you’re sick, have a preexisting disease or if you’re older.
I heard that COVID-19 cases excess clotting. Is that primarily what is causing trouble breathing for patients and has anticoagulant medicine helped?
More recent studies have demonstrated that one of the things that goes haywire in people who are very sick with COVID-19—particularly with bad lung diseases in the ICU—is their clotting system is not working correctly, and they’re more likely to have clots, or what we call thrombosis.
It does not yet say that trying to give them blood thinner is a good thing to do. There are studies that are ongoing of that question. It will be interesting to see whether that’s an important part of why they get so sick.
My guess is that it will turn out not to have a major role in treatment. It’s been tried in certain places and we’ll have to wait for the results.
I would not routinely use anticoagulants because they can harm you, so it’s always a risk-benefit equation when we put people on blood thinners because they become more likely to bleed. But certainly the information we have makes it a worthy thing for us to study as we study other potential treatments.
Is swimming pool water safe from this virus? I’m a family lap swimmer losing her mind for not being able to swim.
I don’t know the answer to that with 100% certainty, but I would bet that the answer is yes.
Although it can stay on a smooth metal surface for a couple of days and on paper for several hours, the glory of the virus is it goes away very (easily).
The idea that it would stay in large enough quantities in a pool and withstand the chlorine seems inconceivable to me.
I have not seen a study of that, but I wouldn’t worry about swimming.
Will gargling with mouthwash or hydrogen peroxide help suppress the spread of COVID-19?
It has not been proven to do so.
The virus mostly come in through your nose. It latches on what’s called the epithelium, the lining of the inside of your nose. And then it can descend down the back of your throat into your lungs. It’s the lungs that gets people in trouble.
The the theory would be that if there’s something that you’re doing with haggling that might catch a virus that’s in your nose before it transits down into your lungs.
The one that’s bandied about the most is zinc, which has pretty powerful antiviral activity. It’s not wacky to do that, particularly if you’ve had an infection in your nose or had been exposed.
It’s reasonable to gargle. Not completely ridiculous to take zinc pills, but both have not been proven to be beneficial.
What is the policy at UCSF for ER treatment? Can a loved one go in with a patient if the problem is not COVID-19 related? What’s the chance of exposure if you did go in?
We’re struggling a lot with this because it’s very difficult for patients who are in the hospital, sick, and sometimes getting surgery to not be able to have loved ones visit them.
At this point, we’re not allowing it. And it’s not even our choice, it’s by order of the city Health Department. I believe all of the Health Departments int he Bay Area have the same orders.
We believe the hospital is safe, we’re testing all of our new hospitalized patients, everybody int he hospital is wearing masks. And so we’re looking forward to a day where we can being loosing the restrictions. But right now it’s out of our hands.
There’s a wonderful project going on, being led by our residents and medical students using donated iPads to allow patients to communicate with their loved ones. We’re doing the best we can with that. But obviously we’re all looking forward to the day we can liberalize the guest policy.
Since everybody’s wearing a mask, any sense of how to keep your glasses from fogging up?
If someone could figure that out, I’d love to hear it. I’m having the same exact problem.
