KCBS Radio went to the experts to answer your most pressing questions about the coronavirus, how it spreads, and how you can best protect yourself from becoming infected.
Anchor Stan Bunger posed listeners' questions to Dr. Art Reingold, Professor of Epidemiology at UC Berkeley Public Health, and Dr. Lisa Winston, a Professor of Medicine at UCSF and is the Hospital Epidemiologist at Zuckerberg San Francisco General Hospital and Trauma Center.
Q: How often do we need to disinfect surfaces like doorknobs if we’re sheltering in place? We only get grocery delivery and walk the neighborhood.
AR: Typically what we would want would be to disinfect only if there’s been recent exposure of that surface to potential contamination. There’s no need to repeatedly decontaminate a surface unless there’s been an opportunity for it to become contaminated.
Q: So, if you’ve just gone out for a walk, no problem, but if someone from the grocery service touched the door you should decontaminate it?
AR: If others have touched the surfaces that you’re concerned about then yes, that would certainly be a reasonable reason to re-apply whatever decontaminating solution that you’re using.
Q: If we can’t find sanitizing wipes or any other pre-made disinfectant, how do we make our own?
LW: There certainly have been some difficulties finding the usual cleaning supplies. There are a variety of things that people can use in the household to clean and what’s been particularly recommended if there is somebody living in the house who does have COVID-19 is to use dilute bleach. Otherwise, people can make their own sanitizer or cleaning solution from vinegar.
The CDC website has a lot of information on the different cleaners and whether they will kill the coronavirus. Just keep in mind that most of the cleaning advice that you see is in areas where there are either many people who are touching surfaces, like public areas, or when somebody in the household has coronavirus and you’re trying to prevent transmission to somebody else in the household.
Q: How much bleach do you need to put into a gallon of water to get the right concentration?
LW: It’s five tablespoons to a gallon in warm water, or a third of a cup.
Q: If a person gets COVID-19 and survives, are they then immune to the virus or can they get it again?
AR: The quick answer is, the information on this is really not understood yet.
Based on what we know about some viruses, including the coronaviruses, is that immunity might be present but if it is it may only be present for a few years, it might not be lifelong the way it is with measles. The honest answer is we don't know, but there’s reason to believe that you'd probably be immune for at least a couple of years.
LW: There’s no reason to believe that this coronavirus would be different from other viruses in terms of immunity. Most viruses do give you some period of time where you have immunity and you’re exposed to the same virus.
Q: I’m a senior and have been hearing some things about not taking ibuprofen. I take it daily for fibromyalgia pain and some arthritis, what would your advice be?
LW: This came out in a few different ways and I think caused a lot of concern, but a number of medical organizations have weighed in on this and don’t believe that there is any problem with taking ibuprofen or other drugs of the same class. Of course, we should only take medications that we need because medications can have side effects, but there is not a particular reason to avoid ibuprofen.
Q: Two cars are driving one after another both are windows down, the first car driver has COVID-19 and the other doesn’t. Because you often smell smoke from passing cars, should this be a matter of concern?
AR: The quick answer is no. The reality is that the vast majority of the transmission of this virus occurs by droplets and often in a household setting. I think the scenario being described, to me, would not pose a risk.
Q: What’s the recommended way of disinfecting fresh produce? Can this even be done and is it safe to buy right now?
LW: As Dr. Reingold said, the way that we think this virus is really transmitted is by droplets generally being within six feet of someone. When the cases have been studied, most of these are from household transmission.
There really isn’t any evidence to suggest that people are getting COVID-19 through food, and when you do have food related transmission you tend to see particular patterns of disease spread, and we’re not seeing it with this. I would actually say that in terms of fresh produce, we would be more concerned about the usual things that can contaminate our fresh produce like salmonella.
We should always do a good job of thoroughly washing our produce before we eat it, but I don’t think it’s necessary to discontinue getting fresh produce and I don’t think there’s any data to suggest that getting it from one place rather than another place would be safer.
Q: Can the COVID-19 virus be spread via a sick person’s sweat contaminating a surface? Also, do the paper toilet seat covers in restrooms do any good?
AR: We don’t not believe this virus is spread via sweat or a toilet seat, you really need to get this virus into a mucus membrane like your eye or your nose, so getting it on your skin we don’t think would result in infection. I also know of no evidence that the virus is present in sweat.
Q: I’ve heard the virus is more prevalent in people with Type A blood, is this true and if so, why?
LW: There’s a study that came out of China that looked at a number of their cases in which they had blood typing available and compared it with the blood types in the general population. What they found was that people with blood type A were slightly over-represented in the group that did have COVID-19.
Even though this result was statistically significant, the difference in the percentages was quite small. There were certainly people who had other blood types who had COVID-19. The difference seems to be rather small and that study has yet to be peer-reviewed, meaning it hasn’t been looked at by experts. As far as I know, that’s the only study describing it. I haven’t seen that in other populations. There are other organisms like norovirus where your ability to get the disease is affected by your blood type. So it’s an interesting observation, but it’s probably a small effect.
Q: I’ve read the virus might live up to 24 hours on porous surfaces such as cardboard, is there any concern about virus transmission on the mail or your newspaper?
AR: Those are laboratory studies that have been done recently, I believe in the Netherlands, to study whether the virus is viable or still detectable on various surfaces. We don’t really have any evidence that we’re having transmission to be people via paper and plastic, but these studies do suggest that there can be survival on plastic or certain types of metal, like steel, for a number of hours and somewhat more briefly on paper and cardboard. We really don’t know the significance of that with regard to human infections at the moment.
Q: I’m a senior and cancer patient, most of the COVID-19 deaths come from people like me. Obviously, underlying health conditions can come of varying seriousness, but what is the percentage of seniors with underlying health conditions that contract the disease but survive it?
LW: This is a good question and I know it’s a source of anxiety for many people. We don’t yet really have these data broken down by particular health conditions. We do have them broken down by age, and we do know that starting at around age 50, you start to get small increases in the people that have more severe disease.
As we go through each decade to those who are over 80, the chances of dying from the disease go up. But at every age group, even though the risk goes up, many people will still have more mild or moderate disease, which is the rule of thumb and much more likely for those that are younger. I would say that it is important to be concerned if you have underlying health conditions or if you are older, so it’s very appropriate to try to keep yourself from getting this virus and following the public health recommendations. We can’t really say for a particular type of cancer exactly what the risk is compared with the general population that doesn’t have it
Q: I’m concerned about the transmission of the virus through mosquitos, given that summer is right around the corner, is this a worry?
AR: We have no evidence whatsoever that any coronavirus is transmitted via mosquitos or other insects.
Q: Are all the COVID-10 tests manufactured the same in regards to sensitivity and specificity?
LW: Whenever we’re doing testing we always think about sensitivity and specificity. Sensitivity is the ability of the test to detect the disease when it is present and specificity is if you get a positive result that you do in fact have the disease. The tests we’re using are PCR-based tests that are very specific. If you find the virus present, it suggests that it truly is there. The sensitivity can depend on a variety of things, it can depend on exactly how the sample is collected and how early in the disease you are testing someone.
AR: Like many things, we’re still learning a lot about the characteristics of the PCR test, at the same time that blood tests are being developed. The more important point to make about the PCR test is that we don’t know with 100% certainty whether a positive PCR test means that you are still infected infectious to others, and secondly you could be truly negative today and two days later be truly positive because the virus wasn’t there at one point and then was there two days later. So, interpreting these tests can be quite difficult and we still have a lot to learn.
Q: I see a lot of people wearing masks, should I be wearing one and if so what kind?
LW: Health care systems are thinking a lot about this and we know that many people in the community are thinking about this, and when you turn on the TV or walk down the street you see people doing a variety of things. Health care workers are using very specific types of masks or respirators for protection when they are caring for patients who are known, or are suspected to have, disease. In terms of the general public, the two things that are more important than wearing a mask are keeping your distance from other people — this is a virus that doesn’t spread far, it only spreads within six feet — and then keeping your hands clean.
There’s not a specific public health recommendation to wear a mask, but if you do choose to wear a mask, you can wear whatever is comfortable and available to you. I think people should note that the main thing that you’ll be doing if you're wearing a regular mask in public is that you will be preventing your cough from infecting other people. Your mask may not necessarily be filtering the air to protect you.
Q: It seems like we would have to stay isolated until everyone has somehow been inoculated. That could take a year or more if it takes that long to get a vaccination. If that’s not the case, why not?
AR: We’re certainly not going to have a safe and effective vaccine for at least another 12-18 months, that’s not coming to our rescue. In theory, if we all became naturally infected an immune, or the vast majority of us did, then we would have herd immunity and in essence the outbreak would end in the absence of a vaccine. I think in the meantime what we’re trying to do is minimize the risk of exposure to people while we don’t have population-level immunity, particularly the frail elderly, so that they don’t become ill while we wait for better therapeutics and for a vaccine.
Q: How does the virus get tracked into a home, by shoes when returning from a communal safe? Should we remove our shoes or disinfect the soles when we get home?
LW: Many people are thinking about this, and in fact health care workers are thinking about this too when they come home from a healthcare or hospital setting. This has been looked at in at least a few small studies and it doesn’t look like clothes and shoes are something that is contributing very much as to how this virus is being spread. They can occasionally be contaminated, but that is really in a health care environment taking care of a patient who has COVID-19.
I’m not aware of any studies that say going for a walk contaminates your shoes, but if it’s something that worries you, many people take their shoes off outside before they enter their home. There’s nothing wrong with doing that, it’s pretty easy if it’ll make you feel better. And if it makes you feel better to wipe them down with a damp paper towel, it would be perfectly fine to do that. I would not go to great lengths to do something that’s difficult or inconvenient because this is not going to significantly affect your risk of getting coronavirus.
Q: Should people assume that this is more easily transmissible than the flu or common cold?
LW: The data on that are also continuing to come out. I think what we know is this virus is pretty transmissible, but it actually does not seem to be more transmissible than the flu or a cold.
When we’re testing for this in our hospitals and clinics, we’re also testing for the other viruses like influenza, and we are finding those viruses in very large numbers when we look for them. This virus does not seem to be more transmissible than the other commonly transmitted respiratory viruses. Those viruses are very common.
Q: Do you know of a good website that would list the survival rate or time on given surfaces?
LW: The CDC website actually compiles a lot of information. For those who want to know exactly what’s been shown, a quick web search will bring up the New England Journal article and the information from that. It’s widely quoted and available, so I think people will be able to find it pretty easily.
Q: Social distancing — does that distance account for wind or is it kind of a made up number?
LW: It’s not a made up number, it’s more of a practical number, the real number is actually more like 3 feet. These droplets are pretty heavy, so when you look at how far it’s likely to go when someone coughs, it’s not very likely to go more than three feet, but at the outside edge of that is six feet so there’s already some built in wiggle room. If you use that as an estimate I think that you’ll be in good stead, and if you’re worried about a windy day you can always give it a little more. It’s really just not being right up next to someone.
Q: Do you have any sense when testing will become more widely available?
LW: As people may or may not be aware, testing has become much more widely available than it was even a week ago and especially more than two weeks ago. Depending on where people get their health care, they may still find that their clinic isn’t testing or have trouble finding the tests, but the tests have become pretty widely available.
Sometimes, people might want to get tested even though they don’t have symptoms because they’re worried, most systems right now are focusing on testing people who have symptoms. The other thing that people may have heard that I think is really a concern is whether we’re going to continue to have all the things that we need to continue to scale up and do testing.
There are some concerns about the swabs being in short supply, and also the liquid this gets transported in being in short supply. People are furiously working on that and also looking at new tests, like blood tests, that might be available relatively soon. Testing has very much improved from where it was, though it’s still not quite where it needs to be, and it’s probably going to be changing in the next few weeks.
Q: If I’m asymptomatic, how long am I contagious?
LW: I’m not going to fully answer this question, but for people who test positive who are known to have the disease, there are two recommended ways for knowing when you’re not infected anymore. There’s a way called the ‘non-test’ version and a way called the ‘test version.’
With the ‘non-test’ version, you need to be at least seven days from the onset of your symptoms and your fever has to be gone for at least three days without taking a medicine that reduces your fever, and you have to be feeling better. If all those things happen, it’s thought that you’re not infectious anymore.
With the test version, after a period of time has elapsed, you get swabbed again — you get two swabs 24 hours apart and after both of those come back negative it’s assumed that you can’t transmit anymore.
In terms of the swabs, we know that we can detect the RNA, the presence of the virus, for a pretty long time after people have been sick, but that may not mean that they are still infectious. That can detect whether or not a virus is still alive and whether or not it can infect other people. If it’s gone, presumably you can’t infect anyone, but some people who have that test being positive probably can’t infect anyone either.
Q: Last question, can sanitizing UV light systems already installed in hospitals be used to sanitize the used masks and gowns to extend the life of PPEs?
LW: People are looking at this very actively, the University of Nebraska has been a real leader in pioneering this. People are very actively looking at this and seeing how it will work, as well as other methods like chemical methods to disinfect PPE. There are not many data points yet and there are some logistical challenges in making sure that your PPE or your mask is appropriately exposed to the UV light. You actually have to make sure all the surfaces are exposed, so it may not always be the most straightforward processes but many places are looking to see if this will work for them.