ZBiotics' microbiologists answer your COVID-19 questions
The scientists at ZBiotics are microbiologists, which means our training, education, and careers have been focused on the study of microorganisms, including viruses like the coronavirus SARS-CoV-2.
As such, we found ourselves receiving many questions from friends and family about the coronavirus and the COVID-19 pandemic. So much so, that we decided to open it up broadly, by inviting anyone to submit their questions to us on this page.
We received some excellent questions, and we wanted to share some of them – along with our answers – below.
Note that this is only for informational purposes. It's not medical advice. We based our answers on a scientific reading of publicly available data, which changes day by day. So answers are subject to change as more research becomes available. We last updated this page on April 9, 2020.
SARS-CoV-2 = the virus itself (virology/microbiology).
COVID-19 = the disease caused by the virus (medicine).
Pandemic = the global public health crisis caused by the virus (epidemiology/public health).
- Daily Life
- What's the relative risks of homemade masks - is it better than nothing?
- If I go grocery shopping, should I be wiping it all down when I get home?
- Should we be changing our clothes when we get home? Can shoes track the virus into the house?
- I heard that some dogs have tested positive. Should I be worried?
- How worthwhile is it to wear gloves? What’s Going to Happen in the Future
- Is the ability to give people DIY testing kits like 23&me a possibility?
- Based on what we know so far, is it possible that the virus returns in the fall?
- Are people truly immune after getting the virus? SARS-CoV-2 vs Other Viruses
- What is the difference between the flu and this virus?
- What's the difference between a virus like SARS-CoV-2 or Influenza – which you can be “cured” of – and something like HIV or Herpes – which stays in your body and has “flare ups”? Deeper Questions
- How effective is UV at sterilization, and is there consumer-available technology that works?
- In the trimeric structure of the coronavirus protein spike that binds to ACE2, what determines the dynamic action of the single arm hiding or exposing its binding tip?
What's the relative risks of homemade masks - is it better than nothing?
There are a lot of discrepancies and disagreements among experts about the use of masks. Part of the problem is that it is difficult to gather data about how well masks reduce risk. What we do know is that the major purpose of masks is to help prevent water droplets containing virus from being inhaled into your lungs. The smaller the droplet or particle, the less effective the mask. So masks are very effective at filtering out large droplets, such as those emitted immediately from a cough or sneeze or breath that a person in close contact might directly inhale before those droplets quickly fall to the ground. This makes sense for healthcare workers who are in close contact with sick people, and for people directly caring for someone who is sick. However, unless you’ll be in a crowded place, a mask probably won’t reduce your risk of illness all that much, since whatever you are breathing is much smaller on average, as by definition it is capable of being suspended in the air for longer periods of time.
That being said, more and more experts – and now the CDC itself – are advising people to wear homemade masks when they go out in public, as it will reduce the amount of infectious droplets you might be breathing or coughing out. While there are still a lot of unknowns when it comes to transmission, there is more and more evidence that people can be contagious even before they have symptoms. Therefore, a homemade mask is a good way for you to reduce the risk that you are walking around unknowingly contaminating others. It of course is not a 100% effective solution, but it is better than nothing and can help protect others from you!
If I go grocery shopping and people are touching all my boxes and bags and stuff, should I be wiping all that down when I get home? I've heard the virus can live on surfaces for hours.
Yes, wiping these things down could reduce your risk to some degree. For anything that can't be washed with soap, you'd need to wipe things down with 65%+ alcohol solution or bleach to kill the virus (note that this is stronger than many household cleaning products). Still, it's important to remember that good hygiene practices (e.g. washing your hands frequently, not touching your face, etc.) are probably a stronger strategy
In addition, it is important to note that while touching contaminated surfaces and then touching your mouth, nose, or eyes is a possible route of transmission, it is not thought to be the primary method of transmission (see quote from the CDC’s website below). While we do know that the virus can persist on some surfaces for hours or even days (depending on the surface), it is not totally clear how dangerous that is or how likely you actually are to be infected by that contaminated surface. We do know that the main way the virus spreads is person-to-person – inhaling aerosols containing the virus that an infected person has expelled by breathing, coughing, or sneezing. This means that while you should absolutely be careful about touching contaminated surfaces as a route of infection, it is generally lower risk than close personal contact with an infected person.
Related quote from the CDC: "It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads."
Should we be changing our clothes when we get home from the grocery store? Can shoes track the virus into the house?
Your clothing could become contaminated and thus a possible source of infection, but while it certainly can’t hurt to err on the side of caution, this is probably not an efficient route of infection and therefore not strictly speaking necessary.
And yes, your shoes could theoretically track virions into the house, but probably a very small amount. And unless you plan to spend a lot of time with your face on the floor, it would be an extremely unlikely route of infection.
I heard that some dogs have tested positive. What does this mean? Should I be worried?
To my knowledge, there have only been two confirmed cases in dogs. Generally, given how many dogs have likely been exposed, it means that the virus is extremely poor at infecting dogs, and it should not be considered a relevant risk. This goes both for the dog and for the dog as a vector to infect people. But as with any illness, if you do feel unwell, it is best to limit your exposure to your pets.
How worthwhile is it to wear gloves? For instance, I see people wearing gloves, but then touching their phones. Is there a point?
I see two advantages to wearing gloves: (1) giving you a two-step process for cleaning your hands, and (2) reminding you not to touch your face. First, your hands have nooks and crannies, so theoretically you could miss a few spots when you wash your hands, and contaminating virions could remain to infect you. So wearing gloves when you are in a relatively high risk setting (e.g. at the grocery store touching things other people have touched), and then removing those gloves when you get home and also washing your hands could be more effective than hand washing alone. Realistically though, this is probably not going to reduce your risk all that much, since touching a contaminated surface and then touching your face is not a super efficient way to infect yourself (you’re much more likely to get infected from breathing in infected droplets emitted from an infected person directly), so the small amount of virions that might still be hiding in a wrinkle on your hand is probably very unlikely to pose a serious infection risk.
However, gloves can also be useful as a way to remind you not to touch your face. For instance, when I work in the lab, I always wear gloves, and the presence of those gloves always reminds me not to touch my face while I’m working. The gloves serve as a reminder that my hands are contaminated, so I’m extremely cognizant about what I’m touching. If you think of the gloves on your hands as instantly dirty and contaminated, it’s a good mental crutch to help keep you from touching your face. You’re right that if you’re still touching your phone, you’re still spreading the virus around to surfaces that could come in close contact with your face. But if you use the gloves as a way to remind you that your hands are contaminated, it can be somewhat helpful.
What’s Going To Happen In The Future
Is the ability to give people DIY testing kits like 23&me a possibility?
At some point yes, I think this will be possible, not to mention ideal. The less that healthcare professionals have to handle potentially infectious samples, the better. Basically, it will come down to developing tests with enough sensitivity to detect virus or viral signals even in a low-quality sample or a sample that is very easy to collect (such as urine or saliva).
Based on what we know about this virus so far, is it possible that it will return in the fall?
It is absolutely possible that we could see a resurgence of SARS-CoV-2 after initially controlling the spread. However, any seasonal effects due to weather specifically are speculative at the moment, and this might not be the same kind of seasonality as something like the flu.
For one thing, so far it does not appear as though people are getting re-infected with SARS-CoV-2. So if it did resurge, it may only be in the people who hadn’t been infected the first time around. Put another way, we could see some ups-and-downs on the number of new cases, but this would likely be due to better and worse containment of the virus, not seasonality or re-infections that would continue indefinitely like with the flu. However, all this is of course assuming that the virus continues to behave as it has been, and it does not take into account any shifts in the underlying genetics that could change the virus’s behavior.
It also is contingent on the idea that people will not be able to get re-infected, which is something we don’t know in the long-term to be true. Your body develops immunological memory to the virus, which helps your body defend itself from a subsequent attack by that virus. However, we don’t know how long-lived or effective that memory is yet, beyond the few months of data we currently have.
Are people truly immune after getting the virus? People keep saying that...
So far that seems to be the case. The virus is good at stimulating your body’s immune response, and your body generates a robust defensive strategy that enables it to “remember” the virus and protect your body from future infections.
However, it remains to be seen how long this immunological memory lasts and if people can’t get reinfected for life, or just for a certain period of time. Vaccine development takes advantage of immunological memory, so knowing how susceptible the virus is to the immune system long-term is critical to vaccine efforts.
SARS-CoV-2 vs Other Viruses
What is the difference between the flu and this virus?
While there are many things that are different (and some things that are the same) between these two viruses, I’ll focus on a few things that are possibly relevant for comparing them for practical reasons.
First, they are similar in the sense that they both cause respiratory infections and are similarly spread through inhaling contaminated droplets spread from person-to-person via breathing, coughing, and sneezing. They are also less commonly spread by touching surfaces contaminated with the virus, followed by touching your nose, mouth, or eyes. So a lot of best practices and things we know about preventing the spread of flu can also be relevant for SARS-CoV-2.
However, SARS-CoV-2 appears likely to be more contagious: flu typically has transmission rates at around 1.3 (i.e. a person with the flu will on average infect 1.3 people), while SARS-CoV-2 appears to be somewhere between 2 and 3.
An important difference between these two viruses is the size and structure of their genomes. Flu packages its genome in segments, and has the ability to mix and match segments, particularly when two different strains of flu infect the same person or animal. This is partly responsible for the ability of flu to generate new strains that can escape the immune system and infect people year after year. The good news is that coronaviruses generally – and SARS-CoV-2 specifically – do not have this segmented genome. They have a single piece of RNA that is roughly twice as long as the flu genome. While this RNA genome can and does pick up mutations that could meaningfully change it, it does not have the same mix-and-match capability as flu, which makes it less likely to be able to reinfect those who’ve already been infected. This is good news for limiting seasonality and for vaccine development.
What's the difference between a virus like SARS-CoV-2 or Influenza – which you can be “cured” of after it runs its course – and say something like HIV or the Herpes virus which stays in your body forever and has “flare ups”.
The reason that we currently can't “cure” some viral infections, such as HIV and herpes, is because of their lifecycle strategy. These viruses can establish a latent infection (as opposed to an active infection), meaning they lie dormant in a long-living cell type (e.g. a neural cell... although in the HIV field the actual latent reservoir is still somewhat unknown and a very hot topic of research). However, other viruses, such as flu and SARS-CoV-2 do not have this latency ability, and can only establish active infections. They just bust in and start blowing stuff up.
The latency is a very specific feature of certain viruses that requires them to be able to infect certain types of cells and maintain “cloaking” or "stealth" features that allow them to stay there for a long time without the immune system spotting them.
To use a military example, it’s the difference between driving into a city in a tank and trying to kill people by blowing up buildings vs. sneaking into a city as a covert operative, taking up residence in an abandoned building, and then sneaking out every so often to kill people in their sleep.
The tank is like flu or SARS-CoV-2. It's intimidating, and it's going to do damage, but our immune system can clearly see it, fight it, and get rid of it once and for all. HIV or herpes is more like the covert operative; your body can't seem to find it or get rid of it, so the virus keeps popping up and creating damage before going back into hiding. It is very unlikely that SARS-CoV-2 could develop latency and establish a chronic infection like HIV, as this requires a very specific set of traits that SARS-CoV-2 does not have and would be hard to spontaneously develop.
How effective is UV at sterilization, and is there consumer-available technology that works? For example, I see online ads for phone sterilizers that use UV but don’t know what type of UV they produce and if they’re effective/harmful/etc.
UVC specifically is quite good at killing living things because it causes pyrimidine dimers, which basically ruins DNA and RNA. However, there are a few important caveats:
- UVA and UVB (and thus, sunlight) are probably pretty useless. Several studies have shown that they are largely ineffective. Maybe they kill a little bit of virus, but they are not really practical as a method of reducing risk/exposure.
- The duration of exposure and amount of UVC matter. For instance, in this study, they saw effective sterilization of SARS-CoV after 15 minutes, but in a different study, it took 60 minutes for the virus to be inactivated. The difference was that the first study used a much higher-powered UVC light source and put that source only 3cm away from the sample. This was in contrast to the second study, which placed a weaker UVC source 80cm away. Obviously, a higher powered light put closer to the virus is going to be more effective than one further away.
- UVC light can only disinfect what it shines on. This sounds obvious, but what this means as a practical matter is that shadowed nooks and crannies of your phone or whatever you're trying to disinfect with the light can be hiding places for the virus. Put another way, smoother objects will disinfect much better than something with ridges, wrinkles, and pockets. Also, 360-degree coverage of the object with light is needed. And of course, it only works to disinfect surfaces, not the inside of most substances (e.g. the inside of a box).
- UVC light is super dangerous and damaging. This means that any commercial product that is available for purchase either has a mechanism that prevents the user from being exposed to UVC, or if the person can be exposed to the light, it is probably not UVC.
As for phone sterilizers, there are probably some legitimate ones out there. In a brief search, I found this one, which specifically says it is UVC, and the light source is very close to the phone by the way it is designed. However, I can't find how powerful the light is, so it is unclear how long you'd need to sterilize your phone with it to kill SARS-CoV (and presumably SARS-CoV-2). 15 minutes? An hour? longer? It would depend on how powerful the light is.
I watched this video about coronavirus structure and infection. In the trimeric structure of the coronavirus protein spike that binds to ACE2, what determines the dynamic action of the single arm hiding or exposing its binding tip? Specifically, is it just random physical movements of the virus particle such as momentum of the molecular structure or is there some clocking process that would intermittently push exactly one tip out to check for the presence of my delicate lung-tissue ACE2 to bind to? And what makes only one arm swing out at a time? How the frick is the immune system supposed to neutralize that?
First, to be clear, we can only speculate that the flexing action of the spike protein is similar for SARS-CoV-2, since we only have actual data on other coronaviruses. But in the SARS coronavirus I could not find any data to suggest the mechanism for the "up" vs. "down" conformation. This kind of hinging action is common in proteins as a way to regulate their functions. In some cases it is random physical movement, and in other cases it is in response to some condition that is conducive for that action (e.g. changes in pH, concentration of some molecule, etc.). Either could be the case for the spike protein.
As for why only one swings out at a time, the authors of the paper that elucidated this action noted that in MERS, all three arms could be up at the same time, but that in SARS only one was ever observed up at any given time, despite there being physical space for all three to be up. They speculated that the reason could be that if multiple arms were up at the same time, it could result in protein instability and dissociation. So the short answer is that we don't know why only one goes up at a time.
However, as a practical matter, your question really is asking how the immune system is supposed to neutralize it if it's moving around and the business end is possibly hidden. The good news is that the dynamic action of the arm is not necessarily an issue for the immune system. Neutralizing antibodies can bind to several different places on the virus that are conserved, or can bind to another place on the spike protein that inhibits binding and fusion (e.g. on the hinge, preventing the "up" conformation altogether; on the cleavage site, preventing fusion; etc.).
In addition, the immune system often fights viruses in other ways besides just binding directly to intact virus floating around in your body. For example, to oversimplify another strategy of adaptive immunology a bit, cells actually grind up bits of protein in them (including viral proteins if they are infected) and present them to your immune system. If the immune system recognizes something presented on the surface of the cell as not "self" it will destroy that cell. It is one of the most common ways that our adaptive immune system protects us from intracellular pathogens like viruses.
It's kind of like when you go to Costco, and as you leave you have to give the person at the door your receipt. They check the receipt and then look at your cart and make sure there isn't anything in there that isn't supposed to be. The receipt checker is kind of like an immune cell, and if it sees something in your cell's "cart" that isn't supposed to be there, it will blow that cell up.
Given that we haven't yet seen people getting re-infected, it is reasonable to assume that your body is mounting a very effective adaptive immune response that is generating immunological memory. That's also good news for vaccine development.