I am Dr. Ellie Murray, assistant professor of epidemiology at Boston University School of Public Health. I research the control of disease patterns in human populations. Specifically, my work is centered on improving evidence-based decision-making by patients, clinicians, and policy makers. In recent months, I have zeroed in on understanding the spread of COVID-19. I developed a spectrum of risk and harm reduction tips for every setting – from seeing friends and family, to traveling, to medical appointments and more – in an effort to help people choose low-risk activities that are sustainable in the long-term.

Ask me anything about:

  • What are the risks of returning to everyday activities? ◦ How can I evaluate the risks of different activities?
  • How can I see family and friends safely?
  • What do the COVID-19 numbers in America mean?
  • Is it safe to travel?
  • Should I go to the doctor/dentist – or reschedule?
  • Should I go to restaurants?
  • Can I safely return to the gym?
  • How long will social distancing last?
  • What does “herd immunity” mean? Is it a good solution to address the pandemic?
  • How can we improve COVID-19 testing?
  • Are there certain activities that are legally allowed during reopening that I should still avoid because they’re high-risk?
  • What are the best types of masks for exercising, returning to school and/or work, traveling and more?
  • What are the most important precautions for preventing the spread of coronavirus?
  • Where can I find the most accurate, up-to-date information on COVID-19?
  • What should I do if I’m experiencing COVID-19 fatigue?

I have been quoted in news stories covering these topics in publications including Wired, Business Insider, Vox, U.S. News & World Report, The Washington Post, Newsweek, Politico, The Atlantic, New Scientist, Slate, The New York Times, Medium, The Boston Globe, and more.

I was previously a postdoctoral research fellow in Epidemiology at the Harvard T.H. Chan School of Public Health. I have an ScD in Epidemiology and MSc in Biostatistics from Harvard, an MPH in Epidemiology from Columbia Mailman School of Public Health, and a BSc in Biology from McGill University.

Proof: https://i.redd.it/2zwzlrdxy6i51.jpg

Thank you everyone for writing in – this has been a wonderful conversation! You've all asked really important questions so I will try to come back and address those questions that I did not get to today over the next week, but unfortunately I have to log off for now. In the meantime, for more on my public health perspectives follow me on Twitter at @EpiEllie. Stay safe and be kind to each other. We're all in this together.

Comments: 848 • Responses: 46  • Date: 

uisce570 karma

Is there a single location we can use as a resource, where you’ve already answered your sample questions? Thank you.

epiellie644 karma

This is a great idea, but I hadn't thought of it before now. I'll put something together after the AMA and come back with a link.

edmar10381 karma

What do you think of the CDC's new guidelines to not recommend testing to asymptomatic people even after they've had close contact with an individual who's tested positive?

This doesn't make sense to me when the CDC's own best estimates say 40% of people are asymptomatic, asymptomatic individuals are about 75% as infectious as symptomatic individuals and 50% of transmission occurs prior to symptom onset.

https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scenarios.html#table-1

epiellie939 karma

I am very unhappy about these new guidelines. The CDC's recommendation is based on the fact that a negative test doesn't guarantee that someone is uninfected (which is true), but then erroneously assumes the purpose of asymptomatic testing is to diagnose people. In fact, as I explained in an earlier reply, the purpose of asymptomatic testing is to interrupt transmission chains. We know that people can transmit when not (yet) symptomatic, so we should be testing asymptomatic people. In the absence of testing, we should be quarantining asymptomatic individuals for 14 days following exposure. The new CDC guidelines recommend neither and this will directly lead to worsening of our ability to control COVID.

cbforest319 karma

Hi Dr. Murray! With many of us hitting months at home, people (myself included) are getting depressed, cabin fever, etc., do you have any safe travel tips for anyone looking for a short escape?

epiellie565 karma

If you have access to your own vehicle, then day trips to less crowded areas are absolutely the way to go. This is what I've been doing and it's a great way to shake off the lockdown blues. If you need a bit of a longer escape, the hotel industry does seem to be taking transmission seriously -- they want your business so they want you to feel safe. My advice, call around to find somewhere that can tell you whether they have HEPA filters (good), or windows that can open (also good). Ask what changes they've implemented to reduce transmission. If they can give a good detailed answer, then you're probably safe to stay there. If you do decide on a hotel, I'd recommend staying multiple nights in one place versus one night each in multiple places. Also remember that best practices are to do a 14 day quarantine before you go to a new place (so you don't take the virus there) and after you get home (so you don't bring it back).

bryanlogan268 karma

Given the choice between flying to visit someone and be there in a few hours, or driving and having to stay at a hotel along the way, what's the best choice?

epiellie451 karma

This is a question I've been asked many times and I go back and forth on the right answer, but the reason is that there isn't a clear aspect of either approach that makes it safer or more risky. Both have risks and both have benefits. My advice: choose the one that makes you feel more comfortable, because less anxiety & fear is better.

willwheels254 karma

If I wear a mask for five or so minutes to drop my kid off at daycare, then get back in my car and take it off, do I still need to wash it or can I wear it again?

epiellie497 karma

Ideally, you'd wash a mask whenever you wear it but let's face it that's unrealistic. If you're only wearing the mask for a short period, you have a couple other options. (1) assume it's not dirty & just take the slight risk of wearing it again; (2) hang it in the sunshine for a little while so that if there was anything on it, it gets degraded -- what a 'little while' means is not really well specified but every extra minute reduces the chances there's any virus on your mask.

Besstifer161 karma

I've been living with my ex throughout this whole thing, I finally asked him to move out but I live in constant anxiety because: 1. He doesn't take this seriously and is constantly going out to bars, hanging out with different people, and not wearing his mask. 2. Wakes up every morning and coughs all over the kitchen and communal space.

What can I do to mitigate my exposure? I know he's putting me at risk but how much?

I try to avoid him like the plague (haha) when he's home and clean the house every other day or so making sure to clean the counters in the kitchen especially.

epiellie236 karma

Housemates are making the pandemic stressful for a lot of people, so know that you are not alone, and you're not being unreasonable in your concerns. If he is not going to take the same precautions you are, then he is putting you at risk beyond your comfort level. If it's possible, you may want to consider moving out yourself.

booboolurker142 karma

Hi, thank you for hosting! I really do worry about dental appointments. I’ve had a few during this pandemic and thankfully have been fine, but my high risk mother now has a series of dental appointments and I’m worried for her. She doesn’t take the same precautions I do, and I can’t be in the room with her. Should I be worried? And should people quarantine after dental appointments?

epiellie258 karma

In my opinion, dentist visits are essential medical care -- the main difference between dentists and other medical care is that usually it's okay to put the dentist off for a few weeks or months. But eventually, if you don't go to the dentist, dental issues can develop into more serious medical issues. So, based on that, I encourage people to still go to the dentist. Quarantining afterwards is a good idea, and if someone is high risk it's a good idea to discuss that with your dentist -- they may be able to have her come in as the first patient of the day for example. It can also be useful to track your local COVID case numbers and schedule appointments for when they are relatively low -- the fewer cases in your community, the lower risk any activity is.

mmm_toasty107 karma

Hi Dr. Murray, thanks for hosting this AMA!

One of the biggest issues I've had in discussing COVID-19 with family and friends is trying to explain to them the importance of wearing masks and social distancing. Do you have any tips on communicating these things effectively to people who aren't very receptive to listening?

Also, do you have any tips for someone who's likely going to be applying for epidemiology postdocs in the next couple of years?

epiellie220 karma

This is such a hard thing to explain to people who don't understand it, because it's become so politicized. I try to help people understand that by distancing and wearing masks they are making a choice to keep themselves, their families, friends and neighbors safe, and that it's not something they are being forced to do for no reason. I also find it useful to explain that it isn't about being 100% safe versus 100% dangerous -- the goal is to be able to do those things in life that are most important to you, whilst being as safe as possible. So, if you love to run but can't bear to run in a mask find somewhere that's off the beaten path where you won't encounter others and run there, maskless. If you really need to be able to spend time with your best friend, do that but then both of you wear a mask.

In terms of explaining why this is necessary, I like to ask people to picture a spray bottle. If I held a spray bottle up to my face and squirted it at you, how far away would you have to be not to get wet? Wouldn't you rather be far away than closer wearing a mask? But if you are close enough to get sprayed, wouldn't you rather have a mask?

As for epidemiology postdocs, I encourage you to participate in #epitwitter and get to know some of the epidemiologists there. Having a network is really useful for securing a postdoc because often they aren't posted as job ads. It also will help you get to know epidemiologists on a human-level and having a postdoc advisor that you get along with well is so important! Good luck!

risketyclickit104 karma

When will this be over?

epiellie243 karma

The most similar modern comparison we have is the 1918 influenza pandemic. That took several years for the virus to stop being a problem, but the first 18 months or so were the worst. Since we seem to be responding to this pandemic in similar ways, that's probably a reasonable guess.

PHealthy103 karma

Hi and thanks for joining us today!

  1. What are the main benefits of COVID asymptomatic testing?
  2. Should universities depend on the behavior of 18-22 year olds in order to prevent COVID outbreaks?
  3. What's been your best purchase since social distancing began?
  4. Any chance for a Tweetorial on Bayesian analysis?

epiellie221 karma

Hi, these are good questions.
1. The reason to do asymptomatic testing is to interrupt the transmission of SARS-CoV-2 (the virus that causes COVID). We have pretty good evidence that people can transmit this virus before they develop symptoms and maybe even if they never have symptoms at all. So testing people who may have been exposed, including routine testing of people who regularly interact with others, can help identify people that might be transmitting but wouldn't be detected only by symptom screening. This also means that asymptomatic testing is only useful if it's paired with isolation of people who test positive and contact tracing.
2. Universities shouldn't be depending on the behavior of anyone to prevent COVID outbreaks, because outbreaks aren't the fault of individuals. They happen because our systems are vulnerable to them. In some university settings it may be feasible to change the systems enough that the probability of an outbreak is low, but in most it is unlikely that enough can be changed to guarantee no outbreak.
3. My best purchase since social distancing was a car. I'm a city-dweller and this is the first time I've ever owned one, but it's been a huge help to be able to drive out into less densely populated areas for some fresh air and exercise.
4. I'm a pretty hard-core frequentist to be honest, so the chances of a Bayesian analysis tweetorial are low :D

Achilles29185 karma

Hello Dr. Murray. Been following you on twitter for several months now. Thanks for your constant engagement and informed perspectives.

Our family has made the difficult decision to homeschool all our children as we are fortunate enough to be able to. My question, how long can we realistically expect to be in this homeschool situation? Is a vaccine the only answer? Will some sort of inflated seroprevalence, such as New York, maybe happen before a vaccine?

Thanks so much Dr. Murray. Your continued engagement along with so many other wonderful doctors on twitter help guide us when MSM can be so misleading.

epiellie143 karma

This is really difficult to answer because it really depends on what we as a society decide to do. It is possible to be more confident about opening schools by prioritizing them over, for example bars, restaurants, amusement parks, office buildings. It's also possible to be more confident about opening schools by ramping up testing and providing support for quarantine and isolation when someone tests positive. Without these things, I believe we can expect the number of cases to increase through the fall and winter. My advice: plan for a full year of home school. Hopefully, it won't be that long but probably better to be prepared for the long-haul than be expecting this to end soon

hafilax34 karma

Do you have any advice for teachers in the classroom up to grade 7? What should teachers so to protect themselves? What are the best strategies for managing the children's safety while still interacting closely with them to effectively teach?

epiellie106 karma

Teaching younger kids in the classroom is going to be so challenging. Best practices suggest wearing masks, keeping 6 or more feet distance between everyone, frequent hand washing, and limited sharing of objects. That certainly doesn't look like any elementary school classroom I've been in. My feeling is that the key will be working with the kids to help them understand what's going on and why the rules are in place so that they feel like active participants. Spending time each day answering kids questions and addressing their concerns related to the pandemic will probably be an important part of this year's education system.

heidismiles78 karma

What should we be aware of when purchasing a reusable mask?

I recently bought one that was made of jersey (t-shirt fabric), and it's super comfy, but ... I'm afraid it's not doing much. I heard that if you can blow out a match, then the mask is no good.

epiellie217 karma

When buying a reusable mask, look for one that has multiple layers -- ideally 3 or 4. Cotton or cotton blends seem to be good; t-shirt fabric can be good if the weave is tight enough (can you see through it? if so, that's no good!). Another thing to look for is masks with a wire or similar on the bridge of the nose. This lets you adjust the fit so that it's snug against the top of your face and you aren't just blowing air out over the top of your mask. Similarly, you want a mask that fits snugly against the side of your face too.

Lastly, avoid the masks with valves. Those aren't made for infections.

randomrealitycheck58 karma

Following up on that last question, should buildings which see a steady trafficking of people be doing more to ensure they are getting multiple daily air exchanges? Should we be looking to mandate better HVAC systems in these facilities, possibly including HEPA filters or possibly ionizing the air.

This study seems to indicate this might be part of a good solution moving forward.

https://www.researchgate.net/publication/226318339\_Experimental\_study\_of\_nanoparticle\_penetration\_through\_commercial\_filter\_media

epiellie165 karma

There's definitely evidence to suggest that coronaviruses can move through building air systems -- we saw this with SARS in 2003. The unknown is how big of a contributor this is to transmission, and one of the things that has made this hard to study is that so much of the population stayed home during the spring. HEPA filters should be able to remove the virus from air circulation, and so certainly many people are pushing to install those wherever possible.

Another way of looking at the question though is to consider what we use those spaces for, whether we need to use these spaces in this way, and whether there are other options that allow people to be more spread out. In the early 1900s, society made massive changes to the way cities and buildings were organized in order to combat water-borne diseases and diseases with fecal transmission. IMO, we should be thinking creatively about whether and how to restructure our lives to combat respiratory diseases. There's no real reason we need things to continue they way they always have!

Shaunie199656 karma

Hi, so I've been visiting my grandparents as sparingly as possible, and not at all if I've had contact with anyone outside my household in the last 2 weeks, is there anything else I should be doing to minimise the risk to them? Thanks for your time :)

epiellie78 karma

It sounds like you've been doing this exactly right, in terms of what's possible at the moment. In the future, if it's possible to access rapid tests (especially home tests) that can detect asymptomatic infection, that would be a good addition to be extra safe. But right now that's not something we have readily available.

CAlawyermommy55 karma

We have a nanny/housekeeper that only works for us. She lives with her husband who works outside the house as a window installer (so there is exposure).
We have been paying her her not to come since March. With school starting, and work picking up, I am desperate for some help at home with cleaning and laundry, but it's difficult to leave the house for an entire day.

If she comes in for a 3 hour block, in a mask and stays distant when she cleans (not in same room), she is upstairs when we are downstairs, etc. Is this a safe option or should we really be outside of the house when she is here?

Sorry I just don't know my ass from my elbow at this point and all the articles on household help contradict each other are blending into one scary mess.

epiellie89 karma

You're probably okay to have her come under the conditions you laid out. An extra precaution you can take is to open up the windows so that the air in your house is kept fresh before, during, and after her visit. I would also recommend that you try to reduce your contacts as much as possible before having her come over so that you don't expose her to any extra risk.

maskonbackwards52 karma

How has this changed your own personal daily family routine with the knowledge you have?

epiellie156 karma

Since March 11th, I've only been into my office three times, whereas I used to work entirely from my office. I also used to travel once or twice a month to give talks or teach workshops, and I haven't done any of that. So, my daily routine looks a lot different. On the other hand, working from home means I get to enjoy a leisurely morning coffee with my family, and we can eat lunch together almost every day. These are definitely silver linings for me.

Datazymologist47 karma

I've been trying to figure out a "contact budget" based on an idea you shared on Twitter. Problem is, I feel like I have no frame of reference for what kind of budget is reasonable! Are there any resources for helping us figure out how much person-to-person contact risk is a reasonable amount for us to take on?

epiellie82 karma

This is definitely the tricky part of a contact budget, but I'm glad to hear that the concept has been useful for you. Everyone is going to have a different set of circumstances to consider, and a different tolerance for risk, so there's really no one single number that works. That said, something I've been recommending is that people try to keep a detailed contact diary for a few normal days as a baseline. Then, work through your diary to see how much risk you engaged in over the course of those days and think about whether it's a level you're comfortable with or not. Remember that the goal is to keep your average level within your comfort zone. So, for example, after I went to the dentist (higher than normal risk for me), I stayed home completely for several days so that the risk was balanced out.

randomrealitycheck42 karma

My question has to do with suspended micro-droplets carrying viral particles in the air and also reaches into the idea of aerosol transmission.

It’s my understanding that in indoor situations these micro-droplets remain suspended in the air for as long as an hour after being shed. However, aerosol dispersion is reported to last somewhere between four to six hours.

Would it make sense to schedule shopping trips as early in the day as possible to take advantage of what may be considered less infectious air?

https://www.pbs.org/newshour/health/aerosols-may-play-a-larger-role-in-covid-19-transmission-than-previously-thought

epiellie102 karma

This is part of the rationale behind having special early hours at grocery stores for elderly individuals -- the idea is that the store is cleanest in all ways when it first opens and so the most vulnerable should be given the chance to shop then. For everyone else, if you're wearing a mask, not spending too long in the store, and the store is relatively spacious (for example like a typical suburban grocery store), then you're probably better off choosing a time when there are fewer people currently in the store rather than trying to choose a time when there have been fewer people over the past several hours.

BruceMatsunaga41 karma

Thank you for doing this AMA. I know going to the gym ranks rather high on COVID-10 risk charts since it is indoors and people are taking deep breaths, but how risky is a trip to the gym? My gym finally is requiring mask use and is limiting the number of members in the gym at one time, but I went to see what that looked like and because of this gym's layout there are concentrations of people in certain areas because of the layout (I decided not to workout). Would you go to a gym at this time? If so, what qualities or precautions would you take? I'm in AZ, so our Rt is relatively low, but my county is reporting in the mid teens for PCR positivity.

epiellie71 karma

Right now, I'm not going to the gym. My local gym is quite small, and so although they are limiting the numbers of people inside at one time, I don't feel comfortable. On the other hand, some gyms are in quite large, spacious areas -- with few enough people inside I could imagine being comfortable working out in a gym like that as long as my local case counts were relatively low. A PCR positivity in the mid-teens sounds like you're local situation is still quite severe though, especially if testing is not restricted only to the symptomatic.

BabaBoHigh40 karma

My wife teaches 8th grade at a public school in Massachusetts. They've decided on in person teaching starting in a few weeks. The teachers will wear masks and face shields and the kids will be masked. Her school is very old with poor ventilation. She's very nervous and is considering take a year unpaid leave. She is otherwise young and healthy with no comorbidities. Is her fear justified and commensurate with the risk posed in the classroom?

epiellie89 karma

There is risk associated with being in the classroom, and for your wife, it does sound like that risk is higher than if she were teaching remotely. And because of that, it's entirely reasonable for her to decide that risk is above her personal threshold, especially since this very same activity was judged too risky by the government only 6 months ago. I recommend that she try writing down all the activities she has engaged in over the spring and summer and think about whether they were more or less risky than she feels the classroom will be. If more or roughly the same, then she is maybe more concerned by feeling pressured to take on this risk than by the risk itself. If the activities she chose for herself were consistently less risky, then she should be guided by her risk tolerance level.

IamSortaShy27 karma

Thanks for the AMA!

Do you think that lap swimming in a public or health club pool is safe?

I wonder about going through the slip stream of someone ahead of me that is forcefully exhaling though their nose.

epiellie62 karma

Chlorine likely destroys the SARS-CoV-2 virus, so my main concern about pools are the surrounding surfaces and shared areas (changing rooms, lockers, etc). On the other hand, I'm not aware that anyone has directly tested the impact of pool chlorination on the virus. I know some pools are limiting the number of people who can swim at one time. My recommendation: find one that is keeping the number low, arrive in your swimsuit, and try not to touch surfaces outside the pool.

yummcupcakes21 karma

My boyfriend lives in ireland and I live in the states. I havent seen him in 2 years and before covid had planned to visit in January. Ireland is still open to travelers but I work in the medical field as an RN in an ICU and I feel selfish even thinking about going to see him. Id have a house to stay in and wouldn't be doing any traveling while I'm there, but I still feel like I would be putting people at risk. Am I wrong for feeling like I shouldn't go or do you think if I take the right precautions, all will be okay?

epiellie45 karma

You aren't wrong for wanting to go and you aren't wrong for feeling like this is potentially risky. But, if you can quarantine for 14 days before traveling, then you can minimize the risk of infecting others if you happen to be asymptomatic. My understanding is that Ireland also requires a 14 day quarantine on arrival, so it's a good idea to find out whether that's the case before traveling -- you'll need to plan for quite a long time off work if you need to do 2 sets of quarantine!

orangekrate17 karma

How hopeful are you about the use of UV light to kill virus particles in HVAC systems and room air filters? A friend who is a scientist at a major university seems hopeful about it's use.

epiellie43 karma

UV light can destroy viruses. It can also destroy anything organic (including people -- that's why we get sunburn & skin cancer). The evidence suggests HEPA filters are probably sufficient to trap virus particles, so adding UV irradiation of the HVAC system seems like it would be both unnecessary and potentially unproductive -- for example if the UV light causes the system to break down more rapidly.

jonzgreenberg17 karma

What's the risk of transmission when biking? I don't wear a mask, and there's always at least 4 feet between me and other bikers or joggers.

epiellie47 karma

There's nothing special about biking that prevents transmission, except that you are generally not close to people. If possible, I would try to be more like 6 or 10 feet away from people and if cycling in a group, it's probably better to space out as much as possible. But distance is as good as or better than masking, so if you're not close to people you don't really need a mask.

Skapunkdh17 karma

I live in a tourist town (Charleston, SC) and play music. I've not played since March, but my band is starting to book gigs for September and I'm on the fence. With social distancing and wearing masks, is it safe to be going out and playing at bars and restaurants right now? I have two immunocompromised people in my household and we've been really careful but I'm getting to the point where I could really use some of that "side gig" money.

epiellie51 karma

With immunocompromised people in your household I would advice against playing gigs inside bars or restaurants. The risk of transmission in bars, especially, appears to be quite high, and as a musician you will need to spend quite a long time in the establishment. That said, if you can find places with outdoor patios / beer gardens so that you could be outside, that might be more reasonable. You'd still want to make sure to keep physical distance from the patrons and staff, and try to avoid touching shared surfaces.

strayaares16 karma

How long is a safe time to be in an enclosed room or alternatively a room with an open door with other individuals? (with no mask on)

epiellie39 karma

There isn't a safe time, but the more time you spend in an enclosed area the more risk you have of being infected. The only way to be completely safe is to avoid these situations entirely.

aykray15 karma

What precautions would you recommend for someone who has to go for an ENT (ears, nose, throat) appointment where the mask might have to be taken off for checking?

epiellie30 karma

Medical care is important to continue with, even though it is a higher risk activity. Doctors generally understand the risks and their patients concerns, and probably share them. My advice: call the doctor and ask what precautions they are using. Some have people wait outside the building until the doctor is ready to see them; others have plexiglass barriers; often they will do temperature checks and symptom screening. As with any other higher risk activity, it's a good idea to stay home for a few days afterwards (ideally 14 days, but we can't all do that).

See-My-Eyes15 karma

Hi, Dr. Murray

  1. Do you have any information or insight about how to reduce risk (aside from preventive measures) for persons whom have to go out and are in the vulnerable group due to preexistent diseases?

2.How can you cope with Covid-19 burnout, and what are ways to detect it in others and provide support?

3.Do you know of a study regarding forecasting of the Covid-19 that has been proven as a stable model, or a way computer scientists can help to build such model?

Thanks in advance!

epiellie27 karma

  1. I'm not quite sure I understand your first question because anything you do to reduce risk is by definition a preventive measure, but I'm guessing you're asking about things other than masks, hand sanitizers, and physical distancing? If so, some other things to consider: reducing the amount of time you spend around people you don't live with, trying to be in less crowded areas, and opting for outdoors over indoors whenever possible. Beyond that, there's really not much we can do.
  2. COVID burnout definitely seems to be a real thing and to be honest I think we all have it to one degree or another. I think the important thing is to try to be open with our friends & family about what we're feeling and what they're feeling, and be compassionate with each other. If someone seems to be disinterested in things they used to enjoy, starts expressing feelings of helplessness or futility, or sleeping or eating a lot more or less than before, those may be signs that they are struggling & good times to try to gently reach out.

  3. Forecast models are something everyone wants to see but not actually something that is possible to do -- in fact, the current state of the art is what we call "nowcasting". That is, modeling how many cases there are TODAY. This is hard because our tests only tell us about how many cases there were among people who got tested at the time they got their test (which was in the past). Modeling that requires understanding who gets tested, when, and why, and all the things that delay results of testing. Forecasting for infectious diseases is not like forecasting for the weather because we can actively change what we do to respond to a disease forecast in a way that alters what will happen with the disease. In many ways, the purpose of epidemiologic models of disease spread is to change the future not to predict the future.

SmileThis958214 karma

I work in a nursing home. On the first of September they are planning to return everyone to the dining rooms for meal time. They will have multiple people to a table and no masks to enter the dining room. Staff will wear masks and face shields to bring out food and drinks. I live in a city where we are in the “red zone”. Is this safe?

epiellie36 karma

This does not sound safe, unless there is absolutely no one leaving or entering the nursing home. Presumably staff go home after their shift and so having everyone in a common dining area during a period that you city has high COVID levels sounds like a recipe for an outbreak.

Lotti7713 karma

Hi Dr Murray,

What are you thoughts on air travel and specifically long journeys (over 6 hrs)?

Airlines now request a proof of a negative Covid test taken within 72hrs but does this make a difference? Could someone have been affected after the test was taken?

I read somewhere that the air in planes is extremely clean so the infection risk is mostly before and after getting on the plane. Would love your input.

Thank you!

epiellie27 karma

Airplanes seem to be relatively safe. Having everyone give proof of a negative test is a good precaution but as you say it's not a guarantee that no one on board is infected. Still, from what we've seen, masks and partially empty planes seem to be sufficient to prevent large-scale air travel related outbreaks. So, either it's unlikely that people get infected on planes (for example because of air filtration), or the precautions airlines are taking are good enough to prevent transmission.

nrith13 karma

How effective is washing masks? How long can the virus live on an infected mask surface?

epiellie30 karma

Washing fabric masks is highly effective as long as you use soap. The virus starts to decay as soon as it lands on a surface, and decays faster on surfaces like fabric and cardboard compared to surfaces like metal, glass, and plastic. In general, it's probably possible to still find virus on a fabric mask up to about 24 hours after it was contaminated but a less contaminated mask would be virus-free sooner, and a more contaminated mask would be virus-free later. Washing it in soap and water removes the virus straight away -- you just need to make sure it's thoroughly lathered up with bubbles and then completely rinsed (or use a washing machine).b

Difficult-Western91210 karma

I’m a harmonica player and teacher. I’ve been playing and instructing online, but haven’t really been able to figure out a framework for assessing risk for in person activities. My worry is there is so much deep breathing involved in harmonica.

Friends of mine who are musicians but not specifically harmonica players have started doing small socially distanced outdoor shows and some students have asked for lessons now that it is summer. I’ve tried to look at studies about the risks of singing and my town had restrictions on performances by wind instruments.

As someone who is not a scientist but is trying to figure out when it is safe to resume activities for what is a somewhat niche activity but also the entirety of my livelihood, do you have suggestions on what I should be paying attention to/learning about to figure this out?

Thank you for the work, energy and time you have put into sharing what you know with others

epiellie17 karma

This is a great question. Any activity that requires forceful exhalation is potentially a higher risk activity, because you are projecting your breath (and therefore droplets & small particles) further than when you just talk. The key question is: how far does your breath travel when you play the harmonica? One possible test is to get a very thin piece of paper and place it at varying distances from you and see how far it has to be to not move when you play the harmonica. I would then say to add a couple extra feet for good measure and require everyone stay that far apart. Being outdoors is definitely going to be safer than indoors, but a big indoor space with high ceilings (like a theater) is better than a small indoor space.

typicalcitrus10 karma

Is it safe to have a meal with family if they're sat a metre or so away from you?

And how safe are chlorinated swimming pools?

What's with the weird ampersands in the title?

epiellie19 karma

The further the better, but a meter is pretty close unless these are members of your household.

Chlorinated pools are probably reasonably safe but the surfaces around the pool and the shared common areas are potential transmission zones. Look for a pool that limits the number of people at any one time, arrive in your swim suit, and try to avoid touching surfaces as much as possible.

tootsietoot589 karma

Is using a face shield made of plastic that covers the face + mask enough to stop myself from getting covid? Are we likely to get corona from surfaces, or is it more from droplets?

epiellie20 karma

You get COVID by the SARS-CoV-2 virus entering your body through your eyes, mouth, and nose, and then your body responding in a way that actually makes you sick. We don't know a whole lot about why certain people get very sick, others only get somewhat sick, and others don't get sick at all. But we do know that the only way to be 100% sure you don't get sick is to not come in contact with the virus. A face shield + face mask is a reasonable set of precautions, but simply not being near other people can also work in many situations (especially outdoors). We don't know for sure that you can't get infected by touching contaminated surfaces & then your eyes, nose, or mouth, but it does seem like this is probably not the main way most people are getting infected. On the other hand, we have been doing a lot of cleaning of surfaces, so it might be that we are just doing a good job of preventing infections from surfaces.

Ariel_Etaime9 karma

What is a good response for anti-maskers who state that wearing masks doesn’t work because people are not wearing them correctly or changing them frequently enough?

They state that the masks themselves are dirty. People constantly touch the mask and their face during adjustment of the mask which further contaminates the mask and the user.

I try to explain that the masks still helps reduce the airborne spread of the virus - regardless of the spread via hand/mask touching. But is there something more scientific to prove this?

epiellie47 karma

When masks for all were first being discussed, I was worried that people who wore masks incorrectly could end up infecting themselves from the masks for the reasons you describe. However, we've had several months now of people wearing masks in all the ways we'd prefer them not to and we are not seeing any unexpected increase in cases numbers (we are seeing an increase but it's more clearly linked to businesses like bars opening up). As a result, I am now convinced that masks are, overall, not likely to be harmful.

I also think it's important to be clear on what the alternatives are. If we are worried that people are wearing masks incorrectly, the alternative should be helping them understand how to wear masks safely, not completely getting rid of masks. On the other hand, if someone really just does not want to wear a mask, then they need to be more extreme about physical distancing -- the purpose of masks is to make it a bit safer to share an indoor space or be physically close to other individuals. Someone who isn't going to wear a mask should be avoiding indoor spaces and other individuals entirely.

bonsjs9 karma

How safe are screened in porches for distance socializing (compared with outdoors, indoors)? Thank you.

epiellie16 karma

A screen isn't going to block the virus but it could interrupt the flow of air and air circulation is what makes the outdoors safer than the indoors. It would depend on how many people, how large the porch is, and the specifics of the screen, in terms of exactly how risky a porch is, but I would place it intermediate between indoors and outdoors.

calculatroll8 karma

[deleted]

epiellie35 karma

My preference, as an epidemiologists, is that schools would only be open for those kids that really need to attend in person, either because of their particular learning needs or because their parents / care-givers are essential workers. Since that's not the case many places, some general tips:
-make sure kids understand that sharing masks is not allowed
-be open and honest with kids about why different precautions are being taken
-when they get home, have kids change out of their school clothes right away, put them & their masks in the laundry, and wash their hands well. For kids who can adapt to this, it might be good to get into the routine of doing bath time right after school rather than before bed.

duppy7 karma

I'm in Atlanta, and I want to visit Maine. I've been reluctant to travel. When would be a relatively good time to fly? I was thinking about waiting until October. Is that too soon?

epiellie26 karma

It's a bad idea to travel from a high case count area to a low case count area, so you'll want to wait until the cases in Georgia are low. I also believe that Maine has been placing some restrictions on incoming travelers.

That said, I expect things to get worse this fall. If there is something important you want to do in Maine, you're probably better off going sooner or planning to wait until next summer.

diamondeyes76 karma

  1. Why are brief interactions less likely to result in COVID-19 transmission vs. 15 minutes interactions? It's not like the COVID germs wait 15 minutes to come up.
  2. How safe is it to go into stores (other than grocery stores)? What is the maximum about of time you should spend in one?
  3. Would you feel safe at a restaurant or bar where you are sitting outside?
  4. How safe is it to use a public bathroom? Or a bathroom in a friend's house?

SweetPeaRiaing7 karma

Not the doc but I can answer the first question!

It’s all the particles, man! When we breathe, cough or talk, we are releasing particles from our mouths and noses. When someone is sick, those particles contain the virus. Some drs think it takes as few as inhaling 1000 viral particles to contract covid. So if we are releasing 5-15 particles per breath while breathing/talking, it will take a while to breathe in >1000 particles, even assuming you breathe in every particle released. You can be exposed to a fully infectious amount of particles in less time if someone coughs or sneezes on you. You have to think about the amount of particles you are exposed to, the size of the space you are in and how dispersed they are, and the amount of time you are breathing them in. They add up over time.

epiellie14 karma

This is exactly the answer to the first question. You need to get exposed to many viral particles to get infected, plus the more viral particles you are exposed to the more likely it appears to be that you will get seriously sick.

For the other two questions, I personally have been generally avoiding stores and restaurants (except for takeout). I'm in Massachusetts where cases are fairly low, so it's not necessarily that I'm too worried I will get infected but more that the fewer people who are in public spaces the lower the overall risk for all of us. So, in general, I recommend people think about what activities are important to them for financial, emotional, physical, or spiritual health, and what aspects of those activities are needed provide that support. For me, the thing I like about restaurants is the great food I don't have to cook, so takeout / delivery gets me what I need without any additional features adding risk. For others, the thing they like about restaurants might be the feeling of being part of the culture of a place. In that case, an outdoor seating area might be a core part of the experience. That's fine if that's what you need -- just try to reduce some other contacts or risks in another part of you life to compensate.

rimeraison5 karma

Thanks for all the work you’re doing!

What can I do to reduce my risk of transmitting the virus to others or contracting the virus myself while traveling home via plane for the holidays? I’ve already decided I’m going to do it, so how do I take a harm reduction approach?

epiellie18 karma

Airplanes actually seem to be reasonably low risk for SARS-CoV-2 transmission, especially if everyone is wearing masks and the airline has left middle seats open. The bigger concern is probably the airport -- there are a lot of people you need to interact with, things you need to touch, etc. My advice there is to try to go early enough that you can choose a time when the security / TSA line looks short to go thorough security, and make sure to have hand sanitizer with you.

The other consideration is whether you will be bringing the virus with you to the airport. Ideally, in a world where there were no constraints on your time, you would quarantine for 14 days prior to flying and then 14 days after flying before seeing your family. That's obviously unrealistic for most of us, but even a few days of quarantine is better than nothing.

boifrmpsy1 karma

Are face shields necessary even if we already have face masks on?

epiellie1 karma

Not really, but they can help stop people from touching their eyes which is a potential route of infection. Glasses + a mask would also do the same though.

DaDacheBack1 karma

Favorite movie?

epiellie6 karma

If favorite is judged by which one I can watch over and over, it's probably the Lord of the Rings trilogy. Me and my dad watch that together pretty much every Christmas since it came out :D

nschider_001-2 karma

Do you eat carrots?

epiellie3 karma

Probably not as often as I should