Covid-19: What’s the objective risk to backcountry travelers?

To mitigate a risk, it’s essential to first understand it. For example, if I were planning to hike the John Muir Trail/PCT in the early-season, I’d want to know about hazardous creek crossings. And if I was planning to drink water from natural sources on that trip, I would want to be familiar with the pros and cons of purification techniques.

This fact-based approach towards risk is central to both my personal and guided backpacking trips.

So before I get to specific coronavirus best practices, let’s start by discussing what we know — and, equally important, what we don’t yet know — about Covid-19, with an emphasis on the most relevant facts for an outdoor audience.

Our understanding of Covid-19 is rapidly changing. The information on this page was accurate as of the publishing date. If you feel that it has errors or omissions, please leave a comment.

This page was last updated on May 27, 2020.


This is a four-part series of backcountry best practices in the coronavirus era, and should be read as a whole.


For most people, Covid-19 will look something like this.

The disease

Covid-19 is a novel strain of coronavirus, and is one of seven known coronavirus strains that are human transmitted. These strains are an extremely common cause of colds and other upper respiratory infections (source).

Presentation

Symptoms

A person may have Covid-19 if they have (source):

  • A cough, and/or
  • Shortness of breath;

Or at least two of the symptoms below:

  • Fever
  • Chills
  • Repeated shaking with chills
  • Muscle pain
  • Headache
  • Sore throat
  • New loss of taste or smell

Over the course of the disease, most persons with Covid-19 will experience the following (source):

  • Fever (83–99%)
  • Cough (59–82%)
  • Fatigue (44–70%)
  • Anorexia (40–84%)
  • Shortness of breath (31–40%)
  • Sputum production (28–33%)
  • Muscle aches, or myalgias (11–35%)

Headache, confusion, rhinorrhea, sore throat, hemoptysis, vomiting, and diarrhea have been reported but are less common (<10%). Some persons with Covid-19 have experienced gastrointestinal symptoms such as diarrhea and nausea prior to developing fever and lower respiratory tract signs and symptoms.

Covid-19 may have additional long-term consequences for some patients (source).

Onset

Perhaps 25 percent of those who contract Covid-19 will not show any symptoms. Determining the exact prevalence of asymptomatic carriers is made difficult by the lack of widespread testing and the inaccuracy of current tests (source).

The time from exposure to symptom onset (known as the incubation period) is thought to be three to 14 days, though symptoms typically appear within four or five days after exposure (source).

People with Covid-19 may be contagious for one to three days before they show symptoms. These presymptomatic carriers are a particular challenge to containment strategies (source).

Progression of severe cases

The median time to acute respiratory distress syndrome (ARDS) ranged from 8 to 12 days, and the median time to admission into an intensive care unit (ICU) ranged from 10 to 12 days (source).

Severity

Hospitalization

Risk of hospitalization due to Covid-19 increases with age. According to CDC Planning Scenarios released in May 2020, “current best estimate” hospitalization rates are:

  • 0-49 years-old: 1.7 percent
  • 50-64 years-old: 4.5 percent
  • 65-74 years-old: 7.4 percent
  • Overall: 3.4 percent

These estimates have been revised downwards since March, when hospitalization rates were estimated to be about two times greater (source).

Certain preexisting conditions dramatically increase the risk of hospitalization. Approximately 90 percent of hospitalized Covid-19 patients had an underlying condition, notably (source):

  • Hypertension (50 percent)
  • Obesity (48 percent)
  • Chronic metabolic disease, e.g. diabetes (36 percent)
  • Chronic lung disease (35 percent)
  • Heart disease (28 percent)

Mortality

According to the CDC, “current best estimate” for mortality rate in the US is (source):

  • 0-49 years-old: 0.05 percent
  • 50-64 years-old: 0.02 percent
  • 65+ years-old: 1.3 percent
  • Overall: 0.4 percent

These estimates are substantially lower than previously believed, which reflects the widespread testing shortage and the unexpectedly high number of asymptomatic cases. Among Covid-19 cases confirmed with testing, the mortality rate ranges from 0.1 percent in Qatar to 15.8 percent in Belgium. In the US, it’s 5.8 percent. This huge variability is a function of testing, country demographics, the quality of care, and data accuracy (source).

Like the hospitalization rate, the mortality rate increases with age. I’ve struggled to find recent national data; as of late-April in New York City, death rates were:

  • 20-29 years-old: 0.2 percent
  • 30-39 years-old: 0.2 percent
  • 40-49 years-old: 0.4 percent
  • 50-59 years-old: 1.3 percent
  • 60-69 years-old: 3.6 percent
  • 70-79 years-old: 8.0 percent
  • 80+ years-old: 14.8 percent

I’ve also struggled to find mortality data that looks specifically at underlying conditions. But it seems reasonable that the relationship between underlying conditions and hospitalizations (90 percent) also holds true for the relationship between underlying conditions and mortality.

Relative to other respiratory diseases, Covid-19 is substantially less fatal than severe acute respiratory syndrome (SARS-CoV) or Middle East respiratory syndrome (MERS), which had mortality rates of 10 and 34 percent, but still several times more fatal than the seasonal flu (0.1 percent) (source). For specific mortality rates of the influenza, refer to CDC data.

Transmission

The infectious dose is the amount of virus needed to establish an infection. Scientists do not yet know how many virus particles of Covid-19 are needed to trigger infection. Based on the global spread of the virus, it’s clearly very contagious. Two potential explanations (source):

  • Few particles are needed for infection;
  • Infected people release a lot of virus in their environment.

Early data from multiple contact tracing studies (source and source) suggest that close and prolonged contact is required for transmission, and that the risk is highest in enclosed environments with multiple people, including but not limited to:

  • Households,
  • Long-term care facilities,
  • Homeless shelters,
  • Prisons,
  • Birthday parties, weddings, and funerals,
  • Office buildings,
  • Business conferences,
  • Meat processing plants, and
  • Crowded restaurants and bars.

Casual and short interactions are not the main cause of the epidemic.

To minimize your Covid-19 risk, avoid the three C’s: Conversations in poorly ventilated Closed, Crowded spaces.

Airborne

The virus that causes Covid-19 is thought to spread mainly through respiratory droplets produced when an infected person coughs, sneezes, or spits while talking. These droplets can:

  • Land in the mouth, nose, or eye of a person nearby,
  • Be inhaled into the lungs, or
  • Introduced into the body by touching the nose, mouth, or eyes with an infected surface, like your fingers.

Spread is more likely when people are in close contact with one another, within about 6 feet (source).

Covid-19 particles have been found in finer aerosols, such as from exhaled breath (source), but it’s uncertain if these particles are sufficient to cause infection (source). In an outdoor setting, these aerosols are probably less of a concern than in confined spaces with many people and poor airflow.

Surfaces

Particles of Covid-19 have been shown to stay viable on surfaces like printing paper (3 hours) and plastic (3 to 7 days). But, like aerosols, it’s unclear if the amounts are sufficient to cause infection, and infection is entirely dependent on having a path into the respiratory system (source).

On May 20, the CDC updated its explanation for how Covid-19 spreads. It now says that surface-to-person transmission is “possible” but “is not thought to be the main way the virus spreads.”

Water and food

Per the FDA, “Foodborne exposure to [Covid-19] is not known to be a route of transmission.” The CDC agrees.

I have not found information on the transmissibility of Covid-19 in water. For good measure, treat natural sources with chlorine dioxide or a UV light, two recommended water purification techniques that are effective against viruses.

When outdoors

Scant research has been done on the transmission of Covid-19 in an outdoor setting. A study of 318 outbreaks with 1245 confirmed cases in China traced only two cases (0.16 percent) to outdoor transmission. However, the study did not account for the proportion of time spent outdoors by the study group.

Intuitively, it would seem more difficult to absorb an infectious dose while outside, because Covid-19 particles are dispersed by airflow and probably also killed fairly quickly by sunlight (source). This article discusses infectious dose in the context of hiking, running, and cycling outdoors.

Testing

Two kinds of tests are available for COVID-19:

  1. A viral test tells you if you have a current infection.
  2. An antibody test tells you if you had a previous infection

An antibody test may not be able to show if you have a current infection, because it can take 1-3 weeks after infection to make antibodies. We do not know yet if having antibodies to the virus can protect someone from getting infected with the virus again, or how long that protection might last (source).

It’d be enormously helpful if testing for Covid-19 was more widespread and accurate. But it hasn’t been; it’s not yet; and it probably won’t be in time for the 2020 backpacking season. Read this op-ed for a good synopsis of the situation.

Treatment

There is no cure for Covid-19. One drug, remdesivir, has been shown to modestly reduce recovery time (source), and was granted emergency FDA authorization on May 1, 2020.

Antibiotics aren’t effective against viral infections such as Covid-19 (source).

The CDC recommends resting and hydrating to help manage symptoms at home.

Precautions

To reduce the risk of contracting or spreading Covid-19, health experts recommend three measures:

1. Social distancing

The most effective method to reduce Covid-19 risk is avoiding close contact (within 6 feet) with others for a prolonged period of time to prevent the transmission of respiratory droplets.

The exact length of time that constitutes a “prolonged period” is not certain. Recommendations range from just a few minutes in a healthcare setting, to 10 to 30 minutes outside of one (source).

2. Wear a face covering

When social distancing cannot be practiced, wearing a non-medical mask may protect you from others, and others from you. Masks should be washed periodically.

The efficacy of homemade masks is questionable due to cloth porosity and imperfect seals (source). I thought one article described the problem well by likening wearing masks to using chicken wire for window screens, and then also citing a 2015 study that found “a lack of substantial evidence to support claims that facemasks protect either patient or surgeon from infectious contamination.” A more recent study (not yet peer-reviewed) specific to Covid-19 found evidence to support their use.

Until there is more clear science, it seems at least fair to say that a face covering might be a “better than nothing” preventative measure. And the cost and effort of compliance is minimal.

3. Wash your hands

To remove viruses you have picked up from others or from surfaces, wash your hands for at least 20 seconds with soap and warm water. Even standard soap is more effective than alcohol-based hand sanitizer, though sanitizer will also work and it’s sometimes more convenient.

Leave a comment!

  • Is this page in error, or not clear?
  • What important facts about Covid-19 have been omitted?
Posted in on May 5, 2020
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41 Comments

  1. Cola Vaughan on May 5, 2020 at 7:53 pm

    Granted that the preponderance of cases seem to involve high density, close contact and confined quarters I was surprised to read this:

    “There is some evidence to suggest that Covid-19 particles can be transmitted through finer aerosols from exhaled breath, though it’s unclear if this could constitute an infectious dose.”

    Do you have a contact in the field of infectious disease or virology or some similar medical discipline from an institution such as your excellent alma mater who advised on the wording “some evidence” ? and “though it’s unclear if this could constitute an infectious dose.”

    • Tom on May 6, 2020 at 8:57 am

      It doesn’t use the same phrasing, but the source Andrew linked to seems consistent with what he’s saying. For example, from the last paragraph:

      “Our results indicate that aerosol and fomite transmission of SARS-CoV-2 is plausible, since the virus can remain viable and infectious in aerosols for hours and on surfaces up to days (depending on the inoculum shed). These findings echo those with SARS-CoV-1, in which these forms of transmission were associated with nosocomial spread and super-spreading events”

      • Andrew Skurka on May 6, 2020 at 9:41 am

        I cleaned up this paragraph some, to make it clearer. Point is, Covid-19 particles have been found in aerosols, but they’ve yet to learn if those particles are sufficient to cause infection. Intuitively, if it were that contagious, it would seem that even opening up your house windows would be discouraged.

    • Cola Vaughan on May 7, 2020 at 2:14 pm

      OK I guess I’m going to drag this into a semantic argument for which I apologize in advance but since this is not a trivial subject….

      It seems entirely likely based on links to articles/papers cited above that aerosol transmission in the outdoors or even more open unconfined indoor areas as long as they are not heavily crowded (uncrowded big-box store vs Cameron indoor, Duke vs UNC for ex) seems highly unlikely so for most of the purposes of this article aerosols are not an issue. The difficult to avoid exception I envision would be transportation to the activity.

      The wording as edited aboves states: “Covid-19 particles have been found in finer aerosols, such as from exhaled breath (source), but it’s uncertain if these particles are sufficient to cause infection (source).”

      The last “source” (The New England Journal of Medicine) states: “Our results indicate that aerosol and fomite transmission of SARS-CoV-2 is plausible, since the virus can remain viable and infectious in aerosols for hours”

      The cited article also states: “These findings echo those with SARS-CoV-1, in which these forms of transmission were associated with nosocomial spread and super-spreading events, 5 and they provide information for pandemic mitigation efforts.”

      So in effect events involving relatively many people in relatively confined spaces… Like a phone booth for 3 or a volkswagen for 8 or a small plane for 8 or…. there’s a reason all those people at the Choir Practice in Washington State got infected and ditto the meat-packing plants, nursing homes and prisons.

      It certainly seems “plausible” that covid 19 could be transmitted by ‘finer” aerosols in a confined space with limited air circulation.

      • Andrew Skurka on May 7, 2020 at 2:19 pm

        Point made and taken. I think in the context of outdoor recreation, aerosols probably aren’t the problem. But true stories involving high aerosol output, high density, and poor airflow would seem to validate the prospect of contraction.

        • Cola Vaughan on May 7, 2020 at 2:27 pm

          Agreed.

    • Zach Jenkins on May 11, 2020 at 2:06 pm

      The majority studies done on these have created artificial environments in which the virus was “forced” into an aerosol through highly pressurized air. It’s also important to note that most other studies have focused solely on the hospital setting where procedures can aerosolize viruses. Translation: unless you’re conducting a medical procedure with a high chance of aerosolization (e.g., intubating a patient for the purposes of a ventilator), the chances of forcing viral particles into an aerosol is minimal.

  2. Ranger on May 6, 2020 at 4:32 am

    When comparing COVID-19 to influenza you might want to include mortality rate broken down by age groups for the seasonal flu, as well, otherwise it can look misleading. In other words, with the caveat that data for COVID-19 is very preliminary and subject to change, for those 18-49 in the 2018-2019 flu season, influenza had a mortality rate of .02%, compared to your data showing .2% for COVID-19 (10x increase). For those 65+, influenza had a mortality rate of .8%, compared to a rough average of 9% for COVID-19 (over 1000% increase). Source: https://www.cdc.gov/flu/about/burden/2018-2019.html

    I work in the tourism industry and live in a state heavily dependent on the sector. We’ve gone from one of the lowest unemployment rates in the US to the highest in just a couple months. It is definitely a challenging problem for everyone that relies on travel as a part of their livelihoods.

  3. bcap on May 6, 2020 at 7:33 am

    This is unimportant to your article and pretty pedantic, but I’d argue the statement “A study by Stanford researchers published in mid–April” is inaccurate. Typically ‘published’ refers to work that has undergone peer-review. That Stanford work was uploaded to a preprint server and hasn’t undergone peer-review. At minimum I’d call it ‘self-published on a preprint server’. In fact, the preprint has actually been revised since its original posting (two versions, Apr 17 and Apr 30), and so it has changed since it was widely reported on. This is the blessing and the curse of preprints…

    • Andrew Skurka on May 6, 2020 at 9:30 am

      Wasn’t aware of the academia nuance, but have added “self-published” to make it clearer.

    • Cola Vaughan on May 7, 2020 at 2:23 pm

      If Imitation is the sincerest form of flattery then what how about straight copying Tom’s post below?

      “Once again, I really appreciate your level-headed, thorough, and practical approach to problems. This post is better written and more informative than a lot of articles on Covid-19 that were written by professional reporters.”

  4. Carl Stammerjohn on May 6, 2020 at 7:45 am

    Great synopsis of the Wuhan flu. One correction: 2 out of 1245 is .16%, not .0016%.

    • Andrew Skurka on May 6, 2020 at 9:28 am

      Thank you. Forgot to move over those decimal points, 4th grade teacher would be so disappointed.

    • Tex Nelson on May 6, 2020 at 2:30 pm

      It is not called the Wuhan flu so why do you call it that? Use the correct names please otherwise people will think you have a certain agenda…. Use google if one doesn’t know what I’m talking about….

  5. Tom on May 6, 2020 at 9:01 am

    Once again, I really appreciate your level-headed, thorough, and practical approach to problems. This post is better better written and more informative than a lot of articles on Covid-19 that were written by professional reporters.

  6. Mark Whitcombe on May 6, 2020 at 4:17 pm

    I appreciate that this is a good documentation from a personal-orientation.
    I think there are also serious issues around carrying a Covid-19 infection into a rural area, and the resultant serious possible implications for health care in those areas.
    It is partly that critical balance between Rights and Responsibilities. I think this balance needs to be included as part of this discussion.
    I cancelled my May hiking in the south of England because of the latter reasons.

  7. Ed. C. on May 6, 2020 at 9:18 pm

    There are three things that I think that is still misunderstood about the virus that are actually still misunderstood.

    1) When the virus actually arrived. I’m hearing and reading more and more stories of people who had confirmed cases before it was wide spread. We haven’t confirmed it yet, but we believe that all three of us had it in January. If that’s the case, then many of the students in my son’s school also had it because there was a wide scale sickness going around and EVERY kid that was tested for the flu came back negative. They were diagnosed with an unidentified upper respirator infection. Just today, a co-worker said that his daughter had it in December. Not sure if they confirmed it with an antibodies test, but the doc reexamined the x-rays of her lungs and he said it looks just like confirmed cases he’s seen.

    How many people have actually already had it. Check out this article:
    https://time.com/5825030/ohio-mass-testing-prisons-coronavirus-outbreaks/
    – 78% of the inmates had it.
    Then there’s the reports of NYC having a roughly 20-25% rate of confirmed cases

    3) The mortality rate. If you take the first article, the data shows 2011 inmates had the virus. Only 12 corona virus deaths have been confirmed. That’s only 0.5%. Interestingly, you get about the same percentage if you use the above numbers for NYC with their population. NYC Population: ~8.4M. Confirmed deaths: ~14,000. Mortality: 0.1%
    The flu has a mortality rate of approx 0.1% in the USA and 4.7% world wide.

    So if the numbers are similar to the flu and many more people than were expected have already had it…then what are we doing shutting everything down. Especially trails and campsites where people WANT to social distance.

    I sure hope people really start taking a hard look at the data and make the right choice regardless of party affiliation.

    • Ed. C. on May 6, 2020 at 9:31 pm

      Sorry, my math was a little off. I should have used the number of COVID cases, which is estimated to be 2.7M. They extrapolated that number from a random sampling of testing.

      So, recalculating using 2.7M, the mortality rate is 0.5% or about the same that was found in the Ohio jail. So that’s 5x more than the flu.

      So the numbers aren’t that similar, but they are still pretty low. I still believe that these numbers need to be broadcast more then allow the US populate to determine if how to proceed.

      • bcap on May 7, 2020 at 7:03 am

        I’ll avoid any specific discussion since this isn’t the place for such things. Instead I will only say that in any crisis situation, decisions must be made. And later, when time allows it is a good idea to do a post mortem to ask yourself what you could have done better. But that can be a particularly tricky thing to do even when politics are totally absent. And to further complicate matters, the outcome of a decision does always dictate whether or not the decision was a good one. Decisions of when to turn around on a mountain are a classic example. You must always reflect based on the knowledge you had available to you at the time the decision was made. What that type of analysis ends up looking for covid is still WAG (wild-assed guess) territory IMO.

      • langleybackcountry on May 9, 2020 at 9:13 am

        5x the number of deaths caused by the flu is in now way “low.” And that is 1/10th of what is confirmed if you don’t count the likely deaths not confirmed as Covid-related.

        The other thing that gets lost is that death is not the only measure of negative outcome. It’s only the most dramatic and easily quantifiable. Everything from long-term health issues (which it is too early to assess) to financial impacts on individuals, communities, and health-care systems – aside from the loss of jobs and businesses – are all impacted.

    • Zach Jenkins on May 11, 2020 at 1:47 pm

      The biggest issue with the testing data out of New York and Santa Clara is that the tests we are using have a high rate of false positives. This makes it hard to infer what the actual seroprevalence of the virus is. This article highlights many issues with these tests: https://www.scientificamerican.com/article/what-covid-19-antibody-tests-can-and-cannot-tell-us/

  8. Jessi G on May 8, 2020 at 2:04 pm

    Great article Andrew. We will continue to practice sound risk management (we always do) and look forward to backpacking our home state (Alaska) this summer.

  9. langleybackcountry on May 8, 2020 at 2:19 pm

    “because Covid-19 particles are … also killed by sunlight.”

    This declarative statement is conspicuously unsourced. From what I have found, there is a great deal of uncertainty about this. How much sunlight? What kind of UV? For how long? On surfaces, air, and/or skin? What is the influence of the concurrent effects of temperature and humidity on its effectiveness?

    If you google “does sunlight kill SARS cov 2” you get results from “No, sunlight has not been proven to kill coronavirus” to “Sunlight Kills Coronavirus Quickly” and many degrees of uncertainty in between. To state it as a known fact without sourcing and context does not appear to meet your own standards of what we know and what we don’t know. It is pretty clear we don’t *know* enough to make that statement.

    • Andrew Skurka on May 8, 2020 at 2:32 pm

      Source added

      The most definitive study I know of comes from National Biodefense Analysis and Countermeasures Center, part of DHS, summarized here, discussed by a DHS official at a press briefing, and unfortunately immediately overshadowed by our president’s interpretation of such findings to suggest that maybe UV lights could be placed inside of people in order to kill the virus.

      • langleybackcountry on May 8, 2020 at 3:04 pm

        Here is what a BBC article (April 24) says about that:
        “However, the study results have so far only been alluded to in the briefing and a leaked report – they have not been officially published or peer-reviewed. It’s also not clear what wavelength or intensity of light they used in the study. Until we have more details and the results have been properly scrutinised, it’s important to view them with caution.” https://www.bbc.com/future/article/20200327-can-you-kill-coronavirus-with-uv-light

        An interview from the same DHS lab yesterday (5/7) there are a lot of qualifiers: “so far”, “initial results”, “very detrimental”, “most of”, etc. They also said it may not kill it on skin, even if it kills it in the air and on surfaces. https://www.kxan.com/news/local/study-coronavirus-appears-to-die-quickly-in-direct-sunlight/

        I think it is highly likely there is a negative effect as with other forms of the virus, but there are a lot of unknowns – just as there are with other aspects of the virus you talk about. You use the words “intuitively” and “probably” in the “When Outdoors” section. That uncertainty changes to “are killed by sunlight” later on, which does not reflect that uncertainty, and is conspicuously definitive compared to almost anything else in the article.

        On a practical level, if a client asks, “How long do I need to hang my sleeping bag in the sun to kill it?” what is your answer? What if it is sunny and cool instead of sunny and hot? If it was me, without better answers to those questions I wouldn’t state categorically that it is an effective method.

        • Zach Jenkins on May 11, 2020 at 1:59 pm

          The paradoxical thing is that we are seeing cases of COVID along the equator. I’m of the opinion that UV light does indeed play a role (it does with every other Coronavirus).

  10. Chris on May 8, 2020 at 3:42 pm

    Great information, and I appreciate how you have listed your sources.

    One thing I would remark on: when you talk about “mortality rates”, I think you are not distinguishing between case fatality rates (deaths rate among known infected individuals) and infection fatality rates (death rate among all infected individuals). The IFR is harder to measure, but it is the statistic of interest; and i haven’t seen anything anywhere reporting an IFR of .058 in the United States. Osterholm, who you cite elsewhere, uses a number of 0.005 to 0.01. (See here: https://www.pbs.org/newshour/show/an-infectious-disease-expert-on-the-dangers-of-trumps-non-scientific-claims)

    Another characteristic of this virus that is of interest to backcountry travelers is the “silent hypoxia” associated with coronavirus pneumonia. Infected persons will have blood oxygen levels below 90 without experiencing shortness of breath or any other symptoms. But this can be easily checked with a pulse oximeter. (https://www.nytimes.com/2020/04/20/opinion/coronavirus-testing-pneumonia.html?referringSource=articleShare)

    • Andrew Skurka on May 8, 2020 at 4:00 pm

      That hypoxia comment is really interesting. I’ll look into that, but if it’s widely considered true then I wonder if it makes sense to put a pulse oximeter in the first aid kit so that this can be measured. I’m also planning to add a no-touch thermometer as part of a daily symptom check, and this could be another easily diagnostic to have with us.

      • Zach Jenkins on May 11, 2020 at 1:57 pm

        There has been a lot of experience with patients mimicking an almost altitude sickness-like presentation. We’re not currently sure if this is due to oxygen being dissociated from hemoglobin within red blood cells or from the microvascular clots that seem to be occurring. It will likely be important to differentiate hypoxia vs. altitude sickness during physical symptom check stops.

        • Andrew Skurka on May 11, 2020 at 3:37 pm

          Without a “baseline” oxygen saturation number for each client when they are virus-free, it’ll be difficult for us to differentiate the effect of altitude on them in locations like Yosemite and the San Juan’s, versus what might be due to the virus.

          So maybe this would be a more useful diagnostic for low-elevation trips when oxygen saturation should otherwise be normal.

  11. Steven Schipper on May 9, 2020 at 1:02 pm

    Question, and apologies because I have not done the research on this myself.

    First off hello Andrew, its been some years, and thanks for the continued work you do for all of us.

    I wonder if its possible, or plausible, to make, say, a pair of gloves that can resist the virus. Akin to say a pair of jeans that have been treated with Permethrin or something. I actually question why I havent seen this discussed anywhere, unless someone has discussed it and I just havent found it yet. Do you know if anyone has even considered something like this? Not that it would help a ton in hiking, but it may help people feel a bit more relaxed about the whole idea of hiking with others.

    • Brennan on May 11, 2020 at 8:25 am

      I am not an expert, but as a nurse have experience and familiarity with infection control practices. I’ve read a little about experimental antibacterial surface treatments or coatings, but as far as I can tell, the reliability and practicality of their use on something like a repeatedly worn pair of gloves is unlikely, at least in the near future. Even as a hypothetical reality, I’d still worry that the use of such a tool would confer a false sense of imperviousness. I’m reminded of the recommendations from reliable sources against the need for (most) folks to disinfect groceries — you’re better off practicing diligent hand hygiene throughout the day, especially so immediately prior to eating. Similarly, I’d rather not trust the assumed disinfecting properties of a pair of gloves over any other mitigating behavior.

    • Zach Jenkins on May 11, 2020 at 1:53 pm

      Professor / Clinical Infectious Diseases Pharmacist here. One of the biggest issues with attempts at antiviral coatings is that they tend not to last very long. The current record is around 90ish days. I believe Hong Kong is currently investigating additional methods. I’m not sure how such a coating would hold up to the elements, though it would be a useful thing to explore.

  12. Bruce Lemieux on May 11, 2020 at 8:59 am

    Thanks Andrew, this is appreciated. This is an article from Erin Bromage, an Associate Professor of Biology at the University of Massachusetts Dartmouth. This is the first sourced article that I’ve seen that classifies the risks of getting c-19 in various environments. I haven’t reviewed all of the sources yet. Feel free to delete this post if you feel it’s not relevant or contributes to this discussion.

    https://www.erinbromage.com/post/the-risks-know-them-avoid-them?referringSource=articleShare

    • Andrew Skurka on May 11, 2020 at 9:59 am

      That’s a good link, thanks for sharing it. I was sent it a few days ago, and it’s one of the sources cited in the section on transmission.

      It’s actually been a relief to see patterns from real cases: close contact, prolonged exposure, and confined spaces. We can avoid all of those things on a backcountry trip.

      I partly wonder if the patterns we’re seeing are just a function of how people spend their time — i.e. most people spend the bulk of their time at work or in their house, so it’s natural that they’d catch it and spread it there. If they started doing studies of backcountry use, would they find it there? My sense is no, because there are other instances of similar interactions (shopping at a grocery store, running on a popular trail) that are taking place daily, and the cases just aren’t pointing to this being a problem.

      • Bruce Lemieux on May 11, 2020 at 12:26 pm

        I too appreciate the insights taken from real cases. For you (and so many other businesses), the risk associated with air travel needs to be assessed. It’s remarkable to me that air travel isn’t referenced as high risk with 90% of infections from “home, workplace, public transport, social gatherings, and restaurants”. To be on a plane is to be in close contact with others for a long period of time. I suppose a plane’s superior air circulation offsets that. A comprehensive analysis of Covid-19 infections applied to all spaces (office, school, air travel, outdoors, etc) and guidelines on how to make each of these spaces more safe is sorely needed.

        • Andrew Skurka on May 11, 2020 at 1:11 pm

          I hadn’t looked deeply into the real risk of air travel until your comment, and it reminded me of a comment my sister (Stanford PhD in microbiology) made about the HEPA filters on planes.

          This article is worth a read, http://www.nbcnews.com/id/34708785/ns/travel-travel_tips/t/airplane-air-not-bad-you-think/#.XrmimqhKiUk.

          “On average, cabin air is completely refreshed 20 times per hour, compared with just 12 times per hour in an office building. On most aircraft, air is also circulated through hospital-grade HEPA filters, which remove 99.97 percent of bacteria, as well as the airborne particles that viruses use for transport (many regional jets lack these filters). Additionally, cabins are divided into separate ventilation sections about every seven rows of seats, which means that you share air only with those in your immediate environment and not with the guy who’s coughing up a lung ten rows back. When the plane is on the ground, however, air circulation in the cabin can be greatly reduced.

          “The most common way to pick up a bug when flying, experts say, is from a contaminated surface—tray tables, lavatory doors, and latches on overhead bins are loaded with viruses and bacteria. “When I travel, I become very compulsive and even wipe the tray table with an alcohol-based hand sanitizer,” says Dr. Gendreau.”

  13. Zach Jenkins on May 11, 2020 at 2:12 pm

    Awesome job! This is very well-developed.

    • Andrew Skurka on May 11, 2020 at 2:29 pm

      Thank you. I guess you’re saying that my Duke (Economics) professors would be proud.

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