The Puzzling Questions of the Coronavirus: A Doctor Addresses 6 Questions That Are Stumping Physicians

Posted on by

Yves here. While a list of coronavirus “known unknowns” is useful, I imagine most readers would have focused on other questions, like “When will we know how much if any immunity you get from contracting the virus?” However, this article likely reflects issues that seem to be coming up in layperson discussions….which in turn reflects the informational nuggets that attract media attention.

Originally published at The Conversation

Editor’s Note: As researchers try to find treatments and create a vaccine for COVID-19, doctors and others on the front lines continue to find perplexing symptoms. And the disease itself has unpredictable effects on various people. Dr. William Petri, a professor of medicine at the University of Virginia Medical School, answers questions about these confusing findings.

Some evidence suggests that patients experience low oxygen saturation days before they appear in the ER. If so, is there a way to treat patients earlier?

Even before symptoms arise, people infected with SARS-CoV-2 show damage to their lungs. This is likely why low oxygen saturation – that is, below-normal oxygen levels in their blood – occurs before the patient goes to the ER. Restoring those levels to normal is presumed, though not proven, to be beneficial; giving patients supplemental oxygen via a nasal cannula, a flexible tube that delivers oxygen, placed just inside the nostrils, will restore oxygen to normal levels unless disease worsens to the extent that mechanical ventilation is needed.

Young adults are having strokes with COVID-19. Does this suggest the illness is more of a vascular disease than a lung disease in that age group?

COVID-19 can be a devastating disease to multiple organs and systems in the body, including the vascular and immune systems. A lung infection is the primary cause of disease and death. There are examples of the clotting system being activated and causing strokes, perhaps caused by an immune system responding abnormally to COVID-19.

The Centers for Disease Control and Prevention recently updated its official list of symptoms. Does this suggest anything unusual about COVID-19?

This new information is due to a greater number of infected individuals being studied. The update simply reflects a better understanding of the full spectrum of illness due to COVID-19, from asymptomatic to presymptomatic to severe and fatal infections.

How can so many people experience such mild symptoms and others quickly die from it?

One of the most fascinating aspects of these diseases is the huge difference that individuals experience with an infection. In our own research, we have found that many children in the U.S. infected with cryptosporidia have no symptoms, yet this parasite is a major killer of infants in the developing world. After an infection of SARS-CoV-2, the severity of the illness is likely due in part to how the patient’s immune system responds; an overzealous immune response may cause death through what is called colloquially a “cytokine storm..” We do not know yet if cytokine storms occur more in one group than another – for example, older versus younger.

The disease appears now to affect various other organs – heart and kidney, for example. What does this suggest?

What we know most clearly is that infection starts only in human cells with the ACE2 receptor – that is, in a cell that is capable of receiving the virus. That is present not only in the lungs, but in other cells as well, including those in the intestine and in the nasal mucosa, which lines the nasal cavity. When those cells are infected, the immune system is activated. A consequence is that both the heart and kidney are affected.

Why are some countries not experiencing as much COVID-19 as the U.S., Europe and China?

I think it’s too early in the pandemic to know if certain countries or populations are relatively less susceptible. The younger overall age of a population could be a primary factor. Or perhaps the virus, so far at least, has not had time to spread more widely in these countries.

Print Friendly, PDF & Email


  1. The Rev Kev

    The thing about this virus is that it seems to be the Swiss Army knife of the virus world. Instead of a simple virus, as time goes along you find out that it has all sorts of weird and damaging effects in all sorts of places. And that just because you get it does not mean that the won’t get the next strain. We aren’t even sure how to treat it and financial interest are clouding the search for a treatment. It is like we just can’t get a handle on just what this virus really is or just what it does to the human body.

    1. Synoia

      The Eco-sphere strikes back?

      There are a lot of humans to infest, appears to the virus as a bountiful place to inhabit.

  2. Lee

    Differences in susceptibility to a virus is one of the main working hypotheses regarding the disease Chronic Fatigue Syndrome (a.k.a. myalgic encephalomyelitis (ME), and systemic exertion intolerance disease (SEID).

    The assumption is that the symptoms represent a relatively rare immune system over-reaction in a relatively small percentage of the population to a viruses that in the vast majority of persons is part of their normal viral load producing no symptoms.

  3. Hana M

    Yet another puzzling note on Coronavirus transmission. Sixty-six percent of coronavirus hospital admissions in New York in a recent study cited by Gov. Cuomo, were people who had been staying home. Most of the cases were elderly, and either retired or unemployed. The vast majority had other conditions. And African-Americans and Hispanics were disproportionately affected. My apologies for not linking to the original study–I’m still trying to track it down.

    It is possible that the virus is spreading within crowded and substandard apartment complexes. One possible mechanism? Toilets, as an outbreak of SARs in 2003 demonstrated:

    In addition in poorly maintained buildings just going out in the hallways to put out your garbage, for example, might well expose a home bound residents to viruses lingering on common surfaces.

    1. Bob Hertz

      The city of Hong Kong is even more crowded than New York, but last I checked its virus deaths and hospitalizations were much lower.

      1. Hana M

        Hong Kong and New York are completely different on so many levels apart from population density. The differences are more instructive than the similarities. Hong Kong had a devastating experience with the SARs coronovirus epidemic in 2003 so they had a much clearer idea what they were dealing with; much of the early response (masks, increased social hygiene) was a bottom up response by people who had gone through it before.

        The HK response to COVID-19 was also earlier, more targeted, both more draconian in some ways and much less so in others.

        Still, the two apartment building outbreaks I’ve referenced in these threads both occurred in Hong Kong.

      1. Hana M

        What a surprise! You’re on your own, says Cuomo.

        ‘“Much of this comes down to what you do to protect yourself. Everything is closed down, government has done everything it could, society has done everything it could. Now it’s up to you,” Cuomo said.’

      2. IsabelPS

        “How can so many people experience such mild symptoms and others quickly die from it?”

        There seems to be another possibility, that SARS-CoV-2 can infect both the upper respiratory tract (like the coronavirus responsible for the common cold) and the lower respiratory tract, eventually causing pneumonia (like the SARS-CoV)

      3. anon in so cal

        This is an alarming development, not least because anti lockdown GOP and Libertarian types have jumped on it to argue that the lockdowns are misguided. The news item raises many questions, such as, are the afflicted individuals getting the virus from groceries; some aspect of their domiciles, such as plumbing or ventilation; or are they permitting non-household individuals to visit them. Obviously, more detailed data are needed.

    2. PlutoniumKun

      It would be interesting to see if there is a connection between the virus and apartments/co-living.

      The one thing for sure is that this virus is extremely contagious for those who are vulnerable. A colleague of mine cocooned himself with his two elderly parents in their detached suburban house at the very beginning of this, back in late February (he could see it coming). I know he was very cautious in order to protect them. But both his parents died from it over the last 2 weeks, and he is only just recovering from it. So far as I know, he has no idea how the infection got into the house.

      1. Synoia

        Is the address data for the death available?

        It would be interesting to look for correlation between Covid deaths and the ages of the apartment complex.

      2. Hana M

        What a terrifying story! Really we are so far behind on the basic public health detective work and analysis that we need to do to beat this.

      3. rtah100

        We have been isolating since mid- March. All food delivered and disinfected, post heat-treated. Never eaten a healthier diet or taken more vitamins. Been out (beach and moor) just a handful of times, no contact, always hand sanitizer etc.

        Nevertheless, still had three colds!

        Viruses are damn infectious.

        Also, pace the Kawasaki-like syndrome in children putatively linked to sars-cov-2, true Kawasaki syndrome has no known causal agent but it is believed to be infectious in origin because it is reliably linked to wind: when it blows from central Asia, cases spike in Japan and Hawaii.

        Could Sars-cov-2 be hitching a ride on the wind / pollen and infecting people long distance?

    3. Oso

      Hana M, good post and links
      “It is possible that the virus is spreading within crowded and substandard apartment complexes. One possible mechanism? Toilets, as an outbreak of SARs in 2003 demonstrated”

      brought to mind one of the possible causes among my community (field workers). porta pottys are badly maintained as well as in short supply. among the many hazards, also particle board living quarters where people sleep in shifts.

        1. Oso

          you’re welcome Hana M.
          also, along similar lines a group of us here in oakland (with some city council buy in) are asking for a black new deal dealing with covid-19. demands are specific as well as linked to available funding. i’ll share them if ur interested.

            1. Oso

              Dear Elected & Appointed Officials,

              Two weeks ago, over 50 Black community leaders and

              dozens of our allies, reached out to you with our

              concerns for how COVID-19 is currently impacting Black

              people inequitably in Oakland and what the long-term

              consequences will be. We know that just in a week,

              Black people in Alameda County have become the most

              impacted group of people with regards to COVID-19

              infections and deaths.

              And yet, to date, we have heard no response from you.

              While any Oakland resident should expect a speedy

              response from its government officials, the list of

              signatories include some of Oakland’s most visible

              activists, advocates, policy experts, medical

              officials and formerly elected persons.

              We understand that there is a Racial Task Force to

              pull together some kind of plan and we also understand

              that there is only one Black person on that Task

              Force. There should be at least four Black people on

              this Task Force and they should be chosen by the

              community, not appointed by the Mayor.

              While remaining committed to all of the demands in The

              Black New Deal for Oakland, we are putting out four

              areas that we believe require immediate attention and


              Testing: The Mayor of Los Angeles has committed to

              free testing for all of its 10 million residents.

              Oakland has 400,000 people. We want free and

              immediate testing for all of Oakland; beginning with

              the Black residents in Oakland – and specifically

              beginning with the impacted zip codes that were

              released around East and West Oakland. These testing

              sites should also provide free masks and hand

              sanitizer for all who want them. And be equipped to do

              proper contact tracing so we can end this pandemic.

              Housing: Every unhoused person in the City of Oakland

              needs to be sheltered immediately in hotels where they

              can quarantine safely and have their basic and medical

              needs met. FEMA will replace up to 75% of the funds

              necessary to make this happen so financial strain is

              not an arguable issue. Additionally, we need rent and

              mortgage forgiveness for Black renters and homeowners.

              Incarceration: Given the disproportionate impact of

              COVID-19 on the Black community and the

              disproportionate number of Black people in jails;

              Black peoples incarcerated in Alameda County must be

              released immediately. Upon release, they must be

              tested, provided with medical care and housing and

              other necessary services. Redirect the $106 million

              each year for three years asked for by Sheriff Ahern,

              as well as, the dollars asked for by Parole and

              Probation, to organizations providing vital services

              like housing, healthcare, public education, healthy

              foods, testing, community-lead safety systems and

              other essential needs to people coming home.

              Education: As schools continue to engage in distance

              learning, the County, the City and the Oakland Unified

              School Board must work together to immediately provide

              internet access and computers to impoverished children

              who do not have this privilege. Failing to do so is

              reinforcing the already existing learning gaps and

              school to prison pipeline. The Governor called for a

              practice of social distancing when schools reopen.

              Class size reductions and additional classroom space

              will be needed to accommodate that safety protocol.

              Therefore, to meet the additional space needs a

              moratorium on school closures and co-locations must

              occur in Oakland.

              We, your constituents, expect an acknowledgement and

              response from you within seven days of the receipt of

              this letter. Our people’s lives are on the line.

              1. JTMcPhee

                Oso, I hope you are successful in getting for your community what the Fuggers in the Imperial and state capitals are denying to all of us.

                1. Oso

                  thank you, uphill struggle even with community support. no real choice with covid on top of everything else.

    4. Oregoncharles

      We’ve been having groceries and other items delivered; one just arrived. This leads to a big disinfecting operation, focused on containers, sacks, etc. I even wash all the veggies before bringing them in. It’s more trouble than doing the shopping was, but so far it’s worked. We’re healthy so far, salt over shoulder.

      Fortunately there’s minimal infection here, but it is present.

      I’m just thinking if you DON’T disinfect the packaging and then your hands, you might well introduce the virus.

    5. Ignacio

      Indeed, two weeks after a lockdown most hospitalizations must be originated in contagions inside houses or residential buildings where most direct or indirect contacts occur. This suggests that fomites-led contagions are important in Covid-19 transmission. During a lockdown, with very few getting in and out one should basically beware about touching things like doors, elevator buttons, or light switches rather than breathing contaminated air. In buildings with wealthy residents someone will be paid to keep all these surfaces clean once or twice a day but in less wealthy sites it has to be done by oneself.

    6. cnchal

      > . . . Sixty-six percent of coronavirus hospital admissions in New York in a recent study cited by Gov. Cuomo, were people who had been staying home.

      Anyone check if there is a stack of empty Amazon boxes in the corner? Every one of their warehouses has infected workers, and we all know how much people like to push the buy button and crack that whip.

  4. CuriosityConcern

    I had a thought yesterday, and it probably has nothing to do with COVID19, but remember the vaping injuries to young people last year? What if those were early infections transmitted via infected vape devices or accessories?
    Points against this being true: didn’t appear to be any spread among medical personnel treating the vape injury population.
    Final verdict if I remember right was some form of vitamin e being in the vape liquid.
    Points in favor: I thought certain quarters were not satisfied with the vit e explanation.

    Just wild speculation on my part, but interesting idea, no?

    1. Code Name D

      I remember hearing a roomer that smokers were more susceptible to covid. Not seen anything to support that though.

      1. ShamanicFallout

        It is actually now appearing to be the opposite- smoking (and/or nicotine) is something of a prophylactic. There have been several links floating around here discussing this. Not sure how definite the conclusions though.
        Also, I am untrained in any of this stuff, though have been following, but it seems that something that hits a small majority of people very hard, while so many seem to not even know they have it, says to me it’s some specific genetic issue.

  5. Hayek's Heelbiter

    Strangely enough, one possible explanation of why ethnic minorities are more susceptible to Corona virus is the same reason that Northern Europeans seem to have greater resistance to HIV. Corona virus and HIV both are single-stranded RNA viruses. (And why remdesivir, effective against Ebola [a double-stranded RNA virus] is also showing effectiveness against Corona virus).

    If you are alive today and have Northern European ancestry, they were quite likely survivors of the Black Death with a mutation that disables CCR-5 . It’s Evolution 101.

    Africa, Asia and the Americas were never exposed to the plague with the same virulence that Northern Europe was, and thus populations there did not develop the same level of of immunity that has lingered in people with Northern European ancestry.

    As this is already a plausible theory for HIV, I have been unable to find the same research on Coronavirus as to whether people who are immune to it somehow have similarly disabled receptors on ACE-2.

    1. Synoia

      How could the two Black Death plagues, the 1347one and the 1665 affect your hypothesis?

      I believe the 1347 plague was not brought to the west by sea, as it predates the Portuguese exploration of the sea route to the orient.

      1. The Historian

        There are many good books on the Black Plague of 1347 and how it originated and spread. The most common theory is that it came with the Huns as they attacked shipping ports on the Black Sea which were connected to the overland shipping routes to China. Yes, Europe had trade with the Orient before the Portuguese rounded Africa. And then the ships in the Black Sea started bringing it west to ports in Italy and beyond.

        For a simple yet historically accepted theory of the Black Plague, there is a well done course on Great Courses Plus, as well as a ton of written histories. Just search your favorite bookstore.

        1. Harold

          By “Huns” do you mean Mongols? The disease is endemic to the grasslands of Mongolia and also the Western United States. Supposedly Genoese traders brought it to Constantinople from their ports in the Crimea, I thought.

          1. The Historian

            Yes, it is probably more correct to call them Mongols because that is who they were fighting under, although some of the midieval historians that I have been reading called them Tartars and Huns, based on what tribes they belonged to. And Caffa, the city where the plague probably got its foothold, was both in Crimea and a port on the Black Sea. And yes, it did strike Constantinople first but since the topic was Europe proper, I just stated that ships brought it to Italy.

    2. PlutoniumKun

      I’m not really convinced – for one thing I’d always understood that the Black Death did hit many other populations, they just weren’t recorded so well (I can stand corrected by this, I don’t know the latest research). It also doesn’t explain why so far the home countries of those ethnicities that have been hit so hard in the west – East Asians, Iranians, SE Asians, have so far not been hit so hard by Covid. Indians and Pakistani’s in particular seem to have been hit very hard in the UK, and yet the same can’t be said in their home countries. This is why I suspect that a mix of socio economic (there is evidence that non-white healthcare workers are more likely to be put on the frontline), plus dietary/vitamin D related explanations may be stronger.

      But its an interesting theory, nonetheless.

      1. Synoia

        East Asians, Iranians, SE Asians, have so far not been hit so hard by Covid. Indians and Pakistani’s in particular seem to have been hit very hard in the UK, and yet the same can’t be said in their home countries.

        Ambient Temperatures are very different, and there are some reports of less virulence in hotter climates.

        1. PlutoniumKun

          Iran and a large chunk of Pakistan is actually quite cold in winter and early Spring. Tehran temperatures only went above a max of 20C in the last 2 weeks or so. Much of the temperature range of that region is not all that different from the inland cities of northern Italy and Spain.

      2. HotFlash

        Indians and Pakistani’s in particular seem to have been hit very hard in the UK, and yet the same can’t be said in their home countries.

        I wonder, are there differenced betw first or second generation immigrants? Age groups? Another factor that seems to correlate is vaccination for tuberculosis. The BCG vaccine (which is the only tuberculosis vaccine, although there are several strains and manufacturers of it) is mandatory in a number of countries, including India and Pakistan. Some countries never did it, and others have ended or limited their TB vaccination programs as cases of TB diminished.

        Group 1: Italy, Belgium, the Netherlands, Canada and the US never universally vaccinated for TB.

        Group 2: The UK, Australia, New Zealand, Equador, and most of Europe discontinued universal vaccination of children in the late 20th C, reserving/requiring it only for ‘at risk’ children.

        Group 3: The BCG vaccine against tuberculosis is still mandatory in a number of countries, including China, India, and Pakistan, and it is mostly children who are vaccinated, typically in their first year. There may or may not be a booster, usu late pre-teen.

        There are lots of variables to work out — lockdown, distancing, age of population, co-morbidities, yada yada. But just doing a deeper dive into Spain is interesting. Universal vaccination program started in 1965 for all newborns, no booster, and stopped in 1981, except for at-risk children. So that is a cohort of approx 49 to 55 year olds vaccinated. It would be interesting to see if the mortality rate was different in that group. Bonus! Basque region children are automatically considered ‘at-risk’ and have been vaccinated up to present! We have a control group! Would love to see data on that.

        Here are the charts, people, go crazy. 91-divoc, this is deaths normalized for population, and the BCG World Atlas.

        Esp for Pu-kun, note that RoI and NI have different policies. Does this agree or not with your observations?

    3. Bsoder

      Too bad Evolution 101 or 202 is not taught in red states, just not how god does things.

    4. Science Officer Smirnoff

      Reply to Hayek’s Heelbiter
      May 7, 2020 at 11:17 am
      On remdesivir:
      The drug, made by the US company Gilead Sciences, is an antiviral that was trialled in Ebola, but which failed to show benefits in Africa.
      —The Guardian Thu 23 Apr 2020 15.35 EDT
      [emphasis added]

      1. Hayek's Heelbiter
        Nevertheless (emphasis mine)

        As an adenosine nucleotide triphosphate analog, the active metabolite of remdesivir interferes with the action of viral RNA-dependent RNA polymerase and evades proofreading by viral exoribonuclease…its predominant effect (as in Ebola) is to induce an irreversible chain termination. Unlike with many other chain terminators, this is not mediated by preventing addition of the immediately subsequent nucleotide, but is instead delayed, occurring after five additional bases have been added to the growing RNA chain.[56] Hence remdesivir is classified as a delayed chain terminator.

        [56] Tchesnokov EP, Feng JY, Porter DP, Götte M (April 2019). “Mechanism of Inhibition of Ebola Virus RNA-Dependent RNA Polymerase by Remdesivir”. Viruses. 11 (4): 326. doi:10.3390/v11040326. PMC 6520719. PMID 30987343.

    1. Hayek's Heelbiter

      I was trained as a scientist, and can’t remember where I read the article. But it pointed out a rather obvious truth, that scientists and epidemiologists study phenomena RETROSPECTIVELY. Risk assessors (a job description that I had never before heard) study things PROJECTIVELY.

      You can see the difference in the stats of the devastation of the countries who awaited the consensus of the scientists before acting versus the lesser disruption of countries who heeded the warnings their risk assessors (familiar with SARS and MERS and responses thereof) and almost immediately imposed lockdowns and other protocols.

  6. Cuibono

    My questions

    1 how important is asymptomatic transmission?

    2 what is the relative importance of different locales of transmission

    3 does prior SARS infection provide protection

    1. Ignacio

      Your first two questions are unfortunately very difficult to address.

      I think asymptomatic or nearly asymptomatic direct transmission is very important when there is not awareness of disease in the community. Then, there is fomites-led transmission which is even more elusive than asymptomatic direct transmission. So, when you detect someone with symptoms in a community if then everyone is tested it is almost certain some more will show positive. A couple of days later some many more will. So when first symptoms appear everyone must be isolated from each other, clean all surfaces, masks mandatory, and if the community includes some medical and other care full protection by and for the providers. Suddenly the community transforms into something resembling a military camp in wartime.

      What i find most difficult is to decide what discipline to keep BEFORE the first case appears.

  7. John k

    Everybody’s different, flu only kills a very small fraction, granted elderly get shots. Maybe some differences are nutritional.
    My thought is that there is a wide variety of vitamin d and zinc levels in those that get the virus, and that low levels worsen the outcome. And maybe nicotine also provides protection.
    Diets low in red meat and oysters typically mean low zinc, plus local soils may be low, too… I saw an indication North American soils are generally low. Poor people on cheap diets likely get little red meat. Hiding inside means low vit d, plus many seniors like me anyway seek shade to avoid harmful rays. And most living seniors stopped smoking, so no nicotine input.
    I take vit d, plus zinc in a multi, have zinc lozenges on hand if I get symptoms, and if they worsen would add nicotine patch.

    1. Bsoder

      American soils remain the richest in the world. Zinc would be a mineral and mined. There’s no evidence based data to indicate for people in general zinc going to do anything. But if makes you happy sure why not. I’d ask my doc for a blood test on minerals and a vitamin panel. Then you’d know.

        1. rd

          It is a function of regional geology. The northern US and Canada were largely glaciated and the soils are very recent (<100,000 years old) and so have not leached their nutrients and miinerals out. The rolling farmed plains of Western NY, OH, IL, KS, NE, etc. are glacial till plains or old glacial lakebeds. The Russian steppes are similar. Much of the major floodplains come from such soils and are rich as well (e.g. Mississippi).

          Much of the South and California are old soils that are classified as "residual", basically bedrock weathered in place with a lot of leaching over hundreds of thousands or millions of years. These regions often have limited crops that can be grown or require a lot of fertilizer and maintenance. The same issues hold true for much ot the tropics (the reason why the Amazon rainforest has slash and burn agriculture to open up new areas that are temporarily rich.

          1. Yves Smith Post author

            This is not correct.

            The Department of Agriculture was recommending in the late 1930s that Americans take vitamins because the soil was too depleted for consumers to get enough nutrients from a standard diet.

            The Department of Agriculture lists 74% of US land as degraded in a 2001 study. It has to be worse now:



            AMERICA USED TO be famed for its rich and fertile topsoil. Prairie and forests were virtually untouched when settlers first started dividing land into fields across the Southeast and Midwest, making for rich dark soil in which to grow food and fiber.

            Since the invention of the plow, farming has focused on disrupting the soil to make it productive. Most farming methods, whether conventional or organic, are based on “tillage” – the premise that to plant crops and control weeds and other pests, the soil must be broken up and turned over, then amended with chemical fertilizers or organic compost to boost fertility. And it worked for a long time.

            But tilling, it turns out, kills off many of the microorganisms that build the soil. It churns up their habitat and exposes them to air; it also makes it easier for soil to be washed off the land by rain and wind. Over time, the damage has built up: More than 50 percent America’s topsoil has eroded away. In areas of the Southeast, the country’s original breadbasket, it’s almost all gone…

            Promoting soil health comes down to three basic practices: Make sure the soil is covered with plants at all times, diversify what it grows and don’t disrupt it. What this means in practice is rotating crops, so fields aren’t trying to support the same plant year after year. And it means using techniques like “cover-cropping”–planting a secondary plant like grasses, legumes or vegetables–between rows of crops or on other exposed soil instead of leaving it bare. Using a cover crop protects the soil, reduces erosion, encourages biodiversity and returns nutrients like nitrogen to the earth.

            For the most part, agriculture isn’t very good at doing any of these things.


  8. Bob

    Regarding why are some countries not experiencing as much COVID-19 as the U.S., Europe and China, my personal non-scientifcally vetted opinion is that this this virus spreads indoors. Fresh air, ozone and UV radiation are all natural disinfectants. Outdoors, coughs and sneezes are dispersed via the wind.

    This could also explain why the disease is concentrated in urban settings like NYC, present in warm weather locations like Singapore and implies it won’t necessarily go away come the summer. On the other hand, the poorest citizens in the poorest countries spend a lot of time outdoors and don’t seem to be as hard hit. Though this has been attributed to a lack of testing, their homes aren’t hermetically sealed and climate controlled like those in the US, Europe or China which I believe leads to a lower infection rate. That being said, people who live in urban slums are certainly vulnerable.

    1. Moshe Braner

      There is also the issue, recently somewhat in the news, of different genetic variants of the virus. I’ve heard the claim that that explains why NY has been hit harder than the US West Coast – that the variant in NY supposedly came from Italy, while the West Coast got it from China. Of course they also spend more time outdoors on the West Coast than in NY, especially in February.

      1. Anonymous2

        Yes. Reportedly there has been a mutation (the G Clade) which has resulted in a virus which is more contagious. This is the strain which is thought to be active in Europe.

  9. WhoaMolly

    I wonder if air conditioning systems could be contributing to infections by recirculating the air inside buildings.

    My reasoning:
    – Air conditioning systems in commercial buildings recirculate the existing air, without adding much new outside air.
    – The virus may ‘ride’ air pollution particles.
    – Commercial air conditioning systems don’t have filters designed to remove viruses.

    1. rd

      Commercial real estate is probably going to have to increase their fresh air exchange and potentially install electrostatic filters if they don’t have them. Without that, offices are likely to be unhealthy.

      1. neo-realist

        Offices have been unhealthy, air wise, for years. We just cough, hack, adapt, deal.

        1. JTMcPhee

          In the late ‘70s the former US EPA headquarters was finally identified as a “sick building” in a distressing bit of irony. Crappy air conditioning, paints and carpets and carpet adhesives that emitted formaldehyde and a nasty brew of toxic and carcinogenic chemicals, molds, you name it and it was a toxicologist’s delight.

          Here’s the administrative bandaid applied, after years of complaints by staffers:

          Some fact sheet stuff on sick building syndrome:

          Interesting how little one hears about this issue any more, or maybe it’s just that my horizons have shrunk.

    2. dk

      The short answer is yes.
      The term for the motile form of a virus is virion, one or more strands for RNA (of DNA but SARS-CoV-19 is RNA) enclosed in a fatty lipid capsule (“capsid”), usually with protruding receptors with which the virion can attach to and inject it RNA strand into a host cell. Coronaviruses have characteristically prominent “spikes,” receptors that extend beyond the capsid surface.

      Basically, virions are little blobs of fat. When exposed directly to air they quickly rancidify and the exposed RNA strand disintegrates. Riding air pollution particles is possible but unlikely, as many of these kinds of particles have surfaces antagonistic to the fatty capsid. However, exhaled particulate droplets suspended in air can pass through coarse filtration. HEPA filters are designed to trap such droplets, UV irradiation can “cook” them.

      Here is a study on an early transmission site in China, where incidents of infection seem to correlate to ventilated air flow in a restaurant:
      COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020
      The Figure 1 illustration helps to visualize this:

      Here is a not-yet-reviewed preprint of a study of two buses transporting attendees to and from an event in China. One bus (#2) had a suspected “index patient” (IP), the other didn’t.
      From the article: “In both buses and conference rooms, central air-conditioners were in indoor re-circulation mode.”

      Interestingly, the conference itself produced few further cases, these were all traced to prolonged interactions with the IP. Generally with viruses, some critical mass of virions must accumulate in sufficient number to produce infection, and total net exposure may approximately correlate with severity. Untreated recirculated air bearing virus-laden droplets may lead to repeated exposure and increase concentration of virions in individuals.

      1. juliania

        “… many of these kinds of particles have surfaces antagonistic to the fatty capsid. However, exhaled particulate droplets suspended in air can pass through coarse filtration. HEPA filters are designed to trap such droplets, UV irradiation can “cook” them…”

        Thank you for this, dk. I would remind us all that years ago it was touted for the care of infants to bathe them with antibacterial soaps. Then suddenly, it was realized that this removed the infant’s protective bacterial layer that was a layer of good germs, not bad ones, as would be present in most households that don’t do a huge amount of ‘sanitizing’. There are more good germs we normally are exposed to than bad ones – even with virulent ones in the mix.

        Early descriptions of what was occurring in the extreme cases have posited that the victim’s own immune system seemed to be going haywire. If that is still thought to be happening, my question would be one directed at ‘flu shots, which as has been noted, the aged often get quite religiously every year. My question would be, does such practise inordinately stress the immune system? Are there any studies, as for instance in nursing homes, looking at these vaccinations vs. the persons who do not get the shots? I realize this is a pro-vaccination vs. anti question and I don’t want to raise it about vaccinations in general. But maybe for corona viruses and their ability to adapt, the question is worth asking. If we don’t want to eliminate all bacteria from the skin of an infant, maybe some caution ought to be observed in eliminating other teeny invaders as well.

        1. dk

          I agree, holistic effects should be a concern. “First, do no harm.” is often given as an abbreviated maxim of the Hippocratic oath*.

          There haven’t been enough well focused studies to give definitive answers to the concerns you raise. Vaccination is still a developing technology in the modern setting; this is true of medical science in general. As ever, we rely primarily on the collected experience and good faith efforts of practicing medical professionals.

          This EU institution-funded paper from 2017, “Immune responses after live attenuated influenza vaccination,” reviews statistics and studies (given in references) is the closest discussion to your questions I found, considering age differences and the two predominant approaches to vaccine, inactive virus and live attenuated virus:

          This table from the paper, compiled from a further paper not found, summarizes the comparisons (and may be subjectively different from the assessment of studies sponsored more directly by the pharma industry):.

          Table 1. A comparison of the immune responses after natural infection, and immunisation with inactivated influenza vaccine (IIV) or live attenuated influenza vaccine (LAIV).

          Immune response          | Natural infection |   IIV   |  LAIV
          Serum Ab response (HI)   |        ++         |   +++   |   +
          Antibody secreting cells |        ++         |   ++    |   +
          Memory B cells           |        ++         |   +     |   ++
          Nasal IgA                |        ++         |   -/+   |   +++
          CD4 T-cells              |        ++         |   ++    |   +++
          CD8 T-cells              |        ++         |   -     |   +
          Cross protective immunity|        +++        |   -/+   |   ++

          Clearly, general long-term cross protective immunity gets highest marks on from survived natural infection. It is already clear that SARS-CoV-19 raises the mortality ante on influenza viruses, but culturally, especially in the US, we do not practice nearly as much preventive behavior as we might. My own very strong opinion is that preventive and aggressive preemptive tactics are both more readily available and also more broadly affordable (sometimes even free, and reducing conventional expenses). As well, the most basic methods have been well tested and explored by our species over thousands of years.

          *The full Hippocratic Oath is more elaborate; the most directly relevant of the common modern Oath is:

          I will apply, for the benefit of the sick, all measures [that] are required, avoiding those twin traps of overtreatment and therapeutic nihilism.

          This Wikipedia article discusses Oath and axiom at greater length:“First_do_no_harm”

          Another noteworthy phrase from the modern Oath, emphasis mine:

          I will prevent disease whenever I can, for prevention is preferable to cure.

    3. ObjectiveFunction

      Been musing a bit about HVAC myself. While I’m not a facilities guy, I have spent a fair amount of time working around clean rooms of various classes in GMP biopharma and semiconductors.

      Might some of the same principles be feasible (over time) in spaces where people simply must congregate, such as hi rise elevators, aircraft or rail cars?

      In a clean room, a negative downward air pressure is maintained in the entire space, with ceiling units pushing air in, such that any airborne contaminants are rapidly precipitated down through a porous (waffle) floor, and thence evacuated to filtration. There is a distinct and steady downward ‘breeze.’ All apertures are sealed (plastic curtains can be used as stopgaps for doors).

      Cleanroom workers also gown in bunny suits to prevent entry of contaminants on clothing. But for merely preventing infection, say, a beekeeper type hat including a clear plastic cover falling to the shoulders, left open at the bottom for ventilation (except in a confined space) might suffice, as chances of sneeze droplets rising into it are greatly reduced. Room for experimentation here, and a lot nicer than wearing a P95 mask all day (people will cheat).

      … Not saying any of that is easy though, or cheap. Retrofitting: replacing the ceiling and lights, lifting the floor and sealing the envelope are no small matter. New ducts strung up everywhere, like in the film “Brazil”. You also have hugely increased energy consumption, so it’s unlikely this would find its way into a typical cube farm. And no, this won’t mitigate risk of transmission via touch; as Gov Ratface says, some safeguards can only be personal.

      I don’t see much on this on the Web yet, which may mean it’s just a dumb idea. However, there looks to be a boomlet in helping hospitals fit Covid rooms, both via mobile units or modular rooms.

      Any Facilities pros here to ‘splain to me why this is the dumbest idea ever? I’m not a proud man….

    4. Displaced Platitudes

      In older buildings, this may apply.
      In newer buildings, ASHRAE IAQ standards require 15 CFM or greater of outdoor air. ASHRAE standards effectively tripled the amount of outdoor air required for spaces.This outdoor air is usually run through an air-to-air heat exchanger to avoid excessive energy costs. Prior to the heat exchanger a bank of air filters, usually MERV 8 or better, remove dust and larger spores. In some cases, prior to the the bank of filters an additional bank of MERV 8 media filters are installed. Prior to the heating/cooling coils and after the 2 banks of filters, a MERV 11, or greater, bank of filters removes all remaining dust and much of any airborne droplets. This bank of filters also repeats filtration for return air from the spaces with an additional bank of MERV 8 filters on the return air.
      All this filtration helps a great deal, but even HEPA filters will not remove all airborne particles. Possible improvements might involve UV filtration that would be quite expensive. I’m not aware of any hospitals that have UV filtration for anything except ICU and lab spaces. Electrostatic filtering would require an even more expensive refitting of air handlers to meet the ASHRAE standards.
      All this said, It’s certainly possible that viruses could spread through HVAC systems. It’s even exceedingly likely that they could spread through a residential forced air system. Individual HEPA units in a home are unlikely to filter enough air thoroughly to avoid the problem entirely.
      At the point that mankind decided to reach for the clouds, we set up the environments to make sure we would bring our illnesses with us.

  10. RJ McElroy, MD

    The number of impressive ideas from many sources in the comments indicates that in spite of an estimated 5,000 papers (reports, studies, etc) the COVID-19 infection poses many more questions than for which we have answers. Much of this material has to do with either the epidemiology of the infection or understanding and dealing with the pulmonary manifestations. The initial focus in dealing with the infection has been a pulmonary infection that may range from asymptomatic to requiring a ventilator because of hypoxia complicated by a “cytokine storm” and or a major coagulation disorder or coagulopathy.

    The vascular endothelium and endothelial cell may be a major part of pathophysiology of the COVID-19 infection. The endothelium lines all parts of the vascular system: all arteries down to the capillaries, veins and is the lining of the heart.These cells are generously endowed with ACE2 receptors according to a study published in the Journal of Pathology in 2004. The endothelium and coagulation factors in the blood are intimately related. At least one study published in the Lancet Correspondence April 20, 2020 suggested the virus was “killing” endothelial cells as studies by electron microscopy. Disruption of the endothelium in other situations can trigger clotting. The lung pathology in some patients has shown extensive in situ clotting of arteries down to the capillaries and this may at least on occasion be the cause of death as apposed to damaged lung cells. The protean manifestations of COVID-19 infections from being asymptomatic to extensive lung destruction, “cytokine storms”, coagulopathy, COVID toes particularly in children, strokes, coronaries, kidney failure and a Kawasaki like syndrome in 25 young children makes understanding this pandemic a complicated problem.

Comments are closed.