This article was published on medium.com website and circulated among some fellow members of the Canadian Club of Rome in mid-March, 2020. As I had been watching the evolution of the coronavirus pandemic that started in late 2019, I had been wondering about the routes of transmission of the SARS-CoV-2 (SARS2) virus that causes the disease. On reading the article, I was immediately struck that the author is likely making a recommendation that, while well-intentioned, could be counter-productive in that it would provide a false sense of security and divert resources from efforts that actually will contain the virus, perhaps even be counter-productive.
What I record here is simply my opinion about the article. I will begin with the author’s conclusions, then examine his credentials, his evidence, and his rationale. However, there’s a critical item to stress first: SARS2 causes grave damage to the lungs and it is inhalation deep into the lungs that we need to focus on preventing until such time as we have a vaccine and/or medication to treat the coronavirus disease (CoViD-19). The masks we now have will not do that, as will be apparent in the discussion below.
Limitations: I had no co-authors and no peer reviewers. Why? The reason is that I prepared this for the edification of a very small (<100) group of colleagues whom I felt it was important to inform as quickly as possible, for among them may be influential people and people vulnerable to this
There is, I trust, what you’ll find to be a high level of detail.
The Author’s Conclusions
The author says: “…the major transmission mechanism is not via the fine aerosols but large droplets, and thus, warrant the wearing of surgical masks by everyone.” Unfortunately, he provides no evidence. For example, he does not reveal the proportion of infections that result from direct contact (or any other possible route of transmission). That is because it remains unknown.
The author does not discuss the elephant in the room, however: assuming every person would require even just two masks per day and would launder the masks once each week, within a week or two we would need:
7.8 billion people x 7 days/laundry load x 2 masks/d = ~110 billion masks
Cost aside, we would have to convert thousands of factories to producing these masks, complete with all the machinery, raw materials, and wastes that would involve. There would have to be a great deal of masks replacement and waste management. The logistics of distribution would be
horrendous—we can’t even get food to everyone now.
Essentially, we would be looking at adding an ocean of masks to the ocean of plastics we recently created . Now, imagine if the masks mostly get tossed rather than laundered.
Education: Dr. Huang styles himself as a molecular and cell biologist, with a strong background in theoretical biology, who has specialized in cancer research, gene regulatory networks, and the theory of complex systems. He was educated in Zurich. His doctorate was in Molecular Biology and
Work: He has been at the Institute for Systems Biology in Seattle, WA, USA, since 2011. Previously, dates unknown, he held faculty positions at the Institute of Biocomplexity and Informatics (University of Calgary, AB) and at the Children’s Hospital (Harvard Medical School, MA, USA).
Publications: He has published 58 articles in the following journals (by year, lead authorship on 18 papers is marked by asterisks, sole authorship on 13). None of the papers pertained to viruses, virology, infection, infectivity, personal protective equipment, air flow, flow dynamics, or anything similar, though it is possible some aspects of such topics could have been covered in some of the papers insofar as some viruses do cause cancer.
2004: Nat Biotechnol
2006: Breast Disease *; Reviews of Physiology, Biochemistry and Pharmacology *
2007: Developmental Biology *; Annals of the New York Academy of Sciences; PLoS
Computational Biology; International Journal of Modern Physics
2008: PNAS USA; Nature; PloS One; Journal of Computational Biology; PPAR Research
2009: Circulation—Cardiovascular Genetics; Nature Reviews—Genetics; BioEssays *;
Seminars in Cell & Developmental Biology *; J Theoretical Biology; Development *
2010: Nature Chemical Biology; PLOS Biol *; Biophysical Journal; Cancer and Metastasis
Reviews; Nature Reviews—Genetics
2011: Trends in Genetics; Experimental Biology and Medicine; Semin Cancer Biol *;
Philosophical Transactions of the Royal Society of London—Series B, Biological Sciences *;
Prostaglandins & Other Lipid Mediators, Eicosanoids and disease; PloS One; PloS One
2012: J Clin Invest; BioEssays *; Stem Cell Res; Progress in Biophysics and Molecular Biology
*; J Cereb Blood Flow Metab; Journal of the Royal Society (Interface); BMC Bioinformatics;
PLoS Comput Biol
2013: BioEssays *; Nat Methods; PNAS USA; PLoS Biol *; Semin Cancer Biol *; Cancer
Metastasis Rev *; Nat Commun
2014: Bioessays *; European Journal of Immunology; Frontiers in Oncology *; Nucleic Acids
Research; Frontiers in Oncology; PloS One
2015: Br J Cancer; PLoS One; Scientific American Worldview
2016: Oncotarget; PNAS USA; PLoS Biology *; Bio Systems
It is interesting that he wrote one paper entitle “When Correlation and Causation Coincide.”
In summary, the author appears to be a bona fide scientist, though he has very limited expertise with viral epidemics and viral transmission. It is disappointing to me that he didn’t apply the rigour to the article that must have gone into his publications in journal such as Nature.
The article presents no data obtained by the author from observation or experimentation. Rather, it relies on information from other scientists.
The article is difficult to navigate because there is no list of citations, but if one hovers over and clicks on each reference, the original paper opens on the internet.
I was not able to open the link for Figure 1 (404 error for page not found). Thus, I do not know whether the author produced the graph himself. It is essentially the same as the ‘flatten the curve’ graph that has been widely circulated. The point of the figure is to show that, in USA, controls might reduce the peak of simultaneous infections from 57 million to 32 million. Oddly, without controls 40% to 70% of people in USA will get the disease (which is ~130 to 230 million cases) and the figure does not give total infections, though the area under the curve up to day 100 (after the first 100 cases) likely represents that and might be the same. Worse yet, there is not yet any way to know how much the case load can be reduced or how fast, so essentially the figure is of little or no use.
There is no source for Figure 2, though there are links in the caption to:
- Relative Contributions of Four Exposure Pathways to Influenza Infection Risk. M Nicas and
RM Jones. 17 August 2009. https://doi.org/10.1111/j.1539-6924.2009.01253.x.
- How far droplets can move in indoor environments—revisiting the Wells evaporation–
falling curve. X Xie, Y Li, ATY Chwang, PL Ho, and WH Seto. 29 May 2007.
Figure 2 purports to show that large droplets from coughing go up to 2 metres, while such droplets from sneezing go up to 6 metres. Science a decade ago pegged the large droplets as subject to a great deal of drag and unable to go further than about 1 metre, finer droplets up to 2 metres, but let’s accept this larger travel distance. The figure shows aerosols particles floating outside the spray zone. In fact, the aerosols will go much further than the droplets and represent around half the probably viral load (more on this later). So, really, the figure doesn’t deal with what could be a
major transmission route.
There is no source for Figure 3, though there is a citation just prior to that figure:
- Toward Understanding the Risk of Secondary Airborne Infection: Emission of Respirable
Pathogens. M Nicas, W W Nazaroff, and A Hubbard. Pages 143-154. 17 Aug 2010.
Figure 3 says that droplets go further than 2 metres and does not mention a travel distance for aerosols. It does show aerosols as going deep into the lungs, saying they are only effectively blocked by N95 masks. It does not mention that deep inhalation is thought to lead to the most severe disease, nor that N95 masks do not filter out particles less than 0.3 microns in size, while the virions are 0.6 to 0.14 microns. It is those tiny virions that form droplet nuclei and which likely present a major risk.
There is no source for Figure 4 (which simply shows a set of 3 photographs of people wearing different types of masks), though there is a citation just prior to that figure:
- Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population. M van der Sande, P Teunis, and R Sabel. July 9, 2008. https://doi.org/10.1371/journal.pone.0002618.
There is no source for Figure 5, though the text gives the impression the author drew it from information present in van der Sande et al., 2008. This figure deals with the aerosols that were mostly ignored in previous figures. It shows many particles get through all masks on exhalation via coughing and some particles getting through even N95 masks on simple inhalation. The study did not deal with particles less then 0.2 microns in size, so the figure does not deal with the virions that may represent a major risk. It does not mention anything about leakage from the sides of masks when coughing or sneezing occurs, nor anything about escape of captured virus particles when the masks are handled.
There is no source for Figure 6, which shows the stylized structural diagram of the virus. It is a minor point that the outer covering of the virus is actually a lipoprotein layer that originates from the host cell’s outer membrane—the viral RNA does not encode for its production. It is also a minor point that the RNA is contained in a protein capsid that gets injected into the cell and from which the RNA emerges. So, the figure has a few flaws.
Without a normally formatted citation, there is a link to a recent paper published in an unknown source:
- SARS-CoV-2 Entry Genes Are Most Highly Expressed in Nasal Goblet and Ciliated Cells
within Human Airways. W Sungnak, N Huang, C Bécavin, and M Berg (Hunan Cell Atlas Lung
Biological Network). https://arxiv.org/ftp/arxiv/papers/2003/2003.06122.pdf.
There is no source for Figure 7, which is essentially Figure 3 redrawn to show that the virus may enter cells in the nose first. There is no mention of how the virus might get from the nose into the lungs to cause severe damage in the alveoli, which is what causes eventual death in about 3% of patients—there is a passage concerning this following Figure 3, with a citation from the CDC.
- Guideline for isolation precautions in hospitals Part II. Recommendations for isolation
precautions in hospitals. The Hospital Infection Control Practices Advisory Committee, CDC.
Public Health Service, US DHS. Am J Infection Control. https://doi.org/10.1016/S0196-
That passage even mentions that damage to the alveoli has led some to believe masks are rendered useless by it. It is followed by a paragraph on how the virus appears to replicate in the upper respiratory tract, from which it could be ejected and spread. However, one is still left wondering about the route to the lower lung.
Just after Figure 7 is a citation of:
- Clinical presentation and virological assessment of hospitalized cases of coronavirus disease 2019 in a travel-associated transmission cluster. R Woelfel, VM Corman, W Guggemos, M Seilmaier, S Zange, MA Mueller, D Niemeyer, P Vollmar, C Rothe, M Hoelscher, T Bleicker, S Bruenink, J Schneider, R Ehmann, K Zwirglmaier, C Drosten, and CWendtner. https://doi.org/10.1101/2020.03.05.20030502.
There are several other links to statements, definitions, and guidance document that are not
formatted as citations:
- Tweet from the US Surgeon General: Seriously people–STOP BUYING MASKS! They are
NOT effective in preventing general public from catching #Coronavirus, but if healthcare
providers can’t get them to care for sick patients, it puts them and our communities at
- Understanding the Difference—Surgical Mask [and] N95 Respirator.
- Why Telling People They Don’t Need Masks Backfired: To help manage the shortage, the
authorities sent a message that made them untrustworthy. Zeynep Tufekci, professor of
information science who specializes in the social effects of technology. New York Times
Opinion Letter. https://www.nytimes.com/2020/03/17/opinion/coronavirus-facemasks.
- Rational use of face masks in the COVID-19 pandemic. S Feng, C Shen, N Xia, W Song, M Fan,
and BJ Cowling. March 20, 2020. https://doi.org/10.1016/S2213-2600(20)30134-X.
- Infection Trajectory: See Which Countries are Flattening Their COVID-19 Curve[s].
N Routley. Visual Capitalist, opinion article. March 16, 2020.
- A New York Times article that appears to be about the low cost ($0.75 ea.) of certain masks
and which requires a login [which I won’t do at present].
- A New York Times article that appears to be about flattening the curve.
N95 Respirators and Surgical Masks. L Brosseau and RB Ann. NIOSH Science Blog. CDC.
October 14, 2009.
- A functioning link to the item listed earlier that had a 404 error, which is a website where
one can input parameters and generate a graph of an epidemic.
- Respiratory Infection Control: Respirators Versus Surgical Masks. Fact Sheet. Occupational
Safety and Health Administration. https://www.osha.gov/Publications/respirators-vssurgicalmasks-
- The emerging role of ACE2 in physiology and disease. I Hamming , ME Cooper, BL
Haagmans, NM Hooper, R Korstanje, ADME Osterhaus, W Timens, AJ Turner, G Navis, and
H van Goor. 26 April 2007. J Pathology. https://doi.org/10.1002/path.2162
- The insert sequence in SARS-CoV-2 enhances spike protein cleavage by TMPRSS. T Meng, H
Cao, H Zhang, Z Kang, D Xu, H Gong, J Wang, Z Li, X Cui, H Xu, H Wei, X Pan, R Zhu, J Xiao,
W Zhou, L Cheng, and J Liu. https://doi.org/10.1101/2020.02.08.926006.
- ACE2 and HYPERTENSION. March 14, 2020. http://www.nephjc.com/news/covidace2.
- Mechanical Stress and the Induction of Lung Fibrosis via the Midkine Signaling Pathway.
R Zhang, Y Pan, V Fanelli, S Wu, AA Luo, D Islam, B Han, P Mao, M Ghazarian, W Zeng,
PM Spieth, D Wang, J Khang, H Mo, X Liu, S Uhlig, M Liu, J Laffey, AS Slutsky, Y Li, and
H Zhang. May 01, 2015. Am J Respiratory and Critical Care Medicine.
- Q: I am having trouble obtaining viral transport media/universal transport media
(VTM/UTM) and a flocked nasopharyngeal swab to collect and transport patient samples.
Are there alternatives that I can use? https://www.fda.gov/medical-devices/emergencysituations-
2#trouble obtaining viral transport.
- Loss of sense of smell as marker of COVID-19 infection. C Hopkins and N Kumar. ENT UK
at The Royal College of Surgeons of England.
- Coronavirus Disease 2019 (COVID-19): Facemasks.
Suffice to say, it is sometimes difficult to tell where the author’s opinions are and where information from other scientists appears. Among the 24 sources, there appear to be 12 journal articles, 7 fact sheets and technical notes, 4 opinions pieces, and 1 tweet.
For a topic so important—whether masks can be useful in this pandemic—surely it should have been important to do a more in-depth examination of the literature. There are dozens of new articles on SARS2 and likely dozens more about protective equipment and masks in particular. Here is an example of a recent (2017) paper he did not use. It was a meta-study of about 30 research papers.
- Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare
Workers: A Systematic Review and Meta-Analysis. V Offeddu, CF Yung, MSF Low, CC Tam.
Clinical Infectious Diseases. 1 December 2017. https://doi.org/10.1093/cid/cix681
Here is most of the abstract from that paper, my emphasis added in bold.
- Meta-analysis of randomized controlled trials (RCTs) indicated a protective effect of masks and respirators against clinical respiratory illness (CRI) (risk ratio [RR] = 0.59; 95% confidence interval [CI]:0.46–0.77) and influenza-like illness (ILI) (RR = 0.34; 95% CI:0.14–0.82). Compared to masks, N95 respirators conferred superior protection against CRI (RR = 0.47; 95% CI: 0.36–0.62) and laboratory-confirmed bacterial (RR = 0.46; 95% CI: 0.34–0.62), but not viral infections or ILI. Meta-analysis of observational studies provided evidence of a protective effect of masks (OR = 0.13; 95% CI: 0.03–0.62) and respirators (OR = 0.12; 95% CI: 0.06–0.26) against severe acute respiratory syndrome (SARS). This
systematic review and meta-analysis supports the use of respiratory protection. However, the existing evidence is sparse and findings are inconsistent within and across studies. Multicentre RCTs with standardized protocols conducted outside epidemic periods would help to clarify the circumstances under which the use of masks or respirators is most warranted.
So, that study showed some protection being provided, but, while the authors said use of respiratory protection appears advised for healthcare workers, they hardly seemed ready to endorse widespread use of masks by the public. It is quite a good study I suggest everyone should read.
As to the information presented, these are his main points, plus my comments about each.
1. Using a mask of any type may be an imperfect barrier to viral transmission, but it might help prevent infection, so we should give everyone masks. This is speculation, not evidence based practice.
2. The ballistics of droplets from sneezing and coughing through the nose and/or mouth are such that if a barrier is placed in front of the openings, droplets will be trapped and transmission of the virus to another person interrupted. We know people are getting infected by being in rooms with asymptomatic carriers of the virus and while wearing masks.
3. It is the large droplets that need to be captured. We know the large droplets fall out of the air within seconds and that at least half of the viral load exhaled is in the fine mist that remains in the air for hours to days.
4. Relying on “intuition” allows the conclusion that some attenuation of droplet spread is better than no attenuation. We need to focus our efforts on procedures and equipment that can scientifically be shown to be effective—anything else is a waste.
5. We do not have good evidence that staying 2 m away from each and hand washing are effective at preventing viral transmission, so we should use a different methods (masks) for which we also have no good evidence. We should not be using any measures for which we have no evidence of effectiveness. As it happens, there are studies on the effectiveness of social distancing and hand-washing. The former clearly works; the latter is suspect if simply because it may be that people with clean hands still get infected by inhalation of aerosols that even N95 masks do not filter—at present we are relying (unsatisfactorily) on previous experience with infection control, largely for bacteria, fungi, and parasites.
6. We don’t know to what proportion of transmission is via large spray droplets as opposed to aerosols or how much social distancing alone contributes to reducing transmission, but we should still give everyone masks. There are many measures we could use that are likely to work even better than giving people masks and there is no reason to move to masks without evidence they work adequately—not just a little, but adequately to prevent infection.
7. The ACE2 receptor for SARS2 may be even more frequent in mucosal cells in the nose than in the lungs, so we should be concerned about droplets getting into the nose and causing infection. The damage SARS2 causes is in the lungs and the symptoms in the nose are mild to absent. There is not even a hypothesized mechanism for the virus to get from the nose to the lungs.
8. We are now finding SARS2 in the nose, so we should be concerned about it getting in and out of the nose, which could be prevented by masks. Were this simply a nasal infection, it would be so deadly and we would not be spending much effort fighting it.
9. Surgical or self-made masks, if handled properly, will at worst not hurt and may at best, help. Actually, we have evidence that handling of masks while they are being worn and when they are being removed can result in spreading the influenza virus and people getting infected, which should give us pause. Tacitly, the author acknowledges this point by saying the outer surface of a mask should not touched.
10. “It would be tragic if the wrong logics and mechanics and biology, which has led Western governments to not encourage, if not stigmatize the wearing of masks, may have contributed to the steep rise of COVID-19.” It would be just as tragic if we gave everyone masks and it did little or nothing to lessen infection—it would only give a (bad) reason for blaming victims for their illness.
11. “There is now a robust scientific basis for putting an end to the officials’ anti-surgical mask hysteria and to recommend or even mandate a broad use of masks as in Asian countries that have bent the curve.” In fact, there may be such evidence, but it is not in this article. There is not even evidence here that masks bent the curve in Asian countries.
The Rationale Itself
The article is really an opinion piece, but it is scientific in two senses: it was done by a well-qualified researcher, though with no experience in the field of study; select published scientific papers and less formal publications from organizations that employ scientists were used for information. However, there was no original data and no examination of contrary evidence. The reader has no idea of how extensive the search for relevant information was. There was assessment of weaknesses in the argument or its sensitivity to error.
The author had no co-authors with whom to discuss his ideas.
There was no peer review of the work.
The degree to which the article is evidence-based is quite variable. For example, the author states near the outset that “N95 respirator masks…must be perfectly fitted and only professionals can do it.” There is no citation for that statement, and I can tell you from personal experience and training that it is patently false. Yes, a respirator needs to be closely fitted to the face—and taped onto the skin—but the fit can easily be checked by a co-worker.
Again, without citation or data, the author says “[statements by health officials about the public not needing masks] may have had unintended consequences: stigmatizing those that [sic] wear masks in the public (you are a hoarder, or you are contagious!).”
Again, without citation or data, the author implies “wear[ing] masks in Asian countries [worked as they] have now “flattened the curve” or even have had a flatter curve from the beginning. There is no discussion of all the measures that were taken in the various Asian countries and what, if any, effect each had on reducing transmission so as to flatten the curve of cases or of death. Indeed, there is little evidence that particular measures have discernible effects. I read one study (see next paragraph) where they examined the Number Needed to Treat (NNT) for various personal protective equipment against SARS found that adding all measures together (masks, face shields, gowns, gloves, personal hand hygiene) were no better than the best individual measure (NNT = 3), which means the PPE is not effective at preventing transmission. This directly explains how healthcare providers are getting sick, especially with SARS and SARS2 (COVID19).
Here is the abstract of that paper, my emphasis added: Of 2300 titles scanned 138 full papers were retrieve, including 49 papers of 51 studies. Study quality was poor for the three randomised controlled trials and most of the cluster randomised controlled trials; the observational studies were of mixed quality. Heterogeneity precluded meta-analysis of most data except that from six case-control studies. The highest quality cluster randomised trials suggest that the spread of respiratory viruses into the community can be prevented by intervening with hygienic measures aimed at younger children. Meta-analysis of six case-control studies suggests that physical measures are highly effective in preventing the spread of SARS*: handwashing more than 10 times daily (odds ratio 0.45, 95% confidence interval 0.36 to 0.57; number needed to treat=4, 95% confidence interval 3.65 to 5.52); wearing masks (0.32, 0.25 to 0.40; NNT=6, 4.54 to 8.03); wearing N95 masks (0.09, 0.03 to 0.30; NNT=3, 2.37 to 4.06); wearing gloves (0.43, 0.29 to 0.65; NNT=5, 4.15 to 15.41); wearing gowns (0.23, 0.14 to 0.37; NNT=5, 3.37 to 7.12); and handwashing, masks, gloves, and gowns combined (0.09, 0.02 to 0.35; NNT=3, 2.66 to 4.97). The incremental effect of adding virucidals or antiseptics to normal handwashing to decrease the spread of respiratory disease remains uncertain. The lack of proper evaluation of global measures such as screening at entry ports and social distancing prevent firm conclusions being drawn.
- Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review. T Jefferson, R Foxlee, C Del Mar, L Dooley, E Ferroni, B Hewak, A Prabhala, S Nair, and A Rivetti. BMJ 2008. 10 January 2008. https://doi.org/10.1136/bmj.39393.510347.BE
- *Here I would argue their evidence should not lead to the conclusion that these measures are highly effective. There must be three healthcare workers using N95 masks to prevent one infection. No wonder SARS outbreak occurred in so many hospitals.
Indeed, the author of the present article says “What if a however partial protection afforded by leaky surgical or even self-made masks reduces transmission probability to an extent that is similar to that of the recommended (equally imperfect) distancing by more than 6 feet from each other or
not touching your face? It could then double the impact of non-pharmacological intervention (NPI) on flattening the curve.” However, he presents no evidence at all that this may be true. The study regarding PPE versus influenza that I mentioned above actually leads to a rather different answer
than the author would have us speculate—we would be wasting resources on useless efforts.
There is a common saying that desperate times call for desperate measures. I do not think we’re yet in desperate times—things are nowhere near as bad as they could be with a more virulent virus —but we could certainly get there is we were to allocate resources to masking the entire population, possibly worsening infection rates, not attenuating them. Even if we are in desperate times, I do not think these times call for ineffective measures.