The Science of Masks Part 1: Intro to SARS-CoV-2
All about the scientific literature on masks, and a bit about a mostly useless organization called the CDC
Welcome to my big, long, ranty rant about the CDC, misrepresentations of science, and a little bit about a 1990s sitcom. And this is just Part 1 of many (ten total) such rants. Sometimes there are ending summaries; this is especially useful if you, like me, start articles at the end and work backwards.
Warning: Boring introduction
[While typing this I’m also side-eye watching season one of a romantic comedy from the 1990s called Dharma & Greg so at least I’m not bored, but you might be. We’re on episode 1, “Pilot.” ]
Now on to the CDC.
In the mistaken expectation that government is there to help them, many Americans look to the Centers for Disease Control and Prevention for health guidance. When COVID-19 became the apocalypse du jour the CDC issued guidance that we should all begin wearing face masks to “slow the spread” of the disease - a surprising proclamation given that masks have existed for decades (at least) and we’ve never before been told their use is critical to Pubic Health.
Lucky for us our betters at the CDC told their most-junior intern to put together a web page explaining to us ignorant rubes the value of masks - and the intern included references. So off I went in early 2020 to that delightful web page (titled Considerations for Wearing Masks1) and started reading.
By 20 August 2020 (when someone asked me to write all this down) the CDC’s intern had accumulated nineteen references, and those fall into three categories:
Nine references about transmission of the virus by people who are asymptomatic or presymptomatic.
Two references about aerosol and droplet transmission.
Eight references to mechanistic studies on the effectiveness of masks.
Based on those references, the conclusion that masks should be worn to prevent infection appears to be the result of the following reasoning:
People can transmit the virus to others even if they don’t have symptoms.
The virus has been found in respiratory droplets and aerosols.
Lab experiments with masks have shown they can block droplets and aerosols.
Therefore mask use, even by apparently healthy people, will reduce the chance of transmitting or being infected by the virus. That’s why we wear masks every winter and no one ever gets the flu.
Reading the intern’s work, it’s shocking to see how little evidence there was to support what eventually became draconian restrictions on the simple act of breathing. But obedient Americans went about muzzling their own children despite the paucity of evidence masks were either necessary or effective. Nothing to worry about - it’s not like blindly doing whatever we’re told could lead to something like forced injections of experimental drugs, right? Right?
The goal of this series is to review the evidence on masks and learn how ridiculous the proclamations coming from health officials truly are. This first post will take a short look at COVID-19 is, and provide some background on the transmission of disease. The following posts will contain closer looks at each of the references used by the CDC, as well as the clinical studies that the CDC conspicuously failed to mention - despite (big shock) having funded some of them.
Setting the rules
Since this series is about assessing the published scientific literature relevant to the subject of masking, for this ten-post extend rant review we’ll be following a few guidelines on information sources.
The following posts use information from:
References provided by the CDC
Other articles, letters, and peer reviewed studies published in scientific journals
Reports compiled by the World Health Organization and the National Academy of Sciences
A textbook on virology (because I’m not a virologist)
Some other sources are specifically not being used:
No information from Wikipedia (Directly quoting Wikipedia for medical information is grounds for a spanking.)
No quotes from news media (If they have a source, quote the source.)
No information from social media (For obvious reasons. If those reasons aren’t obvious, I can’t help you.)
So strap in and let’s learn a little bit about viral diseases. Dharma and Greg just met and are married less than a day later so things are about to get crazy. In the show, not this blog. This blog is perfectly sane and I took my medication today.
[Over to my right, Dharma is explaining why she loves going to baseball games:
“You know, you can scream anything you want at a baseball game and it doesn’t even have to make sense.”
“Come on big guy, drive your coffee table to Idaho! Woo! Nectarine time! Comb your frog!”
Very appropriate, considering the current topic. When dealing with the CDC, it’s best to accustom oneself to mentally processing non sequiturs.]
What is COVID-19? What is SARS-CoV-2? How many acronyms do I need to memorize?
COVID-19 stands for Corona Virus Disease 2019, and according to researchers COVID-19 is caused by a virus named SARS-CoV-2 (Severe Acute Respiratory Syndrome Corona Virus 2).
SARS-CoV-2 is the seventh known human coronavirus (HCoV). Coronaviruses have been around awhile, and can cause respiratory and enteric (intestinal) diseases.
Coronaviruses are RNA viruses of the family Coronaviridae, known to cause respiratory and enteric disease in humans and animals. Coronaviruses are second to RV* as a cause for the common cold. They may also cause other respiratory tract infections, such as pneumonia and pharyngitis. (La Rosa et al. 20132)
(*RV is rhinovirus)
So if you have a pulse and are older than about 0, you have most likely been exposed to human coronaviruses in the past. Prior to SARS-CoV-2, there were six known human coronaviruses. The first four of those six are believed to cause many cases of common colds.
The first human coronaviruses (HCoV) were described in the 1960s and were designated HCoV-229E and HCoV-OC43. There are now 4 endemic* HCoV known (HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1) that circulate worldwide in the human population. In most cases, these endemic HCoV cause relatively mild diseases of the upper and lower respiratory tract and are estimated to account for about a third of all ‘common colds’ in humans. (Ludwig and Zarbock 20203)
(* Endemic is a useful little term that means “persisting in a population for a long period without reintroduction of the causative agent from outside sources.” Flint et al., Principles of Virology, 20154)
Added to these four endemic viruses they describe two newer coronaviruses, the original SARS-CoV which first appeared in 2002, and later MERS-CoV which appeared in 2012 (MERS is Middle East Respiratory Syndrome, so called because that is where it first appeared).
The situation completely changed with the appearance of the SARS-CoV. This virus caused serious human respiratory diseases in China in 2002–2003.
While no human infections with the original SARS virus have been reported since 2004, another CoV dangerous for humans emerged in 2012. The MERS-CoV was isolated for the first time from a patient who was hospitalized with acute pneumonia in Saudi Arabia. (Ludwig and Zarbock 2020)
In 2019 another new coronavirus emerged (natural or man-made is still being debated, but the conclusion of that debate really has no bearing on all of this). An article published 24 January 2020 described patients with pneumonia, and they concluded that the source was a novel (new) coronavirus.
In late December 2019, several local health facilities reported clusters of patients with pneumonia of unknown cause that were epidemiologically linked to a seafood and wet animal wholesale market in Wuhan, Hubei Province, China. On December 31, 2019, the Chinese Center for Disease Control and Prevention (China CDC) dispatched a rapid response team to accompany Hubei provincial and Wuhan city health authorities and to conduct an epidemiologic and etiologic investigation. We report the results of this investigation, identifying the source of the pneumonia clusters, and describe a novel coronavirus detected in patients with pneumonia whose specimens were tested by the China CDC at an early stage of the outbreak. (Zhu et al. 20205)
By March the World Health Organization had named the new baby COVID-19 and concluded the cause was a new virus named SARS-CoV-2.
In December 2019, a cluster of patients with pneumonia of unknown cause was observed in Wuhan, China. A novel coronavirus was identified as the causative pathogen, provisionally named as 2019 novel coronavirus (2019‐nCoV) by the World Health Organization (WHO). On 11 February 2020, WHO named this novel coronavirus pneumonia as “COVID‐19” (coronavirus disease 2019). On the basis of phylogeny, taxonomy, and established practice, the Coronavirus Study Group of the International Committee on Taxonomy of Viruses formally recognizes this virus as a sister to severe acute respiratory syndrome coronavirus (SARS‐CoV) and renamed it as SARS‐CoV‐2. (Wang et al. 20206)
To summarize, in late 2019 doctors in China reported an outbreak of a new type of pneumonia in Wuhan, China, and this new pneumonia-like disease is now called COVID-19. They determined the pathogen causing this disease is a new human coronavirus which they referred to as 2019-nCoV, and which is now officially called SARS-CoV-2.
But how is this virus (and other viruses) transmitted? My personal belief is that all diseases are spread by small children who like to put one of my french fries in her mouth and then put it back on my plate.
But virologists and epidemiologists have their own ideas. Let’s see what they think.
[On the show, Dharma and Greg are having a very Dharma & Greg conversation. Greg learns she wants to have kids:
Greg: “Oh good, you want to have children.”
Dharma: “Yeah, unless you wanna have ‘em!”]
Transmission of viruses, not a simple subject and clearly outside the mental capacity of most CNN contributors
Viral transmission between people can occur several ways: through direct person to person contact, through indirect contact (both people touched the same object), or through droplets or aerosols from breathing, coughing or sneezing. From Transmission routes of respiratory viruses among humans:
Respiratory viruses spread via three different transmission routes: contact (direct or indirect), droplet and aerosol transmission. Contact transmission refers to direct virus transfer from an infected person to a susceptible individual (e.g. via contaminated hands) or indirect virus transfer via intermediate objects (fomites*). Transmission of virus through the air can occur via droplets or aerosols. The commonly accepted cut-off size between the large droplets and small aerosols is 5 μm, although this varies considerably between studies, ranging up to 12 μm. Droplets generated during coughing, sneezing or talking do not remain suspended in air and travel less than 1 m before settling on the mucosa of close contacts or environmental surfaces. Aerosols have a slow settling velocity, thus they remain suspended in the air longer and can travel further. (Kutter et al. 20187)
(*fomite: An object that can act as a vehicle for the transmission of microorganisms. (Flint 2015))
Droplets fall quickly to the ground, generally traveling less than about three feet (1 meter), but aerosols can remain suspended in the air for a very long time. How many people become infected by these routes and by fomites is not known.
Studies on the transmission routes of respiratory viruses have been performed since the beginning of the 20th century. Despite this, the relative importance of transmission routes of respiratory viruses is still unclear, depending on the heterogeneity of many factors like the environment (e.g. temperature and humidity), pathogen and host. (Kutter et al. 2018)
This statement is also echoed by one of the sources cited by the CDC, a “rapid expert consultation” provided by Dr. Harvey Fineberg at the National Academies of Sciences, Engineering, and Medicine.
However, for no respiratory virus is the exact proportion of infections due to air droplet, aerosol, or fomite transmission fully established, and many individual factors and situations may contribute to the importance of each route of transmission. (Fineberg 20208) (emphasis added)
Discussing transmission of the original SARS outbreak from 2002 - 2004, Kutter also pointed out the frequency of nosocomial (hospital acquired) infections.
The SARS outbreak was primarily linked to healthcare settings, with ≥49% of the cases linked to hospitals, most probably caused by aerosol-generating procedures on severely ill patients. Aerosol-generating procedures like intubation, the use of continuous positive pressure ventilation and drug delivery via nebulizers are likely to produce ‘fine infectious droplets’, which travel further than droplets from coughs. (Kutter et al. 2018)
The spread of SARS to health care workers, caused by procedures that create aerosols, was also noted by La Rosa. They explain that hospital acquired infections of both staff and patients is a well known issue.
In addition, many health care workers were infected after endotracheal intubation and bronchoscopy procedures which often involve aerosolization.
The vast majority of studies reviewed here concern hospital and other health facilities where viruses are a well-known cause of occupational and nosocomial infections. (La Rosa et al. 2013)
The issue with hospital acquired infections of SARS-CoV-2 was also reported by Wang:
Similar to SARS and MERS, nosocomial transmission was a severe problem to COVID‐19, and even worse.
A lot of respiratory treatments for critically ill patients are deemed as high‐risk factors for nosocomial transmission, such as intubation, manual ventilation by resuscitator, noninvasive ventilation, high‐flow nasal cannula, bronchoscopy examination, suction and patient transportation. (Wang et al. 2020)
So viruses are transmitted by several routes, and no one really knows how important each of these routes is. How effective are masks? The statement, “experiments with face masks have shown they can block droplets and aerosols,” is true but it’s not the same as “masks prevent infection” and making that little logical leap requires evidence.
A number of experiments have clearly shown that various types of masks and mask materials will reduce the amount of droplets, aersosols or pathogens (viruses, bacteria, fungi) in the air passing through them. But this is not the same as proving the likelihood of infection is reduced. The best way to prove that would be to conduct randomized controlled trials (RCTs) and observe whether the mask wearers get fewer infections. (I can’t believe I even have to explain that part but someone from CNN might be reading this.)
As will be discussed later, those experiments have been inconclusive. The majority find no improvement from masks, a small number see reduced infections, and a small number find more infections among the mask wearers. In one of the largest randomized studies performed in hospitals, for example, the cloth mask group had more infections than the control group (MacIntyre et al. 20159) and as a result the authors specifically recommended against the use of cloth masks by healthcare workers.
This study will be discussed in more detail later, but for now remember there are more than two possible outcomes from wearing a mask: masks have no impact on infections, they may help reduce infections (although perhaps only a bit), or they may result in more infections (although perhaps only a bit). More evidence for some potential negative consequences of masks will be also be reviewed, after looking at the evidence supporting their use.
In the next post, we will start to look at the references cited by the CDC when they told us all to mask up or else be subjected to endless hours of Anthony Fauci interviews and Congressional testimony.
I honestly think the world would be a better place immediately if we could just replace all Fauci interviews with clips from 1990s romantic comedies. I’m confident I already know which of those two things has done more to benefit humanity.
Next up:
The Science of Masks Part 2: “The Intern’s Web Page” and Dharma & Greg Episode 2: “And the In-Laws Meet.”
Current page: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover-guidance.html
Archived page: https://web.archive.org/web/20200703223648/https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover-guidance.html
La Rosa G, Fratini M, Libera S D, Ioconelli M, Muscillo M. Viral infections acquired indoors through airborne, droplet or contact transmission. Ann Ist Super Sanità 2013, Vol. 49, No. 2:124-132. DOI: 10.4415/ANN_13_02_03. https://pubmed.ncbi.nlm.nih.gov/23771256/
Ludwig S, Zarbock A. Coronaviruses and SARS-CoV-2: A Brief Overview. Anesth Analg. 2020;131(1):93-96. doi:10.1213/ANE.0000000000004845. https://pubmed.ncbi.nlm.nih.gov/32243297/
J. Flint, V.R. Racaniello, G.F. Rall, A.M. Skalka. Principles of Virology, Fourth Edition, Bundle. American Society of Microbiology (2015). doi:10.1128/9781555819521. ISBN 978-1-55581-952-1.
Zhu N, Zhang D, Wang W, Li X, Yang B, Song J, Zhao X, Huang B, Shi W, Lu R, Niu P, Zhan F, A Novel Coronavirus from Patients with Pneumonia in China, 2019. N Engl J Med 2020; 382:727-733 DOI: 10.1056/NEJMoa2001017. https://pubmed.ncbi.nlm.nih.gov/31978945/
Wang Y, Wang Y, Chen Y, Qin Q. Unique epidemiological and clinical features of the emerging 2019 novel coronavirus pneumonia (COVID-19) implicate special control measures. J Med Virol. 2020;92(6):568-576. doi:10.1002/jmv.25748. https://pubmed.ncbi.nlm.nih.gov/32134116/
Kutter JS, Spronken MI, Fraaij PL, Fouchier RA, Herfst S. Transmission routes of respiratory viruses among humans. Curr Opin Virol. 2018;28:142-151. doi:10.1016/j.coviro.2018.01.001. https://pubmed.ncbi.nlm.nih.gov/29452994/
National Academies of Sciences, Engineering, and Medicine. 2020. Rapid Expert Consultation on the Possibility of Bioaerosol Spread of SARS-CoV-2 for the COVID-19 Pandemic (April 1, 2020). Washington, DC: The National Academies Press. https://doi.org/10.17226/25769
MacIntyre, C. R.; Seale, H.; Dung, T. C.; Hien, N. T.; Nga, P. T.; Chughtai, A. A.; Rahman, B.; Dwyer, D. E.; Wang, Q. A Cluster Randomised Trial of Cloth Masks Compared With Medical Masks in Healthcare Workers. BMJ. Open 2015, 5, No. e006577. https://pubmed.ncbi.nlm.nih.gov/23413265/