SARSCoV2 / COVID19 Information Based on a Brief Review of the Literature
Credit to Rodney Rohde, PhD, MS, SV/SM/MB(ASCP), Chair, TXST Clinical Lab Science Program
Coronaviruses are everywhere. They are the second leading cause of the common cold (after rhinoviruses) and until recent decades, rarely caused any disease more serious than a common cold in humans. Coronaviruses are a large family of viruses which may cause illness in animals or humans. In humans, several coronaviruses are known to cause respiratory infections ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The most recently discovered coronavirus, SARS- CoV-2, causes coronavirus disease COVID-19 and is thought to have originated in Wuhan, China in December of 2019. The first coronavirus was isolated in 1937. Some cause illness in people and others circulate among other animals, including camels, cats and bats. Since its discovery, related coronaviruses have been found to infect cattle, pigs, horses, turkeys, cats, dogs, rats, and mice. The first human coronavirus was cultured in the 1960s from nasal cavities of people with the common cold.
The four major categories of coronavirus are known by the Greek letters’ alpha, beta, delta and gamma. Only alpha and beta coronaviruses are known to infect humans. These viruses spread through the air and are responsible for about 10-30 percent of colds worldwide. Long known to cause upper respiratory infections, coronaviruses were not felt to significantly cause pneumonia until relatively recently. Seven human coronaviruses (HCoVs) have now been identified: HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1, SARS-CoV (which causes severe acute respiratory syndrome), MERS-CoV (Middle East respiratory syndrome), and now SARS-CoV-2. All appear to be established human pathogens with worldwide distribution, causing upper and lower respiratory tract infections with some mortality.
Coronaviruses are zoonotic, meaning they can be transmitted between animals and people, but most infect only their specific animal host. Rarely, animal coronaviruses can evolve to infect and spread among people. This was the case with Severe Acute Respiratory Syndrome Coronavirus (SARS- CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV). SARS killed nearly 10% of the 8,096 people who fell ill in 29 countries. A total of 774 people died, according to the World Health Organization. MERS is even more deadly, claiming more than 30% of people it infects. Since 2012, MERS has caused 2,494 confirmed cases in 27 countries and killed 858 people. SARS-CoV and MERS-CoV generally spread between people who were in close contact, which resulted in many fatalities of healthcare workers. In early through mid-January 2020, the SARS-CoV-2 epidemic in Wuhan had an Rt (reproductive rate) of 3 to 4. In other words, each case spread to an average of 3 to 4 others. Generally, it is believed that the Rt of SARS-CoV-2 is somewhere in the range of 1.4 to 6.49, with a mean of 3.28, a median of 2.79. As of June 16, 2020, the global number of cases for the ongoing SARS- CoV-2 pandemic is 8,063,488 with 437,532 deaths (fatality rate of 5.4%). In the U.S., there are currently 2,114,180 cases with 116,130 (fatality rate of 5.5%). Lastly, in Texas there are currently 89,108 cases with 1,983 deaths (fatality rate of 2.2%). Cases and mortality are at this time fluid and changing rapidly on a daily basis. It is important to point out that SARSCoV2 is a “novel” or new virus. In common terms, this means that the human population has never seen this particular virus immunologically. Thus, humans have no immune memory (naïve) of the microbe and the virus is able to transmit more efficiently between people and over geographic areas more quickly.
The topic of facemasks to prevent microbial infection or transmission is a complex topic. I will present the general information and evidence surrounding the types and use of facemasks. At the beginning of this pandemic, there was some confusion over the use of masks. Viruses are some of the smallest known microbes known to humankind. It is important to understand the sizes of microbes and their mode of spread to begin a discussion about masks and their potential use in reducing transmission of infectious agents.
Most microbes are unicellular and not visible without some sort of magnification like a laboratory microscope. Some unicellular microbes (few) are visible to the naked eye, and some multicellular organisms that are microscopic (pinworms for example) are visible without a microscope. However, single bacteria and viruses are not visible without a microscope. An object must measure about 100 micrometers (µm) to be visible without a microscope, but most microorganisms are many times smaller than that. In fact, a typical animal cell measures roughly 10 µm across but is still microscopic. Bacterial cells are typically about 1 µm, and viruses can be 10 times smaller than bacteria.
Bacteria (micrometer range) can be viewed with a typical compound light microscope that one uses in most high school and college science labs. Viruses, on the other hand, are so small (nanometer range) that they cannot be viewed unless one uses an electron microscope.
There are a diverse number of masks that one can use in the healthcare or community setting. For the purposes of this paper, I will try to keep it brief regarding the evidence of mask use in the university (community setting). Per the FDA and CDC, N95 respirators and surgical masks are examples of personal protective equipment (PPE) that are used to protect the wearer from airborne particles and from liquid contaminating the face. The Centers for Disease Control and Prevention (CDC) National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) also regulate N95 respirators. It is important to recognize that the optimal way to prevent airborne transmission is to use a combination of interventions from across the hierarchy of controls, not just PPE alone. Cloth masks are not meant to be regulated although research may change this stance going forward.
As mentioned earlier, at the beginning of the SARSCoV2 pandemic many experts in healthcare and public health were not recommending the use of masks for the public (non- healthcare). Generally, the reasoning for this early assessment is that N95 masks, which are a high-grade healthcare PPE, are for healthcare use only. N95 masks (as the name states are about 95% effective in protecting the user) filter out most viruses so it protects the user in healthcare from becoming infected. These masks have a requirement for a “fit test” so that the seal around the face is complete. They are not easily used in public and can be ineffective if not fit tested or used properly. These masks are also in short supply and are prioritized for healthcare personnel and others (public health) who may need them daily.
However, as the pandemic continued to grow in case counts, evidence of asymptomatic / pre- symptomatic transmission, mortality and geography, the scientific community began to study the use of other types of masks that could potentially help with filtering the larger respiratory droplets during exhaling to protect others in the community. These types of masks (surgical and cloth) are used in healthcare and community settings at times.
Surgical masks (also sometimes referred to as isolation, dental, or medical procedural masks) are a loose fitting (not fit tested), disposable device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. They are not to be shared and may come with or without a face shield. These are often referred to as facemasks, although not all facemasks are regulated as surgical masks. Worn correctly, surgical masks can reduce large-particle droplets, splashes, sprays, or splatter that may contain germs (viruses and bacteria), from being inhaled by the user. They can also help reduce exposure of the user’s saliva and respiratory secretions to others. Surgical masks, while more comfortable and simpler to use by anyone, are still primarily recommended by CDC for healthcare use.
With the N95 and surgical / medical mask in mind, the CDC now recommends that members of the public use simple cloth face coverings when in a public setting to slow the spread of the virus, since this will help people who may have the virus and do not know it from transmitting it to others (asymptomatic). Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure.
Therefore, what happened along the way for the CDC (and others in the healthcare, public health, and scientific community) to change their position regarding the use of face masks in public? As the pandemic evolved over the first few months, we learned from several (and a growing number of) studies many people who have COVID19 lack symptoms (“asymptomatic”) and even those who eventually develop symptoms (“pre-symptomatic”) can transmit the virus prior to becoming sick or even showing symptoms. In other words, this means there is a very high likelihood that SARSCoV2 (and other respiratory agents) may spread between people interacting in close proximity—like laughing, singing, speaking, coughing, or sneezing—even when they are not sick.
There is a growing amount of evidence that cloth face masks can provide protection to others and ourselves. While we believe they will never reach the level of N95 mask (or higher-grade masks), there is now scientific proof that wearing a cloth mask or surgical masks can significantly reduce the transmission of SARSCoV2 and likely other respiratory agents. I will briefly mention three such studies but there are numerous other published studies. One recent example of two math models published in the Proceedings of the Royal Society A predicts widespread use of facemasks in public combined with physical distancing or periods of lockdown provides a way to manage the pandemic and reopen the economy while reducing 2nd and future waves of the pandemic. It suggests we should not restrict masks to airplanes, subways, cruise ships and other places of physical distance difficulty. Outbreaks usually start to fade when the reproductive number (average number of other people that a person with the virus infects) – known as the “R’ number, or R0 – falls below 1. The models predicted that if the masks were 75% effective, wearing them could bring the ‘R’ number to below 1 from a high starting point of 4.
Further, if the masks were only 50% effective, the “R’ number could fall to below 1 from a lower starting point of 2.2.
In another study, researchers found in their work that even a homemade facemask made from a cotton T-shirt is at least 90% effective at preventing transmission to other people. The research demonstrated that home fabrics substantially block droplets, even as a single layer and that using two layers, the blocking performance can reach that of surgical masks without significantly compromising breathability.
Finally, a new study out of Texas A&M University in the journal Proceedings of the National Academy of Sciences suggests that among all the strategies for reducing transmission, wearing facemasks may be the central variable that determines the spread of the virus. The research analyzes various mitigation measures put in place in the three major centers of the outbreak— Wuhan, Italy, and New York City— from January 23 to May 9, 2020. Two main takeaway points from the authors is (1) that when paired with the data on how the curve changed in response to the mitigation methods, facemasks are likely the major determinant of how the infection spreads or slows; and, (2) results clearly show that airborne transmission via respiratory aerosols represents the dominant route for the spread of COVID-19.
It is critical to remind everyone that cloth masks do not completely protect us from inhaling this virus or any other virus. We must still practice physical distancing of at least 6 feet or more, maintain hand washing / hand hygiene, and other precautions with mask use (staying home when sick, avoiding others who may be sick, proper air exchange in closed rooms / spaces, and not traveling to high impact areas, etc.)
The CDC has taken the stance that the 6-foot rule should be thought of as a minimum when outdoors but maybe even further apart if indoors with limited air exchanges (most research states a minimum of 12 air exchanges is necessary to reduce transmission of airborne aerosols). Limiting face-to-face contact with others is the best way to reduce the spread of coronavirus disease 2019 (COVID-19). Physical distancing, also called “social distancing,” means keeping space between yourself and other people outside of your home. To practice physical distancing stay at least 6 feet (about 2 arms’ length) from other people.
The WHO has traditionally had a three-foot physical distancing recommendation, which originates from a 1930’s study by Wells, a Harvard researcher who studied tuberculosis. He found that droplets—bits of spit, mucus, and sputum (aka phlegm) expelled as we breathe, cough, or sneeze—tend to land within three feet of where they are expelled. This study has hung on for almost a century and many global experts disagree with it.
In 2003 during the 1st SARS outbreak, scientists believed the three-foot cutoff may not be relevant because of the prevalence of SARS infections within a single flight and concluded that droplets of the virus could actually travel between passengers six feet apart—not three. The study, which looked at just over 100 people and was published in the New England Journal of Medicine, was allegedly the basis for the CDC updating their message to say that people should stay six feet apart to prevent transmission.
Hand hygiene has a long history of strong infection control and prevention data. Without going into the extensive amount of literature to support hand hygiene, I will utilize the CDC primary data and statements regarding this topic.
One would expect that most people understand how critical and important it is to practice hand hygiene at all time, not only during a pandemic. However, even within healthcare we find poor compliance (sometimes with rates around 40-50%) if stringent controls are not in place (observation, professional peer pressure, ongoing education, etc.). By washing our hands, we can help prevent the spread of most germs including transmitting them from one person to the next. We tend to spread germs when we touch our eyes, nose or mouth (common portals of entry for most microbes) with our unwashed hands. One should also wash your hands before preparing food or drinks, after contact with high touch surfaces (think elevator buttons, hand shaking, phones, public touch pads, etc.), and after you blow your nose, sneeze, or cough into your hands. I hope that we understand how critical it is to wash our hands after going to the bathroom too.
To wash your hands wet them with clean, running water (warm or cold and apply soap). Lather your hands by rubbing them together with the soap. Lather the backs of your hands, between your fingers, and under your nails. Scrub your hands and fingers for at least 20 seconds. Rinse your hands well under clean, running water and then dry them with a clean paper or cloth towel. The CDC and others have great training videos for this routine.
Hand hygiene is critical in our response to the ongoing COVID-19 pandemic, especially as we begin to reopen the economy. Practicing hand hygiene, which includes the use of alcohol-based hand rub (ABHR) or handwashing, is a simple yet effective way to prevent the spread of pathogens and infections in healthcare settings. CDC recommendations reflect this important role. Washing hands with soap and water is the best way to get rid of germs in most situations. If soap and water are not readily available, you can use an ABHR sanitizer that contains at least 60% alcohol. You can tell if the sanitizer contains at least 60% alcohol by looking at the product label.
I have attempted to compile some primary literature regarding the SARSCoV2 virus and the disease it causes, COVID-19. I chose to discuss what I and many experts consider three of the main prevention methods – the use of facemasks, physical distancing, and hand hygiene – surrounding the ongoing pandemic. It is important to mention that there are many other infection control and mitigation strategies. Likewise, there is a great degree of complexity in utilizing the different mitigation strategies and tools for any infection control and prevention. This is especially true as we consider the diverse populations and communities we are trying to protect. I also have attempted to utilize a strong science communication writing style to help communicate some of the topics to the public in a way that would be helpful and understood. This paper is not intended to be an all-inclusive literature review or recommendation effort for this ongoing and evolving pandemic.
Literature Regarding Asymptomatic / Pre-symptomatic Carriers
Rothe C, Schunk M, Sothmann P, et al. Transmission of 2019-nCoV Infection from an Asymptomatic
Contact in Germany. The New England journal of medicine. 2020;382(10):970-971.
Zou L, Ruan F, Huang M, et al. SARS-CoV-2 Viral Load in Upper Respiratory Specimens of
Infected Patients. The New England journal of medicine. 2020;382(12):1177-1179.
Pan X, Chen D, Xia Y, et al. Asymptomatic cases in a family cluster with SARS-CoV-2 infection. The Lancet Infectious diseases. 2020.
Bai Y, Yao L, Wei T, et al. Presumed Asymptomatic Carrier Transmission of COVID-19. Jama. 2020. Kimball A HK, Arons M, et al. Asymptomatic and Presymptomatic SARS-CoV-2 Infections in
Residents of a Long-Term Care Skilled Nursing Facility — King County, Washington, March 2020.
MMWR Morbidity and mortality weekly report. 2020; ePub: 27 March 2020.
Wei WE LZ, Chiew CJ, Yong SE, Toh MP, Lee VJ. Presymptomatic Transmission of SARS-CoV-2— Singapore, January 23–March 16, 2020. MMWR Morbidity and mortality weekly report. 2020;ePub: 1 April 2020.
Li R, Pei S, Chen B, et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2). Science (New York, NY). 2020.
Valentyn Stadnytskyi, Christina E. Bax, Adriaan Bax, Philip Anfinrud. The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission. Proceedings of the National Academy of Sciences Jun 2020, 117 (22) 11875-11877; DOI: 10.1073/pnas.2006874117
Literature of Effectiveness of Mask Use in Prevention of Transmission
CDC. The National Personal Protective Technology Laboratory (NPPTL). Respiratory Protection Videos.
June 17, 2020. Accessed from https://www.cdc.gov/niosh/npptl/RespVideos.html
Kai et al. (prepublication). Universal masking is urgent in the COVID-19 pandemic: SEIR and agent based models, empirical validation, policy recommendations– Apr 22
Over 100 prominent health experts call for cloth mask requirements. Masks4All – May 13
Renyi Zhang, Yixin Li, Annie L. Zhang, Yuan Wang, Mario J. Molina. Identifying airborne transmission as the dominant route for the spread of COVID-19. Proceedings of the National Academy of Sciences Jun 2020, 202009637; DOI: 10.1073/pnas.2009637117
Richard O. J. H. Stutt, Renata Retkute, Michael Bradley, Christopher A. Gilligan and John Colvin. A modelling framework to assess the likely effectiveness of facemasks in combination with ‘lock-down’ in managing the COVID-19 pandemic. Proceedings of the Royal Society A: Mathematical, Physical and Engineering SciencesVolume 476, Issue 2238. Published:10 June 2020. https://doi.org/10.1098/rspa.2020.0376
Onur Aydin, Md Abul Bashar Emon, M Taher A Saif. Performance of fabrics for home-made masks against spread of respiratory infection through droplets: a quantitative mechanistic study. medRxiv 2020.04.19.20071779; doi: https://doi.org/10.1101/2020.04.19.20071779
Literature of Physical Distancing
Bourouiba L. Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19. JAMA. 2020;323(18):1837–1838. doi:10.1001/jama.2020.4756
Guidance for Building Operations During the COVID-19 Pandemic. April 8, 2020. Accessed from https://www.jm.com/en/blog/2020/april/guidance-for-building-operations-during-the-covid- 19-pandemic/
W. F. WELLS, ON AIR-BORNE INFECTION: STUDY II. DROPLETS AND DROPLET NUCLEI., American Journal of Epidemiology, Volume 20, Issue 3, November 1934, Pages 611–618, https://doi.org/10.1093/oxfordjournals.aje.a118097
Literature of Hand Hygiene
CDC Core Practices for Infection Prevention in All Healthcare Settings (2017).
Centers for Disease Control and Prevention. Guidelines for hand hygiene in healthcare settings (2002). CDC Handwashing Videos. Accessed June 17, 2020 from https://www.cdc.gov/handwashing/videos.html Food and Drug Administration. Safety and effectiveness for health care antiseptics: Topical antimicrobial drug products for over-the-counter human use (final rule).
Kampf G, Todt D, Pfaender S, Steinmann E. Persistence of coronaviruses on inanimate surfaces and its inactivation with biocidal agents. J Hosp Infect. 2020.
Kratzel A, Todt D, V’kovski P, Steiner S, Gultrom M, Thao TTN, et al. Inactivation of severe acute respiratory syndrome coronavirus 2 by WHO-recommended hand rub formulations and alcohols. Emerg Infect Dis. 2020 Jul [date cited]. https://doi.org/10.3201/eid2607.200915
Rohde, R.E. The Coronavirus Pandemic Isn’t Over: Keep Washing Your Hands As Economies Reopen. June 10, 2020. Accessed from https://www.forbes.com/sites/coronavirusfrontlines/2020/06/10/the-coronavirus- pandemic-isnt-over-keep-washing-your-hands-as-economies-reopen/#74c6e99354f0
Siddharta A, Pfaender S, Vielle NJ, Dijkman R, et al. Virucidal activity of World Health Organization recommended formulations against enveloped viruses include Zika, Ebola, and emerging Coronaviruses. J Infect Dis. 2017
General (other literature)
ACHA Guidelines: Considerations for Reopening Institutions of Higher Education in the COVID-19 Era. June 17, 2020. Accessed from https://www.acha.org/documents/resources/guidelines/ACHA_Considerations_for_Reopening_IHEs_in_t he_C OVID-19_Era_May2020.pdf
CDC. Coronavirus Disease 2019 (COVID-19): Reopening Guidance for Cleaning and Disinfecting Public Spaces, Workplaces, Businesses, Schools, and Homes. June 17, 2020. Accessed from https://www.cdc.gov/coronavirus/2019-ncov/community/reopen-guidance.html
Guidelines: Opening up America Again. June 17, 2020. Accessed from https://www.whitehouse.gov/openingamerica/
Jeffrey D. Smith et al. Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis. CMAJ, May 17, 2016,188(8):567-674.
Lewis J. Radonovich Jr. et al. N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial. JAMA. 2019;322(9):824-833. doi:10.1001/jama.2019.11645
Neeltje van Doremalen et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS- CoV-1. N Engl J Med 2020; 382:1564-1567. DOI: 10.1056/NEJMc2004973 https://www.nejm.org/doi/full/10.1056/nejmc2004973
Rodney E. Rohde. SARCoV2 and COVID19 resource page. June 17, 2020. Accessed from https://rodneyerohde.wp.txstate.edu/sarscov2-covid19-resources/
Texas DSHS. Opening the State of Texas. June 17, 2020. Accessed from https://dshs.state.tx.us/coronavirus/opentexas.aspx