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October 26, 2020

Preventing the Spread of SARS-CoV-2 With Masks and Other “Low-tech” Interventions

Author Affiliations
  • 1National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
JAMA. 2020;324(19):1935-1936. doi:10.1001/jama.2020.21946

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), has caused a global pandemic of historic proportions in the 10 months since cases were first reported in Wuhan, China, in December 2019, with worldwide morbidity, mortality, and disruptions to society.

Ultimately, a safe and effective vaccine will be essential to control the pandemic and allow resumption of the many activities of normal life. While results of phase 3 trials for multiple candidate vaccines are on the near horizon, “low-tech” tools to prevent the spread of SARS-CoV-2 are essential, and it must be emphasized that these interventions will still be needed after a vaccine is initially available. Even if one or more vaccines have high efficacy and uptake in the population, it will take at least several months for enough people to be vaccinated to confer herd immunity on a population basis.

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    7 Comments for this article
    Face masks
    S Hasanain, M.D. | Cardiologist, Gottlieb Memorial Hospital
    I wish this article and face masking advice by Dr. Fauci appeared in February or March, before we had over 8.9 million cases and 230,000 deaths, not to mention many trillions in financial losses. 
    How We Know Masks Work
    Russell Fitton, DDS | Private Practice
    The best evidence that masks work doesn't come from theoretical papers or assumptions based on observation. Masks work because dentistry has been using masks since about 1986. Dentists have worn them through HIV, all the hepatitis outbreaks, SARS, H1N1,etc. There has never been an outbreak of any of the above in a dental office setting even with all the aerosols generated from dental handpieces and oral ultrasonic cleaning instruments. If you want people to understand that masks work just tell them to ask their dentist. It's interesting also that the infection rate for Covid-19 for dentists is less than 1%. 
    Additional Low Tech Interventions
    Dr Mubarak M Khan, MBBS, DLO, DNB (ENT) | Sushrut ENT Hospital & Dr Khan’s Research centre, Talegaön Dabhade, Pune, India
    We are practising the following additional simple things in our daily routine in an office-based otolaryngology practice in the last 6 months:

    1. P = PPE: creating a barrier between workers and the virus and other airborne diseases  (mask, gown, gloves, cap & faceshields, sanitizers)

    2. U = UVc: Ultra Violet C germicidal light or Chemical disinfection of Environmental air s to reduce viral load. This must be specifically utilised for all OPD, Hospitals, Operation Theatres (OTs), all crowded places

    3. B = Betadine: 0.5% povidone iodine gargles and nose drops for all patients before examination and
    all health care workers who are busy treating patients irrespective of Covid status. 

    4. V = Ventilation: Reverse ventilation filters (Exhaust Fan Filters) for air purification in hospitals, wards, ICU, OT. We have developed simple air filters from exhaust fans and surgical mask material and use them in our Opd wards and OTs. The same highly economical exhaust filter can be used in crowded areas and small homes (cost required to modify existing exhaust fan will be only $25 to $30). And similar high end exhaust filters can be used in high crowded places (like malls, local trains, hotels, restaurants, multiplexes)

    Stay Safe .... Stay Healthy

    Sincere regards

    Dr Mubarak Muhamed Khan
    Dr Sapna Ramkrishna Parab
    Consultant & Directors

    Sushrut ENT Hospital & Dr Khan’s Research centre, Talegaön Dabhade, Pune, India

    1. Repurposing 0.5% povidone iodine solution in otorhinolaryngology practice in Covid 19 pandemic.
    Khan, Mubarak Muhamed; Parab, Sapna Ramkrishna; Paranjape, Mandar.
    Am J Otolaryngol ; 41(5): 102618, 2020.
    Article in English | MEDLINE | ID: mdl-32574894
    2. 0.5% povidone iodine irrigation in otorhinolaryngology surgical practice during COVID 19 pandemic.
    Khan, Mubarak Muhamed; Parab, Sapna Ramkrishna.
    Am J Otolaryngol ; 41(6): 102687, 2020 Aug 19.
    Article in English | MEDLINE | ID: covidwho-720408
    3. CIE (2003) CIE 155:2003 Ultraviolet Air Disinfection. Freely available at
    4. Welch, D., Buonanno, M., Grilj, V., Shuryak, I., Crickmore, C., Bigelow, A.W., Randers- Pehrson, G., Johnson, G.W. and Brenner, D.J. (2018) Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases. Scientific Reports 8(1): 2752.
    DOI: 10.1038/s41598-018-21058-w
    5. CIE Position Statement on Ultraviolet (UV) Radiation to Manage the Risk of COVID-19 Transmission
    May 12, 2020
    Evidence is Clear and We Can Prevent Other Respiratory Infections
    Erand Llanaj, MPH, MSc, PhD | Department of Public Health and Epidemiology, Faculty of Medicine, Uiversity of Debrecen
    Lerner, Folkers, and Fauci outline the evidence and arguments for the utility of universal masking in these times that alternative effective solutions are scarce. We know what to do and we need to get the message out there to fight the rapid 'infection' of misinformation. Face coverings are saving lives during the coronavirus pandemic, but debate trundles on. An important piece of the argument to be considered is that on a population level masks prevent a lot of unnecessary suffering and deaths from COVID-19. Compliments to the authors for having the courage to advance this narrative.
    Konda Filtration Efficacy Data
    James Radney, Ph.D. Chemistry | NIST
    There is an important caveat about this Viewpoint's reference 6 (1) that this viewpoint has failed to acknowledge. The authors of the Konda study drew the conclusion that  "hybrid masks offer slightly inferior [efficacy] to the N95 mask above 300 nm, but superior for particles smaller than 300 nm,” not that “the filtering efficacy of some materials used in cloth masks may approach that of surgical masks” as suggested in this Viewpoint.

    The original and quite remarkable conclusions of the Konda manuscript could not be replicated in similar subsequent studies [e.g. 2, 3] as the experiments were conducted
    at conditions well below physiologically relevant causing their measured filtration efficacies to disagree with those of the larger community. As a result, the authors have issued a correction to the original manuscript (4).

    This correction has also been accompanied by multiple letters to the editor concerning their results [5-7]. As noted by Rule [6],

    “Given these problems with the experimental design, we believe that the authors’ conclusions can lead the public to overestimate the protection these fabric masks can truly offer. As of this writing on June 30, 2020, the article has been viewed over 350,000 times. We encourage readers to consider the broader literature in which sound aerosol science has shown lower filtration efficiencies for fabric materials”.

    This also highlights the need for the community to follow established protocols (e.g. Parts 3 and 5 of EN 1822 or ISO 29463) when assessing the effectiveness of materials in cloth face coverings. Regardless, the truth remains that the wearing a cloth face covering is an effective means of source control for slowing the transmission of COVID-19.


    [1] Konda  A, Prakash  A, Moss  GA, Schmoldt  M, Grant  GD, Guha  S.  Aerosol filtration efficiency of common fabrics used in respiratory cloth masks.   ACS Nano. 2020;14(5):6339-6347. doi:10.1021/acsnano.0c03252
    [2] Zangmeister, C. D.; Radney, J. G.; Vicenzi, E. P.; Weaver, J. L., Filtration efficiencies of nanoscale aerosol by cloth mask materials used to slow the spread of sars-cov-2. ACS Nano 2020, 14, 9188 - 9200.
    [3] Drewnick, F.; Pikmann, J.; Fachinger, F.; Moormann, L.; Sprang, F.; Borrmann, S., Aerosol filtration efficiency of household materials for homemade face masks: Influence of material properties, particle size, particle electrical charge, face velocity, and leaks. Aerosol Sci. Technol. 2020, 1-17.
    [4] Konda, A.; Prakash, A.; Moss, G.; Schmoldt, M.; Grant, G.; Guha, S., Correction to aerosol filtration efficiency of common fabrics used in respiratory cloth masks. ACS Nano 2020, 14, 10742 - 10743. 
    [5] Carr, I. A.; Hariharan, P.; Guha, S., Letter to the editor regarding aerosol filtration efficiency of common fabrics used in respiratory cloth masks. ACS Nano 2020, 14, 10754-10755.
    [6] Rule, A.; Ramachandran, G.; Koehler, K., Comment on aerosol filtration efficiency of common fabrics used in respiratory cloth masks: Questioning their findings. ACS Nano 2020, 14, 10756-10757.
    [7] Hancock, J. N.; Plumley, M. J.; Schilling, K.; Sheets, D.; Wilen, L., Comment on “aerosol filtration efficiency of common fabrics used in respiratory cloth masks”. ACS Nano 2020, 14, 10758-10763.
    National Mask Mandate and Lockdown
    Hunasikatti Mahadevappa, MD, FCCP | Fairfax Hospital, Falls Church, VA 22042
    The authors state that ' The implementation of mandates averted more than 200 000 cases of COVID-19 by May 22, 2020, according to modeling estimates". When there is so much data regarding the effectiveness of measures like mask-wearing, it is somewhat surprising why the COVID-19 Task Force did not recommend a national mandate. This is the only effective solution which should have been in the guidelines-even if this is opposed by the political establishment. At least medical experts would have done their job with clarity and directive to avoid deaths.

    We have to learn from the success stories of
    China and Europe. China's approach to the coronavirus is characterized by the initial draconian, 76-day lockdown seen in Wuhan, the central Chinese city where cases of the virus were first detected late last year. China's success in controlling the coronavirus is not so much a product of those early control measures -- though these have been utilized effectively to halt regional flare-ups -- but how the country handles things after people are allowed to move around again. In particular, China's ability to track, contact trace cases across the country whenever there is the suggestion of a new cluster of infections has enabled the government to respond quickly and bring local epidemics under control.

    These are extraordinary times and we are in a medical emergency. We should declare an emergency and do what is necessary to control the pandemic. South Korea is a Democratic country . In SK, if people do not wear masks on public transportation and at demonstrations, as well as medical and care facilities, they will face a fine of up to 100,000 won ($87). Operators of those facilities and rally organizers will be fined up to 3M won for failing to ensure that users or participants comply with the requirement. 

    All public health issues must remain bipartisan issues. No politician should be able to override the collective guidelines issues by CDC in consultation with other agencies. It is time to appoint chairpersons of public health agencies so they can function independently with no fear of reprisal from any one.

    The US used to be a leader in epidemiological interventions and the whole world used to follow CDC guidelines. Today we are looking at countries like China, South Korea and Germany for their method of pandemic control. This can only be reversed if both parties decide that it is in the best interest of the nation , not to interfere with clinical decisions regarding public health formulated by the federal agencies
    ( These are my personal views and do not represent the policies of any organization)
    Pharyngeal Antisepsis
    Bruce Davidson, MD MPH | Providence Health Services, Seattle WA
    Several common, very inexpensive, proven-safe mouthwashes (e.g., Listerine Ultra, $0.15/dose) are also shown (1, 2) to rapidly inactivate SARS-CoV-2 by > 4 logs (e.g., 50,000 to <5 viruses) with 60 seconds exposure. Gargling and swishing an effective antiseptic mouthwash for 60 seconds is shown (3) to reduce culture-positivity 5 minutes later of pharyngeal pathogen Neisseria gonorrhea (by >50%) compared to saline (p=0.013). Healthy adults don't aspirate while awake but are repeatedly proven to do so during sleep (4,5).

    Preclinical evidence is repeated and robust. Clinical trials are not needed when the intervention has an indisputable safety record, consumes trivial
    resources ($0.15 and 60 seconds before sleeping), and there is no time to confirm efficacy. This is why the 9 different US-available injected influenza vaccines with different and some new viral proteins have not been tested in clinical trials. Surveillance estimates efficacy post-hoc, as it will with this year's flu vaccines and would with pharyngeal antisepsis before sleep.

    Why not try to persuade the public to participate to reduce SARS-CoV-2 prevalence where we dwell?

    1. Meister TL et al, J Infect Dis, 2020 Sep 14;222(8):1289-1292. doi: 10.1093/infdis/jiaa471.
    2. Meyers C et al, J Med Virol 2020:1-8.
    3. Chow EPF, et al. Sex Transm Infect 2017;93:88–93.
    4. Huxley EJ et al, Am J Med 1978;64:564-8
    5. Gleeson K et al, CHEST 1997;111:1266-72