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WHN Science Communications

RE: Respiratory Pathogens: Pandemic Preparedness Guidance by WHO

  • Keywords:
  • Air Filter
  • Clean Air
  • Masks
  • Mitigation Strategies
  • Ventilation
  • Publication date:

    Submission date:


    The draft of the World Health Organization’s “Respiratory Pathogens: pandemic preparedness guidance” provides a framework and outlines core capacities for coordinated planning of prevention, preparation, response, and recovery strategies, drawing on the lessons learned from the COVID-19 pandemic.

    Despite the ongoing COVID-19 pandemic, the surge of influenza and RSV, and the reemergence of MERS, this draft is missing essential information about airborne transmission and protection. There is no mention of the words “airborne” and “mask,” and although ventilation is mentioned, filtration is not. Crucially, the importance of respiratory protection (respirators/masks)–a key lesson to be learned–is not discussed.

    Preventing the spread of airborne pathogens must be a top priority, and clear, unequivocal guidance must be given to leadership, medical professionals, and the public about the need to mitigate against sharing unfiltered air. This should include mandates for the use of face masks, physical distancing, and improved ventilation in public and private spaces.

    In particular:

    • SARS-CoV-2 and other respiratory viruses are often found in airborne particles (aerosols) and are transmitted by inhalation of infectious aerosols which are exhaled by infected, contagious individuals who may or may not have symptoms and who may or may not test positive.
    • These aerosols spread and linger in indoor air, remaining infectious for hours.
    • Sharing air in indoor settings and outdoors, particularly in close proximity or in crowded settings, is the primary way that SARS-CoV-2 is transmitted.
    • Clearly indicate that aerosol transmission occurs through breathing and talking, as well as singing, sneezing, and coughing.
      • Many institutions erroneously regard aerosol transmission as occurring only during specific actions called “aerosol generating procedures.” 
    • The mandating of respiratory protection equipment, defined as the use of well-fitting, high-filtration respirators/masks, FFP2/FFP3 or N95/KN95/KF94 equivalent or better, is specifically advised for individuals and communities as well as for health care workers.
      • By contrast, (a) loose-fitting surgical masks are intended for protection against ballistically moving droplets, and are not sufficiently protective against aerosols, (b) cloth masks offer minimal protection, if any, and (c) reliance on lower quality respiratory protection has been and continues to be a key limitation of the current COVID-19 approach globally.
      • Oblique references to “respiratory hygiene” and “the right measures” are insufficient to promote effective public health protection measures.
    • Ventilation and filtration of indoor air in public buildings and residences is key.
      • To reduce viral concentration in the air, the mechanical ventilation or HVAC system (Heating, Ventilation, Air Conditioning) should evacuate stale air from spaces and replace it with fresh air intake as much as possible. Older HVAC systems may not be able to provide enough filtration to maintain safe CO2 levels without excessive system strain. If existing ventilation is insufficient,HEPA filtration, utilizing commercial air purifiers or effective DIY alternatives such as Corsi-Rosenthal boxes, should be added as an adjunct for buildings that may not be amenable to ventilation upgrades, in areas of high density or close proximity occupancy, and in settings with variable levels of resources.
    • Vaccines for emerging pathogens, including SARS-CoV-2, vary in their effectiveness. Vaccines may not adequately prevent transmission, and vaccines may not prevent the long term effects of infection. Vaccine-only approaches are inappropriate in pandemic settings, and a multilayered approach to stopping viral transmission should be implemented.
    • The implementation of prevention measures, including but not limited to vaccines, requires community-based approaches that engender trust. When effective communication of the risks and consequences of virus infection are not adequately performed, misinformation gives rise to hesitancy in public adoption, e.g. vaccine hesitancy, that undermines the public health response.
    • Unabated viral spread (infection-based herd immunity) approaches have been ineffective and cause both short and long term harm. Sustained viral spread leads to development of new viral variants, which may evade immunity and may render therapeutics ineffective.

    Frank, honest public communication and education about airborne virus spread, coupled with updated guidance about respiratory protection and management of indoor air, are central to successful efforts to control pandemics, and are required to correct the missteps taken during public health response to the COVID-19 pandemic and to prevent future disasters.

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