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  • Writer's pictureDr Sonia Doubell

Airborne Transmission of COVID-19 and its Mitigation

Updated: Mar 16, 2021

So pleased to have invested in a medical grade air purification system #MedicAir to destroy virus, bacteria and other pollutants in the air during my consultations with my patients. See article below endorsing good air purification.





Conference Report

IAS COVID-19 2021 — Airborne transmission and its mitigation


Takeaway

  • Analyses of outbreaks during the COVID-19 pandemic have indicated airborne transmission as the most significant mode of transmission in public settings.

  • Sufficient and effective ventilation is a key requirement for mitigating transmission; however, airflow distribution and fresh air supply could be challenging.

  • The speaker, Professor Lidia Morawska from the Queensland University of Technology, Brisbane, Australia, discusses the science of infection transmission and its mitigation.

Key highlights

  • Infections are transmitted either by a close contact with larger droplets or inhaling smaller airborne droplets from an infected individual.

  • These smaller particles are generated by all respiratory activities and vocalization and contain higher loads of SARS-COV-2 than the larger particles.

  • Breathing and speaking are the main sources of virus-laden smaller particles, which remain suspended in air for a long time.

  • Discussing the evidence from outbreaks, the speaker highlights 2 major modes of transmission:

    • Direct transmission by larger or smaller droplets occurring within 1 m proximity of the infected person.

    • Indirect transmission by smaller airborne droplets and droplet nuclei having an effect up to and beyond 2 m.


  • Transmission modeling of Skagit Valley choir outbreak (53 of 61 participants infected) agreed with the outbreak data pointing towards airborne transmission as the main cause.

  • Transmission modeling of COVID-19 outbreak on the Diamond Princess cruise ship demonstrated the importance of fomites as a mode of transmission and aerosols as a viral source.

  • Elaborating on mitigation, the speaker emphasizes the following measures to mitigate airborne transmission:

    • sufficient and effective ventilation;

    • avoiding air recirculation;

    • particle filtration and air disinfection; and

    • avoiding overcrowding.


  • In a study conducted at Prince Charles Hospital, Brisbane, the infection risk was lower with higher outdoor air changes per hour.

  • A modeling study conducted during COVID-19 pandemic in Italy concluded that assessing the requirement for sufficient ventilation is relatively easy.

  • However, airflow distribution, airflow direction, and fresh air supply could be challenging.

  • The speaker further emphasizes the need for advanced guidelines for building engineering control that would consider the risk of airborne infection transmission.

  • Moreover, the way buildings are designed, equipped, and operated would need a paradigm change to minimize the risk for airborne transmission.


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