The COVID-19 pandemic: Why airborne transmission is importantAug 31, 2020
After a long career, occasionally punctuated by forays into the messy juncture of science and policy, I am increasingly asked about how research and researchers can make a difference. There are institutions that have the purpose of serving as venues for science translation: one key institution in the United States is the National Academies of Sciences, Engineering, and Medicine (NASEM). Chartered in 1863 as the National Academy of Sciences, the current NASEM continues the purpose of providing guidance to the nation on matters of science and policy. Its reports and workshops are wide-ranging, sometimes landmark, and sometimes direction-changing for the nation.
Last week, the NASEM held a two-day workshop on airborne transmission of SARS-CoV-2, a highly controversial topic with critical implications for strategies and policies directed at controlling the pandemic. Leading up to the workshop, there had been sharp debate about the comparative roles of larger "droplets" and of smaller "aerosols". The former are sufficiently large to not travel far, and quickly fall to the ground or land on surfaces while the latter are small enough to stay airborne for hours and move substantial distances, particularly in poorly ventilated indoor spaces. As the COVID-19 pandemic began, remarkably little research had been carried out on airborne transmission of respiratory viruses with much of the evidence related to influenza and SARS (2003).
I chaired the planning committee for the workshop, a product of the Environmental Health Matters Initiative - an activity that extends across the three National Academies. I was joined on the planning committee by faculty-member John Volckens from CSU, and the speakers included Shelly Miller from the Department of Mechanical Engineering, CU Boulder. Over two days, speakers and panelists addressed four key questions:
- What infectious particles do we exhale?
- Does air indoors contain infectious virus and is it present in droplets and aerosols?
- What determines the exposure of people to infectious airborne virus?
- What is the relationship between the load of virus inhaled and risks for infection and for more severe disease?
I understand now why bars may be risky. Loud music and conversation cause people to talk loudly and exhale more virus farther, masks are off to drink, and alcohol consumption probably reduces adherence to distancing - a "perfect storm."
There will be forthcoming brief proceedings and a recording of the meeting will be posted. Additionally, a recording of today's conversation on airborne transmission for the school's weekly COVID-19 series with the Denver Museum of Nature and Science and its Institute for Science and Policy will also be available online.
Changing to another critical topic with regard to the pandemic, trust in the institutions that design and implement evidence-based policies is fundamental to protecting and advancing public health. That trust has been eroded continuously throughout the pandemic in an anchor institution - the Centers for Disease Control and Prevention (CDC) - and now in the Food and Drug Administration (FDA). In its Pledge to the American People, the CDC has scientific integrity and public health ethics as scientific pillars. Recent, unexplained and unjustified vacillation on testing recommendations departed from the agency's pledge. Also troubling was misleading communications by FDA Commissioner Hahn concerning the benefits of plasma therapy for persons with COVID-19. The exaggeration came from confusion of relative and absolute benefits and selective presentation of findings. Trust in these agencies, as for all public health agencies, cannot be lost, particularly as vaccines are rolled out to a public that includes many who are leery of vaccines.
And, the fall academic year has started. Welcome to the new and returning students. This will be a different but great year.
Keep on wearing your mask!