We speak with Prof. Donald Milton, Professor of Environmental Health, Applied Environmental Health (MIAEH), about the differences between SARS-CoV-1 and SARS-CoV-2.
Taking the precautionary principle in medicine into consideration, in your opinion why does the WHO insist on its statement regarding the transmission competence of SARS-CoV-2? Do you envisage a different (international) governmental approach soon?
Donald Milton: I think that the WHO position articulated on 27 March 2020 saying that aerosol transmission is not possible is driven by two things.
First, epidemiology is not capable of distinguishing among contact, droplet, and airborne transmission and there is a strong bias in the medical infectious disease professions towards acknowledging only those transmission pathways wherein the agent can be easily detected in the vehicle of transmission. It is relatively easy to detect an infectious agent on surfaces and in large droplet spray. The aerobiological pathway is elusive; it is very hard to detect even Mycobacterium tuberculosis in the air, even though we know that it is transmitted by exhaled aerosols.
Second, the ability to provide healthcare workers with protection from airborne infection transmission via aerosols is very limited. It is especially so in low- and middle-income countries, but also many wealthy countries have not prepared and are confronting extreme shortages. I think that there is a lot of fear about consequences if workers are told that they cannot be assured of effective engineering controls and proper personal protective equipment.
Given that there are now several reports of the presence of SARS-CoV-2 in respirable aerosols and on exhaust vents indicating potential airborne infection risk, the precautionary principle mandates that we consider that risk as real and take all possible steps to limit that risk.
We have evidence of the aerosol and surface stability of the SARS-CoV2, however, we don’t know its exact transmission competence. In your opinion, why haven’t further studies on the aerosol/airborne transmission competence of SARS-CoV-2 taken place yet, if the WHO considers airborne transmission in specific circumstances possible?
Donald Milton: The needed studies are hard to do, require significant planning to keep study personnel safe, and funding is urgently needed. I myself have submitted multiple proposals to fund work using a bioaerosol collecting device, the Gesundheit-II to try and answer this question. I’m hoping that we will receive funding soon.
What do you identify as the biggest and most challenging difference between SARS-CoV-1 and SARS-CoV-2?
Donald Milton: SARS-CoV-2 is much more capable of human-to-human transmission.
In your opinion what is the biggest mistake regarding how the current pandemic is handled on the international level and why?
Donald Milton: Pandemic planning and preparedness were clearly not where they needed to be in many countries and on a global scale. Stockpiles of emergency supplies need to be maintained. I’m sure that there are many lessons to be learned both locally and globally.
