The false narratives of SARS-COV-2 transmission have compromised healthcare worker safety
By Dr Raina MacIntyre
The initial proclamation that SARS-COV-2 was transmitted by droplets and contact was made by the World Health Organization early in the pandemic, without supporting scientific evidence, and at a time when scientific knowledge about the virus was minimal. In one sweep they set the stage for countries everywhere to shift responsibility for healthcare worker safety and simply cite the WHO as the most authoritative source of evidence. In Australia, experts say airborne transmission is minimal, and providing health workers with airborne precautions may even be dangerous and create a false sense of security.
Droplet or airborne – a false paradigm
The droplet vs. airborne paradigm has driven hospital infection control policy for almost a century, but is based on very old data which has since been disproven. It originates from photographic techniques from the 1930s and 40s which suggested large droplets are expelled within 2m of a patient and fall to the ground rapidly, whereas smaller airborne droplets may exist beyond 2m, for longer periods of time, and that these two modes are mutually exclusive. In fact, droplets of all sizes exist in a continuum, and large droplets can travel further than 2m. Yet this 2m rule defines the safe spatial separation of a patient from a health worker, and informs how health worker risk is determined in the workplace. In Victoria, there are over 1000 active HCW infections, and the vast majority are alleged to have caught it in the community. We do not know who exactly attributes the source of infection in Victorian health workers, or how this is done, as none of this data is transparent. It appears that the false 2m rule has defined which health workers are “counted” as being exposed in the workplace. What if only the nurse who was within 2m of the COVID-19 patient is counted as having caught it work, but the infected ward clerk who sits at the nurse’s station of the COVID-19 ward 4m away from the patient is not counted as a workplace infection? This then serves to reinforce a confirmation bias for the unscientific belief that infection is only possible within 2m of a patient.
Why the narrative of community acquisition of HCW infections does not stack up
My back of the envelope calculations of risk for health workers versus the rest of the community tell another story. Using available data on healthcare worker infections and infections in the community, as a well as AHPRA registered health workers in Victoria and the Victorian population as denominators, shows that overall, health workers have a risk of COVID-19 infection that is 3.4 times higher than the general community. What if we only looked at the small proportion of health workers (<20%) attributed to workplace infection? Well, they seem to have a 32% lower risk of infection than the general community. Sounds like the hospital is the safest place to be if you want to avoid catching COVID-19! And what about the other health workers who are said to have caught it in the community? My calculations show they are 2.8 times more likely to be infected than everyone else in the community, even though they all “caught it in the community”. How is that even possible, unless health workers are secretly having COVID parties outside work to intentionally infect themselves? It just doesn’t pass the “pub test” and suggests that confirmation bias is operating, with a narrative to attribute health worker infections to anywhere but the workplace.
The shifting goalposts for proving airborne transmission
The other key issue is spread of SARS-COV-2 by airborne or aerosol transmission, which was initially denied by the WHO. When evidence started building that viral RNA could be found in air samples in the hospital ward, the goal posts shifted to denying the infectious potential reflected by viral RNA. At the same time, studies found widespread surface contamination of hospital wards with SARS-COV-2, but this was accepted as evidence supporting contact transmission. It seems viral RNA only signals potential infection risk when found on surfaces, but not when found in the air. We continued to be told that handwashing or social distancing will fix the pandemic, while mask use was downplayed and delayed until catastrophic epidemics that could not be controlled by handwashing and distancing alone started occurring in places like New York. The CDC endorsed community mask wearing on April 3, two days after the National Academies of Sciences, Medicine and Engineering wrote to the White House about concerns regarding airborne spread of SARS-CoV-2. The WHO endorsed community mask wearing in June. Why was this simple and effective intervention delayed for so long?
Then evidence started accruing that viable virus, not just viral RNA can be found in the air, and the goal posts shifted yet again to denying the significance of this finding and questioning the infectious dose of virus in the air required to infect people. Ironically, the unproven assertion that SARS-COV-2 is spread by droplets and contact is not subject to the same burden of proof that airborne transmission has been subjected to. However, in July, after being challenged about airborne transmission by over 200 scientists, the WHO conceded that airborne transmission could not be ruled out in indoor settings. Well, hospitals are indoor settings with likely high viral load on COVID-19 wards due to compromised hazard control measures.
Enter the R0 into the debate
By August, a new narrative was created of “evidence” to support droplet transmission, central to which is the R0 (R “naught”) or basic reproductive number. Most estimates find the R0 for SARS-CoV-2 to be 2.5-3, but as high as 6 in New York State and Wuhan. This is used as “evidence” that SARS-CoV-2 is not airborne because its R0 is much lower than an airborne virus like measles which has a R0 of 12-18. However arguments like this fail to account for other airborne viruses like varicella (which causes chicken pox) that has also been responsible for hospital outbreaks via airborne spread but has a R0 of 4-5, similar to SARS-CoV-2.
Invoking the R0 is a distraction from the science before us. The R0 has never before been a criterion for defining the mode of transmission – in fact, tuberculosis, which is accepted as airborne, has a R0 which is much lower, being <1 in developed countries, than that of SARS-COV-2. Influenza, too, which is proven repeatedly to be airborne, has a lower R0 and we are still told it is a droplet infection. Pertussis is more infectious than varicella and almost as infectious as measles, with a R0 of around 16, but we are told it is droplet transmitted. Finally, given that over 80% of SARS-Cov-2 cases are mild, and there is substantial asymptomatic infection, the official case counts upon which the R0 is calculated are likely to be vastly under-estimated, and the true R0 is likely higher. If the R0 of SARS-CoV-2 is so low and inconsequential, why is the virus spreading out of control and causing catastrophe around the world?
The use of R0 to bolster a failing and implausible argument about transmission of SARS-COV-2 is disingenuous at worst and ignorant at best. R0 is a function of the pathogen, the host and the environment, and varies for any given pathogen by factors such as population density and environment. So, the R0 for measles is different in a big city compared to a small town. It is not a measure of transmission mode.
According to the detractors of airborne transmission, droplet transmission can be proven by the R0 and nothing else, but airborne transmission cannot be proven by finding virus in the air hours after it is aerosolised. At every turn, the evidence is explained away to prop up an argument which is past its use-by date.
Finally, the idea that guidelines should only be driven by transmission mode is misinformed. Transmission mode is only one consideration in PPE guidelines, the others being occupational health and safety obligations, availability of drugs and vaccines, severity of the disease and scientific uncertainty. Here we are repeating the mistakes of SARS in Toronto 2003, all over again while the toll of healthcare worker illness climbs. Without proven drugs or vaccines, the precautionary principle should be used to protect healthcare workers from a serious infection such as COVID-19. HCWs like everyone else are immunologically naïve to this virus but at least 3-4 times at higher risk of infection. The continued denial of scientific evidence of airborne transmission, and shifting goal posts as the evidence accrues, reflects a dogged determination to entrench a position based more on an ideology than science. In the midst of the worst pandemic of our lifetimes, we cannot afford to indulge the reasons for this ideology. Continuing to defend or excuse this ideology imperils the lives of healthcare workers, and distracts from the urgent task of keeping them safe at work.