This week’s blog is written by Dr Evonne Curran (@evonnetcurran).
In the Danish Museum at Roskilde there are the remains of 5 Viking boats which were deliberately sunk c1072, to facilitate the control of the waterways. The boats were rediscovered in the 1960s and originally known as the ‘Roskilde 6’. However, boat 4 never existed. What was thought to be boat 4 was in fact part of a very long boat 2. Yet ‘Roskilde 6’ continued to be the title used in reports for many years. So, an original interpretation based on insufficient information of remaining planks of wood was wrong. Further excavations provided evidence of the error. No harm was done in this erroneous misinterpretation of initial evidence. Vikings were not about to say, ‘Oh no we didn’t’. Archaeologists’ reputations were left intact with something like ‘…preliminary results suggested, but…’. Reinterpretation of historic events improves our understanding – but has no implications for health. Not so with the interpretation of evidence before and during the pandemic.
The pandemic’s boat 4 – droplets
In 2007 the Centres for Disease Control (CDC) produced isolation guidance for hospitals – in which respiratory infections were described as being either spread by droplets (sprayed on) or aerosols (inhaled/airborne). Of note, the description as to how droplets enter to cause infection is made without supporting citation (their p18).
UK guidance (2013) on respiratory transmission/protection used the CDC guidance with an assessment of the evidence strength as ‘generally accepted’. Ergo, we entered the pandemic with respiratory modes of transmission that were ‘generally accepted’ rather than strongly evidenced-based. The question therefore is why was this ‘boat 4’ of droplets being the main mode of respiratory transmission, held to be true with such gusto in the presence of such little evidence?
At every level of Infection Prevention and Control (IPC) above that of a hospital team, those charged with writing guidance to protect healthcare workers (HCWs), generated errors in reviewing, interpreting, and correcting. These collective errors have made the advocacy of others outside the system – regardless of the strength of their evidence – hit the proverbial brick wall. Of note, every health service disaster has started with someone presenting someone else with data, and the person presenting the data as well as the data itself being ignored. This is irony indeed as IPC is forever illustrating how people ignored Semmelweis’s hand hygiene data.
Below are examples of the errors for the pandemic’s boat 4 – droplets.
World Health Organization (WHO)
The WHO’s initial assessment that COVID-19 was spread via droplets consists of evidence that transmission happened close to a source – not that it was spread via droplets.
After 25 months of reviewing the transmission literature on SARS-CoV-2, this body concluded that transmission occurred via ‘close contact’ – something that was known in 2020. There was insufficient evidence they felt to conclude airborne was occurring and presumably therefore a need for the precautionary principle to protect against it.
Covid Nosocomial Review Group:
When asked by the CNO to explain why researchers found coughing produced more aerosols than AGPs, they minuted this ‘Ah, but’ response.
“CNRG highlighted that WHO recommend that medical/care procedures should be assessed based not only on their capacity to generate aerosols but also on their ability to generate infectious aerosols and an association with relevant transmission events.”
However, what determines if aerosols are infectious is whether the patient is infectious.
The UK guidance stopped providing evidenced explanations as to how SARS-CoV-2 was being transmitted and merely stated that droplet precautions were required to defend against it.
Infection Prevention Society/Hospital Infection Society: T
his multiple learned society guidance after extensive review of 4 outbreaks (one of which was on a plane where no transmission happened [their ref 82]) determined that droplet transmission was probable and airborne transmission was possible (when performing AGPs). I invite and encourage the rewriting of this guidance, as there was an absence of definitions for both droplets and aerosols.
At a time when people want to forget the pandemic, many HCWs who care for people infectious with COVID still await adequate respiratory protection equipment (RPE) for an airborne infection. The erroneous interpretations of science have, and continue, to cause harm. I have no understanding as to why the organisations charged with producing guidance failed to recommend RPE, especially given the paucity of evidence to support their claims, e.g., droplet only respiratory transmission cannot be evidenced.
The recent Lancet paper on pandemic errors cites as no 2 the delay in the WHO recognising that SARS-CoV-2 is airborne. ECDC recognises airborne transmission, leaving the UK almost alone in Europe in failing to acknowledge that SARS-CoV-2 is airborne. The droplet paradigm will eventually, like ‘boat 4’ be consigned to history – but not just yet in the UK it seems. However, I and many others will not stop trying to expedite this.
Evonne T Curran @evonnetcurran
Is a Doctor of Nursing and has worked in the field of Infection Prevention & Control since 1988.
She has been working independently since 2015 but led the Outbreak Programme of Work at Health Protection Scotland for many years.
Her retirement has been postponed working on providing HCWs with RPE and getting the UK to acknowledge that for which there is overwhelming evidence. SARS-CoV-2 is airborne.
2 thoughts on “Erroneous assumptions – it’s droplets…”
Great analogy Evonne.
We need to sink ‘boat 4’ (aka ‘extended boat 2’) misconceptions once and for all.
In the context of ‘droplets’ this feeble excuse for science has most likely killed more people (HCWs) than the original Viking occupants of ‘boat 4’ could ever have imagined or hoped for.
Whilst the original ‘boat 4′ archeologists’ reputations were left intact, no such luxury should be afforded to the modern day architects of the fateful IPC policy who have used “droplets not aerosols” as a despicable excuse to deny Health and Social Care Workers the Respiratory Protective Equipment needed to keep them safe during the past, current and maybe future waves of the pandemic.
Fantastic work someone will need to be held accountable