Series by Dr Evonne T Curran – All About Long Covid

The 4th Mode of Nosocomial Transmission – Airborne Dissemination

This week’s blog is 6th in a series by Dr Evonne T Curran (@EvonneTCurran).

The pre-pandemic Infection Prevention and Control (IPC) model for respiratory transmission (droplets or aerosols) with droplets being the dominant mode is un-evidenced. Although this has yet to be admitted by some guidance writers – the evidence for airborne infection is overwhelming. Much of what I have been trying to do is persuade people that most respiratory infections including SARS-CoV-2 are airborne. I naively thought that if the new paradigm was accepted (everything ≤100μ being inhalable), this would naturally lead to the correction of control measures and the introduction of indoor air quality and respirators. This is yet to happen.

However, the further I investigated the existing 3 Modes of Nosocomial Transmission (MoNT), and the 3 corresponding precautions (airborne, droplet, contact), the more I realised that these modes of transmission omit another MoNT altogether – Airborne Dissemination. Having been ignored when demonstrating that the droplet or airborne paradigm needs amending, perhaps this argument – you have omitted a 4^th MoNT altogether – might yield better results.

“If you don’t tell people the truth about COVID, how can you expect people to make good judgements about risk.” Kernow Jones

This week’s blog is by Dr Evonne T Curran (@EvonneTCurran).

For me this pandemic is a simple ‘consequent argument’ (if P then Q), i.e., if airborne transmission is evident, then recommend airborne precautions. The challenge is that this argument is not universally accepted even though airborne transmission is considered the main route in this UK government document on ventilation. However, the importance of this argument has begun to seem moot in the eyes of many, as precautions have been lifted, personal experience of COVID, is ‘it’s not that bad’, and the government’s position of ‘let it rip’ has not killed anyone they know (yet). So, this blog must show that the ‘consequent’ argument’ is still worth fighting for. Which brings us to the above quote – what is the ‘current truth’ about COVID?

Part 2 – Prove to me it’s airborne – well it’s the aerosol scientists that have done that…

This week’s blog is by Evonne T Curran (@EvonneTCurran) and is the second in a series exploring the evidence that covid is airborne.

It’s not droplets (Part 1) showed that neither the WHO nor the CDC provided evidence for the ‘droplet only transmission route’. Before we explore airborne, it’s worth questioning why people were reporting ‘droplets’ in papers and guidelines. If you believe ‘close = droplets’, you will see droplets, you will report droplets and you will take comfort from everyone else seeing and reporting them also. Textbooks will confirm droplets (without presenting direct evidence for ‘droplets’).

So, was the reporting of droplets in the infection prevention and control literature, a case of belief in an unproven maxim? Well this report of influenza transmission shows that it can happen. It includes a re-evaluation of outbreak reports looking for whether the original authors had evidence to exclude any Mode of Transmission (MoT). The re-examination identified that in several reports, airborne transmission had been eliminated without evidence (Table 2 p40). Thus, a Sherlock Holmes MoT exclusion approach must be applied when outbreak reports state transmission is by a particular route, when they have failed to exclude other routes.

Patient Healthcare Worker and Visitor Safety during an outbreak (and a begging bowl)

This week’s blog is by Dr Evonne T Curran (@EvonneTCurran).

Managing an outbreak starts with data, (e.g., surveillance data: a rise in the number of x, clinical data: someone calls saying “we have 4 people with diarrhoea and vomiting”, or laboratory staff identify alert organisms). You then decide whether you can exclude an outbreak. If you can’t exclude – you immediately act. The first act is to put in place everything needed for Patient, Healthcare Worker (HCW) and Visitor (PHV) safety. For example, you might close a bay or a ward (norovirus), stop showers (Legionnaires disease), or isolate cases (infected wounds). You don’t wait for a committee – this is ‘first aid’ for PHV safety. Then you investigate. The investigations may identify the need for more control measures. Control measure implementation assurance checks are made, and the epidemic curve is monitored. This is the daily graph of new cases. If all necessary control measures are being followed, after a lag for the incubation period, the epidemic curve will fall as no new people are being exposed. If cases continue to arise, there must be an omission of one or more control measures indicating further investigations and control measures are needed. This process continues until the outbreak ceases.

Erroneous assumptions – it’s droplets…

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.