Ok folks. Time for some science.
Last week I watched a webinar by a bunch of doctors and it was really informative. I'm gonna take you through some slides.
First up is Tim Cook in Bath. "These are scary times". He advises all doctors to visit this website, has tonnes of useful info. icmanaesthesiacovid-19.org 
This slide is super, super interesting. Tim admits he is not an infectious diseases expert, but that he has been closely following news and studies about the virus since the start of the year. This is his summary deck.
An R0 of 2.5-3, but may be higher.
Ascertainment rate of 12%
2% of *patients* get critically ill.
Attack rate (the number of people who may get infected in the coming months/year) of up to 80%.
But we will come back to this slide.
Ascertainment rate of 12%
2% of *patients* get critically ill.
Attack rate (the number of people who may get infected in the coming months/year) of up to 80%.
But we will come back to this slide.
Tim gave a talk to airways specialists the week before. And on the left you see what his deck was like before, and what it's like last week.
Next Tim turns to these figures from Worldometer.
"These figures look pretty horrific; they look even more horrific if you realise that they you see the acceleration on
the graph on the right. So the doubling time is something like five to seven days it's been outside China"
"These figures look pretty horrific; they look even more horrific if you realise that they you see the acceleration on
the graph on the right. So the doubling time is something like five to seven days it's been outside China"
Next up is the NHS potential surge capacity.
"This is what the epidemic looks like, um that's a very short period of time that that epidemic passes through"
The left line here is where we are (as of last week)
"This is what the epidemic looks like, um that's a very short period of time that that epidemic passes through"
The left line here is where we are (as of last week)
Tim pointing to the bottom of that red curve says. "That's week 20. So this all happens in a period of three months so we have yet to reach the point of acceleration in the UK..."
He continues " when that hits us that will be fairly horrific - this is our the point of the NHS is ability to cope with the
surge. It will be overwhelmed." (Tone is matter of fact here)
surge. It will be overwhelmed." (Tone is matter of fact here)
Tim moves to mortality. "remarkably different mortalities - the problem is that they don't necessarily take account of the ascertainment - that is the number of cases that have been detected or the proportion of cases that have been detected"
This another really helpful slide, the pyramid of mortalities. It explains some of the concepts. "There are undoubtedly a very large number of infections which are not detected as cases and that may be an *eightfold* greater number of "infections" than in our "cases""
"The ratio of real infections to cases is the ascertain rate or the detection rate". The Case Fatality Rate is generally the most important figure.
"...Whereas the infection for the mortality rate is this here but many of these want to simply not be seen." He's saying here that people get the infection, die, but are not necessarily recorded as such. Not surprising during a pandemic.
"We of course in hospitals are interested most predominantly in the severe cases and deaths". Yes, this is where HCWs play their role, saving people.
He notes what we already know. "In the elderly it has a mortality rate of horrific proportions"
Now Tim starts to put some numbers on the pyramid, which is very helpful. But let's go back to the earlier slide first.
"the r0 is that is the number of patients that an index case will infect - so a single infected patient is likely, on average in an uncontrolled situation, to infect roughly two and a half to three individuals"
"...if you compare that to other dangerous illnesses a pandemic flu had a rate of about 1.3. Ebola has a rate of 2. SARS and MERS have r0s which are below this one."
"So flu, with say an r0 of 1.3, if there are 10 cycles of infection that will lead to about 14 people being infected off those ten cycles..."
"... But because if its geometric pattern an
r0 of 3 means that that same 10 cycles leads to 59,000 people being infected. And that's why we have the
problem."
r0 of 3 means that that same 10 cycles leads to 59,000 people being infected. And that's why we have the
problem."
".... the vast majority of these cases are asymptomatic or mild and we probably don't know... but roughly ten fold the ascertained rate - so we'd probably only know about one in eight or one in 10." Tim is saying for every 1 person detected that may be another 8-10 undetected.
"Of the *known* patients roughly one in 8 require hospitalisation... and these patients are very sick, with one in six of those hospitalised patients - maybe higher - becoming critically ill."
"and of the critically ill patients approximately half of them are dying." Here he is talking about patients who may end up in ICU - the most critical cases, as we have seen in Italy.
And referring to the overall CFR - he mentions that it could be between 0.3% and 1%.
"... the incubation period is 7 to 14 days and although we think people are infective for 14 days that can be as long as 30 days. Of great concern." Here he means: once you recover from COVID, you may still be able to infect people for 14-30 days. We're still learning about this
So back to the pyramid. "If you have 100 cases detected... then roughy another 800 are infected". 10 to 15 of those present to hospital, and depending on healthcare
resources and preparedness roughly one to three would die"
resources and preparedness roughly one to three would die"
He then discusses the Chinese CDC study I've mentioned before (it's one of the best so far). and the breakdown of mortalities.
Another key slide. For people who have been hospitalised these are the average timelines.
Onset - admission to hospital - 7 days
Onset - Dyspnoea (shortage of breath) - 8 days.
Onset - ARDS - 9 days
Onset - ICU admission - 10.5 days.
Onset - admission to hospital - 7 days
Onset - Dyspnoea (shortage of breath) - 8 days.
Onset - ARDS - 9 days
Onset - ICU admission - 10.5 days.
On HCWs. China got it down to 8.7% being severe/critical. 5 died. Need more data though.
"I don't know if the numbers are reassuring or horrific." "The ascertainment rate among HCWs is higher than in the general population. If they become ill it's probably that it's detected quite early so the concern is that.. "
... the ascertainment rate is high and therefore that and relatively that that mortality rate is disproportionately high compared to other groups in that paper." Similar story in Italy.
Another very important slide. You don't need me to explain this one.
This means HCWs will be exposed to more virus, since the sickest shed more. Hence the importance of PPE.
There's lots of virus. Tim points to the nasal results in particular.
The virus also hangs around for a long enough time. This is why hand washing is so important - soap works and standard cleaning in the clinical setting kills the virus.
Some guidance on PPE protocols and intubation.
NHS workflow for COVID-19 tracheal intubation.
"... there will be no sidebar help. No - high flow nasal oxygenation or NIV - this is about aerosol generation but also about preservation of oxygen supplies. We can run out of oxygen. Don't use bag-mask ventilation unless you need to - it's aerosol generating..."
(What he's getting at here is you want to minimise the chances of virus getting into the air (aerosol generation) while treating the patient. Otherwise the HCWs might get it)
... but if you do - two people - two handed and the v-grip c.....use your video endoscope first and the vortex if you are in difficulty so that's that's the V grip you got a better grip if you do.. "
Here is the NHS setup.
Flow for CICO, adapted for COVID-19
Tim concludes to fellow HCWs. "Good luck is what I can say. It's going to be pretty tough. Good luck to everybody."
Thread broke, here's the rest
My takeaways.
The reason we're all staying at home: get the rate of infection down fast! Fast!
There may be oxygen supply and PPE supply issues.
Our healthcare workers are working in a higher risk environment. Support them.
Isolate and distancing. Wash your hands.
The reason we're all staying at home: get the rate of infection down fast! Fast!
There may be oxygen supply and PPE supply issues.
Our healthcare workers are working in a higher risk environment. Support them.
Isolate and distancing. Wash your hands.
Thread broke 🙄 more here
