Covid_19

by

Dancing Out of Lock Down – A Slowy

How do we get out of lockdown? Clearly the government are wrestling with the issue as we speak. They don’t want to share their thinking as they’re afraid the great British public are incapable of holding two ideas in their mind at the same time. Clearly, the government can draw on the advice of all manner of highly qualified professional advisors. And it is certain that whatever strategy eventually emerges will be guided by “the science”.

In what follows I attempt to think through some of the issues from a lay persons point of view. This is not to second guess what “the science” will show but to be able to ask sensible questions of the science when it emerges.

Some of the most consistently informative and convincing material I have read about Covid-19 has been that produced by Tomas Pueyo whose characterisation of the progression of the disease is particularly persuasive. He identifies basically two phases which he labels The Hammer and The Dance, illustrated below. In essence the Hammer is getting a grip of the disease and suppressing the spread.  This is done through strict social distancing and lockdown. The Dance is where the lower rate of infection is maintained by retaining social distancing after lockdown but supplementing this with testing, tracing and isolation.

This process is inevitable in the absence of either a vaccine, a cure or herd immunity. All the evidence seems to be that the first two are unlikley to be available for some 12 to 18 months. This leaves herd immunity. However there are a series of problems with this.

First, it is not clear that individuals develop natural immunity. Second, even if we assume natural immunity is secured by infection and recovery then in a UK population of 66m people we need 39m to have contracted and survived the disease to get to the 60% personal immunity level needed for herd immunity.

How close are we to this number? In the absence of mass testing we can only guess at the number already infected.  If we assume that the mortality rate is 1% of those infected as of when I started writing this (Saturday 18 April) the number of those that have died in the UK is reported as 15,464. This would suggest just over 1.5m people have the disease. [Warning this is uninformed common sense and may be something an epidemiologist would laugh at.] Logic says we therefore need another 27.5m to get infected and survive.

This brings us to the third problem, which is the cost in lives of securing herd immunity. In the absence of any treatment reducing the mortality rate, in order to get to herd immunity we might expect the ultimate death toll to be in excess of 390k people (1% of 39m). Without breaking the link between infection and mortality rate via a vaccine or cure these numbers look logical but unacceptable.

This would suggest a strategy is needed which buys us time. In other words reduces the number of deaths until a vaccine or cure is found. This can be done by: a) minimising the overall infection rate, the infamous “R” and; b) reducing the “R” even lower amongst the most vulnerable population. The initiatives to date by the government can be said to have been successful id a little late at dealing with a), however the picture on b) is rather mixed. The proposal that those who are particularly vulnerable should shelter at home makes sense to achieve b) however allowing the disease to get hold in care homes is the exact opposite.

So coming out of lock down what does the government need to do? It has set out a 5 point plan:

  1. Protect the NHS ability to provide sufficient critical care and specialist treatment across the UK;
  2. Need a sustained and consistent decline in the daily death rate;
  3. Reliable data that the infection rate or “R” is down to manageable levels across the board;
  4. Confident operational challenges, specifically testing and PPE are in hand;
  5. Confident no proposed change will risk a second peak in infection that overwhelms the NHS.

At the moment evidence seems to be building that the first three of Dominic Raab’s five tests for the movement out of lockdown will soon be met.

Test 1 is clearly a minimum requirement. Demand must be brought down to well within the capacity of the equipped and staffed ICU beds in the UK. Clearly the current level of demand is far too high. Demand needs to be reduced to a level which can accommodate spikes in demand, and the need to restart elective surgery and urgent cancer treatments. It also has to be at a level which does not put such an intolerable strain on front line staff.

However once you have got the disease down to a manageable level you need to turn to Mr Raab’s last two tests. These look sensible but rather problematic.

PPE remains a mess with the scale of the problem reducing the further away you get from the front line. It remains the case that for significant numbers of nurses, doctors and carers the lack of supply of PPE is an existential fear. Senior management, on the other hand, is confident there is sufficient PPE, although they are happy to change the guidelines on what PPE is appropriate mid-crisis, and not in a more stringent direction.

Which brings us to testing. Testing is the music needed for the Dance.

Matt Hancock has committed to achieving 100k tests per day by the end of April. At the moment the number of tests actually being done per day is around 20k. Matt Hancock says “Ahh yes, but there is capacity for 40k”. Unfortunately success is not measured by capacity but by results. I could have run a lot faster but I didn’t. Capacity is a necessary precondition of results but it is not sufficient. If we had infinite capacity to test everyone in Wick it would not be that much help. But put that aside.

Are 100k, actually completed, tests per day enough? It turns out they may be just about there if estimates of the level of testing needed to effectively monitor the disease post lockdown in the US, by the Harvard Global Health Institute, are correct. They suggest that a testing rate of a minimum of 152 tests per 100k population are needed to effectively monitor and manage the disease. Such a level should enable those showing any signs of disease, even mild flu like symptoms, to be tested in the community plus an average of 10 contacts.

Given a population of 66m divided by 100,000 gives you 660, multiplied by 152 = 100,320 tests per day required in the UK. Clearly there may be demographic or geographic or cultural drivers that move these numbers a bit but you would have thought they were in the right ballpark

So in order to go to the Dance without risking a second, unmanageable wave of infection, we need in place an infrastructure to enable a minimum of 100k tests per day to be carried out, all the contacts of those testing positive to be traced and all those infected isolated. A lot to put in place in less than three weeks.

Trying to draw some conclusions from all this.

First, what may delay coming out of lockdown is not the reduction in death rates etc it may be more about the materials and logistics for managing the virus after the end of lockdown.

Second, the end of lockdown is not the status quo ante. Far from. Our social, cultural and economic lives will continue to be severely constrained for some 12 to 24 months after the end of lockdown.

Third, this has specific economic consequences. Turning the economy off is a lot more straightforward than turning it back on. If the government does not continue to provide support to businesses in what might be a very long transition phase. more businesses could go bust coming out of lockdown than did going in.

Third, vulnerable groups are likely in for a particularly tough time. The reality may be they need to “shelter” until there is a vaccine. If this is the proposal from government it is not acceptable. They need to apply their minds to drive “the science” to come up with some way in which the vulnerable can get out of their homes, particularly those that live alone. Some creative thinking on this should be happening now and by pressure groups for the elderly and sick not just the scientists.

As Churchill might have put it coming out of lockdown is not the end, it’s not even the beginning of the end, it may however be the end of the beginning.

 

 

 

 

 

 

 

 

 

by

Masking the Future

The issue of the beneficial effect of face masks is much in the news at the moment. Whenever you hear people clarifying the position on masks you come away slightly more confused than when you started. The “science” has moved from, they have no beneficial effects, to they don’t stop you catching Covid-19 but they may reduce substantially the chance of you spreading it if you have caught it.

But even the latter “science” is followed by advice that the general public should still not use masks. Why? Accepting that the mask does not stop you getting the disease, surely if it reduces substantially your chance of spreading Covid-19 it is worth people wearing masks. I thought the whole point was to break the chain of infection and surely it does not matter whether it is the getting or the giving which breaks the chain.

Usually, when the discussion has got to this point the government spokesperson talks about the mask becoming a source of infection if you do not take it off properly or dispose of it properly. However, I guess if the mask is infected that is because it has stopped something that would otherwise be infecting your face.

The next argument is masks promote a misplaced feeling of security and undermines the commitment to social distancing and hand washing. I suspect the contrary is true and that the face mask is a constant reminder of the risk of infection. However, that is just a hunch based on observing those with masks who seem, at least to me, to be more conscious of strict social distancing than those without. Of course that is just anecdotal, but I suspect it is the same evidence base as the “undermining commitment” theory.

Finally, they point to the advice of the World Health Organisation. That is definitely worth a look. There is a very interesting vides explaining “When to use a mask.” The video like much of the communication on Covid-19 requires close attention. 

It starts with a very clear statement that masks cannot protect against Covid-19 but then qualifies this with “when used alone”. It goes on to say you need to combine with hand washing and social distancing. Which sort of suggests it does have some benefit. This seems to be clarified when it goes on to say that WHO only recommend you wear a mask if you have symptoms of Covid-19. This would seem to support the prevention of spreading theory. The “giving” bit of the chain.

But then it goes on and says “There is no evidence that they (masks) protect people who are not sick” A very clear statement on the lack of prophylactic benefit. But the very next sentence says “However, if you are healthy but you are taking care of a person who [may be infected] then you should wear a mask whenever you are in the same room as that person.”

So wearing masks does not prevent you from getting the disease from an infected person however if you are with such a person you should wear a mask. All clear?

I suppose you might say this is an example of the “precautionary principle”, i.e. we have no evidence that it works but we have no evidence that it does not work either so what’s the harm in wearing it. Or that the virus is more/less virulent inside than outside and therefore the advice differs by location.

What comes across from this advice and much of the information that comes out of the UK press briefings is the need to listen very carefully to every word. The statements made are very carefully crafted to enable alternative interpretations to be put on them. 

I have no idea why the Government has taken such a clear position on face masks for the general public. My suspicion is that in a situation where front line health and care staff cannot get the PPE they need the Government don’t want any calls on supply or production that might divert the short supply that exists from them.

That is a perfectly reasonable position that I am confident the vast majority of the public would respect. I am pretty confident once supply issues are no longer a constraint the “science” on masks will change. We may then get advice on the matter which does not sound like a G7 communique that has been all night in the negotiation and which says – black is white except in circumstances where it is white.Masking the future