Trying and Testing Times – attempting to understand what we should be doing

I don’t know about you but I have lost the track and any sense of time …. I’ve just looked at my phone – today is Thursday – lockdown day 9 (counted it on my fingers). Nevertheless, over the last ‘couple’ of days the Daily Briefing, my Twitter feed and the numerous articles I have read have been full of the following words.

‘Test, test, test’, ‘Anti-gen’, Anti-body, ‘PCR machines’, ‘Chemical re-agents’ and ‘Ramping up’

All these words are set against a backdrop of targets, expectations, jargon, obfuscation and a distinct lack of clarity. For me, this is not a time for tribal politics, it is a period where I desperately want to understand the strategy. It is a moment where I want all the ‘experts’ to come together and say ‘yes’ – as a country we are doing what we should be doing.

For me, three issues are dominating the UK’s COVID19 narrative at the moment: the appalling death rate, the lack of PPE for front line staff and testing. This piece focuses on the latter.

If you remember back to the beginning of this pandemic outbreak a ‘few’ weeks ago we were following the so-called ‘mitigation’ strategy. This aimed to slow the spread of COVID19 but not necessarily stop it. It involved testing people who appeared to have contracted the virus to see if they were infected, quarantining them and then attempting to trace and test those who have been in contact with those who had COVID19. This is the test and trace strategy. This is the strategy deployed, it would appear in China and South Korea for example. It enabled China to restrict the spread of the to predominantly one district – Wuhan, in the case of South Korea the epidemic was contained and eradicated in just two out of their 18 regions.

In the UK the mitigation strategy was replaced rather quickly by the ‘suppression’ strategy following the publication of the Imperial College model which stated that unless we shielded the vulnerable, self-isolated, closed schools and universities (i.e. lockdown) at least 250,000 people would die. However, it is now becoming clear that there was another reason that we switched from mitigation to suppression – the UK’s lack of capacity to carry out the requisite number of tests. Johnson at one of the early briefings stated that we were going to ramp up testing from 10,000 a day to 25,000 and then up to 250,000. Days and days later we have barely got about 12,000 tests a day. Indeed, a couple of days ago Gove suggested that one of the problems with testing was a shortage of ‘chemical reagents’, a claim successful be-bunked by ITV’s Robert Peston.

So, the question is, why can Germany test 500,000 people a week and the UK is struggling to carry 100,000 over the same period? If you are interested in a detailed answer to this question, this article by Jack Dickens provides it. In essence in England we have closed regional testing centres over the past decade or so and centralised the process at one location, in mid February the decision was taken to re-open 12 regional centres. England was not prepared for a viral pandemic and as a result we have been caught short when it comes to the capability to carry out the necessary number of tests.

By contrast Germany appears better prepared, it had a plan in place to utilise testing facilities in the public, private and university sectors – thus it is able to test 5x as many people a day compared to England.

It is important to be clear about what the testing is aiming to achieve. What I had written already refers to a test to determine whether you are currently infected – the so-called anti-gen test. Such a test is carried out on a Polymerase Chain Reaction machine or PCR for short and requires specific chemical reagents to test for COVID19, obtained via a nasal swab sample. As I understand it, in England we are using PCR machines in the 12 / 13 Regional NHS testing centres and as a result there is a capacity issue.

Whilst I have never heard of a PCR before, by all accounts it is a standard piece of equipment used in research. Dr. Mark D’Arcy, a microbiologist and university lecturer wrote this on Twitter today ‘I dont understand the delay in testing. PCR is used to test. Every uni in the country, and thousands of biology labs have PCR machines, and ppl who know how to use them. I spent half my PhD running PCR’s. We have the facilities & ppl, we just dont have the organisation.’ The issue is one of a lack of preparedness and a future logistics challenge. I will return to anti-gen testing a little later.

That neatly brings us to the second test, the anti-body test, this is the one that was discussed at one of the daily briefings by the Deputy Chief Medical Officer, Dr Harries, the pin prick blood test, the one we were going to be able to order on Amazon. The anti-gen test will tell you whether you have already had COVID19 and have recovered. Despite what Robert Peston asserted during the Q&A at yesterday’s Daily Briefing this test cannot tell whether you are currently infected. There is a video I watched earlier where a Consultant Epidemologist puts Peston straight on this point and tells him to desist from making such a claim as it was misleading, wrong and dangerous! We have 1 million of these testing kits already (purchased from China) and they are currently being evaluated thus the oft repeated line that we need to be sure they work properly as an inaccurate test is worse than no test.

It seems to me that the anti-body test could bring three benefits (along with some important caveats)

  1. If you knew you had recovered from the disease you could ‘safely’ return to work, useful if you are twiddling your thumbs in lockdown and majorly reassuring if you are a front-line medical employee (caveat to follow)
  2. Getting a community wide perspective on the percentage of the population who have already had COVID19 would help improve the quality of the mathematical models. Have 10% or 60% of the population been infected and have subsequently recovered? It would also provide us with greater clarity on the percentage of asymptomatic COVID19 ‘patients’. Anti-body testing therefore gives the modellers their ‘p’ value and gives some indication of the degree of ‘herd immunity’. (Caveat to follow)
  3. People who have successfully survived a bout of COVID19 (as identified from an anti-body test) have a degree of immunity to the virus. Blood from such people can then be centrifuged, which separates the plamsa from the red blood cells, the plasma can then be transfused in those who suffering from an infection – potential clinical plasma immunotherapy for COVID19. I read that such an approach was being trialled in New York last week and I suspect such an approach is being used in the UK. (Caveat to follow)

And so, to the caveats, there is considerable uncertainty in academic circles about degree of immunity afforded to people who have recovered from COVID19, I have read that there are currently 5 clades (strains?) of the virus and that further mutations are possible. It is currently unclear what the implications of this are. Additionally, it is unclear what the longevity of immunity to coronaviruses is, previous epidemics have found that immunity deteriorates over time. This being a novel coronavirus, the research required to answer these questions is currently being undertaken – work in progress. Finally a single anti-body test on its own will not be enough to determine whether an individual has a continuous high anti-body level and therefore would not identify the best donors for use in plasma immunotherapy treatments. It is because of these caveats and no doubt others, that this pandemic will not be over until an effective vaccine is produced, thus the 12-18 month timeline.

All of which brings us back to the ‘ramping up’ the testing message and the ‘test, test, test’ mantra. Getting the strategy right going forwards will be vital. With regards to the anti-gen test (have you got COVID19 now), this needs to be prioritised now at front-line NHS staff and other key workers (as the Government has stated). Widespread community anti-gen testing at this point will not achieve a great deal, the virus in many areas is now far too widespread to enable a successful ‘test and trace’ strategy.

The implementation of anti-body testing programme, especially if it can be self-administered in the home will provide a lot of useful data and perhaps assist a gradual return to work and potentially help those suffering from COVID19 receive plasma therapy.

We are told that in the next 2-3 weeks the number of new daily cases will plateau and if we stick to the ‘rules’ the number of new cases will then decline exponentially. At this point it is anticipated that the lockdown measures will start to be relaxed. Of course, that will not be the end of the matter, the scientists expect that there will then be another COVID19 viral outbreak later in the year. By then we have all got to hope that the necessary preparations are in place – viz a viz, sorting out the logistics so that widespread anti-gen testing can be carried out – this will surely require expanding the existing NHS capacity by utilising the PCR machines and personnel located in the country’s Universities and ensuring the procedures, personnel and facilities are in place so that we can conduct an effective ‘mitigation’ strategy second time around consisting of an aggressive ‘test and trace’ policy.

I would like to thank Francois Balloux, Professor of the Genetics Institute at UCL , and an expert on viral pandemics, for taking the time to help me to understand the testing issue, via his Twitter feed (@BallouxFrancois).

Finally, I am certain that Government policy consists of, an albeit much more complex version or variant of the above, it would just be useful for them and for us if they clearly articulated their current thinking.

 

 

 

4 thoughts on “Trying and Testing Times – attempting to understand what we should be doing

  1. Thank you. I also saw that excellent article by Jack Dickens. And another on testing,
    ‘Coronavirus: as a health economist, I’m not convinced the case for mass testing stacks up’
    BY CAM DONALDSON
    Which makes the point that inevitably the government policy will be dictated by economics and available resources.

    • To be fair to Hancock – he did the daily briefing today and was I thought very good – there is now a testing plan which whilst hugely ambition sounded credible – best Daily Briefing to date. Thanks for your comment. A

  2. Thanks Adrian.
    We get it! Some countries infrastructure was better suited to the necessary ramping up of testing.
    Test and trace is best. They could see we wouldn’t be able to keep up with that so we went to lock-down to give us time. It slows the peak and hopefully will stop us being overwhelmed meanwhile we are ramping up our testing.
    Remember if we protect everyone we will have poor herd immunity and will pay for it later when there will have been more mutation and the disease may be even worse!
    Lastly (remember the war!) Morale is important and I am very unhappy about the BBCs coverage which seems to undermine confidence in government at every opportunity.

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