Testing for coronavirus – where have we got to?

Is health secretary Matt Hancock on course to meet his target of 100,000 tests a day by the end of April? He’s only got two more days to get there. The target is his – government colleagues have claimed he set it by himself, and even that he made it up on the spur of the moment. And did he mean 100,000 tests carried out, or just capacity to carry out 100,000 tests? Russell Hall, who also did the chart, and Nick Terdre look into the current state of testing.

If we had an effective vaccine, we could just inoculate everyone and the coronavirus would be under control. But we haven’t, and it might take a long time before we do, so in the meantime testing is at the heart of our efforts to get on top of Covid-19.

Downing Street has played down expectations that it will be clear whether or not the Government has reached its testing target this week. The Prime Minister’s spokesman added: “It’s going to take a little while longer for that to be clear.” He said it will be “difficult” to know on Friday, adding: “For example, home testing kits can take up to 72 hours to get the results for and therefore show up in the numbers.”

The whole testing issue is surrounded by questions, but at least we have a target to focus our minds – after all, there is agreement that widespread testing is a necessary element in combating the coronavirus. At the moment testing is restricted to essential workers and to some extent members of the public displaying CV symptoms.

To get a good grip on the spread of Covid-19 in the population, we need to be able to test much more widely than just people with symptoms. Once we can perform 100,000 tests a day, or 3 million a month, we will actually begin to get a more accurate picture of the extent of infection in the population and be able to make a more reliable estimate of the transmission rate, the average number of people that an infected person themselves infects.

Bringing the rate of infection down to manageable levels is one of the Government’s five conditions for easing the lockdown; another is that the availability of testing is sufficient to meet demand. So widespread testing is a key component in meeting the five conditions.

And that depends on establishing a testing system: having testing kits available, with the teams to perform the tests, having testing locations which people can practically get to, having the lab capacity to analyse the patient samples, with sufficient trained staff, and the logistics to get the samples to the labs and communicate the results back to the patients and forward to the data collection centres. These building blocks are gradually being put in place.

Capacity and performance

What is the current status of testing? On 23 April the government said that testing capacity was up to 51,121 tests a day. Having the capacity is one thing, but using it is another. Latest official data show that capacity is far from being reached, suggesting that all the elements of the system listed above are not yet in place – as of 9am on 27 April, the Department of Health and Social Care and Public Health England reported that on the previous day 37,024 tests had been carried out.

The actual number of people tested was 26,255, as for clinical reasons some people have to be tested more than once. Of that number, 4,310 tested positive, a rate of 16.4%.

Since testing began, a total of 719,910 tests have been carried out on 569,768 people, of which 157,149 proved positive, a rate of 21.8%. So the rate of positive findings is falling, perhaps an indication that as the number tested increases, it is less concentrated on those displaying strong symptoms and proving to have the virus and more on frontline workers in general, including those proving not to be infected.

There will certainly have to be a great leap forward if we are to reach the 100,000 target by Friday, both in capacity and the number of tests performed. But we probably shouldn’t be too concerned about achieving exactly the target exactly on the target day – if we are there or thereabouts, that will represent a vast improvement on, say, 6 April, when only 14,006 tests were carried out.

Infrastructure is being developed

And the infrastructure is being put in place. On 23 April the government announced a big expansion in the availability of testing for essential workers showing symptoms – not just NHS and care staff and other hospital staff such as cleaners, but teachers, public servants, the emergency service workers, supermarket staff, delivery drivers, and other critical infrastructure staff. An online booking system was introduced.

Three mega-labs – the Lighthouse labs – have been opened in Milton Keynes, Glasgow and Alderley Park in Cheshire, each with the capacity to analyse tens of thousands of patient samples a day (government press releases are often rather vague about exact numbers). They are backed by a growing number of drive-in test centres for conducting the tests. A few days ago there were 31 of these, the nearest to Hastings being in Gatwick.

Even if you have a car, that’s still a long drive. If you don’t, you would presumably have to go by train, which apparently care workers are forbidden to do. A solution is offered by the setting up of mobile testing units operated by the armed forces – 96 are due to be deployed in May, visiting care homes, police stations, prisons, benefit centres and fire and rescue services. Although this represents another step forward, in the context of the UK as a whole, 96 such units will probably not be sufficient to provide convenient local test facilities for all.

And the government says these mobile units will also be serving frontline workers, so even with their arrival, we will not yet be testing the general population.

Five-pillar plan

In early April the government announced a plan consisting of five pillars. The first two involve a massive scale-up in swab testing – this is the phase we are still in. The third involves blood tests to check for antibodies -if these are present, they are taken as indicating that the subject has been infected with the virus and got over it, and is therefore immune – though this theory has been challenged.

Yesterday it was reported that scientists working for the government-backed Rapid Testing Consortium have developed a test based on a pin-prick of blood which can be analysed in 20 minutes. If confirmed, the consortium believes it could produce up to a million tests a week by June, representing a real step-change in this form of testing.

The fourth pillar is surveillance – using a high accuracy antibody test to work out what proportion of the population has already had the virus. The fifth pillar is the development of a large-scale diagnostic capacity, which, as noted, is already in place.

Before lockdown restrictions can start to be slowly eased, the number of new daily cases needs to come right down. The government has announced a “test, track and trace” plan to control the number of new infections. This means testing people for coronavirus, tracking the spread of the virus, then tracing the people an infected person has come into contact with. A workforce of some 18,000 people will be required to trace contacts. If someone tests positive, they will then need to isolate for at least seven days, while high-risk contacts could be asked to self-isolate.

Widespread testing is at the core of the “test, track and trace” plan too. So let’s hope that Matt Hancock’s 100,000 target by around the end of this week is reached, and that the testing system continues to be expanded to provide us with a reliable tool, not just for identifying infected individuals, but also for building a dynamic picture of the spread of Covid-19 through the population so that we can formulate the best policies for combating it and eventually returning society and the economy to some degree of normality.

 

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