Coronavirus UK: Current antibody test kits ‘only 50% accurate’

By | April 27, 2020

Blow to getting Britain back to work after Oxford scientist tasked with evaluating crucial coronavirus antibody tests says it may take a MONTH before one is ready for Britain to use as another expert warns the kits may only be 50% accurate

  • Government has reportedly ordered over a million tests that are no good 
  • Antibody tests, which show who has already had the virus, are vital for the UK 
  • But England testing chief says they aren’t sensitive enough for mildly ill patients
  • Officials are now working with manufacturers to help them improve products 
  • Here’s how to help people impacted by Covid-19

Professor Sir John Bell, from the University of Oxford, said officials are struggling to find a good quality antibody test

Professor Sir John Bell, from the University of Oxford, said officials are struggling to find a good quality antibody test

Britain’s hopes of going back to normal today suffered another blow after a top scientist checking coronavirus antibody tests for the Government said none of the ones he’s seen so far are any good.

Professor Sir John Bell, from Oxford University, said the testing kits he has examined so far ‘have not performed well’ and ‘none of them would meet the criteria for a good test’. 

Dashing hopes of lockdown ending any time soon, Sir John said it would take ‘at least a month’ before antibody tests, which tell whether someone has already recovered from COVID-19, would be available for the public. 

He said: ‘We see many false negatives… and we also see false positives. This is not a good result or test suppliers or for us.’

Downing Street said today it will seek refunds from companies that cannot improve the failed antibody tests ordered by the Government.

‘No test so far has proved to be good enough to use,’ the PM’s official spokesman said, raising accuracy concerns.

‘We continue to work with the testing companies, we’re in a constant dialogue with them and we give feedback to them when their products fail to meet the required standards.

‘If the tests don’t work then the orders that we placed will be cancelled and wherever possible we will recover the costs.’

Sir John’s comments come after the head of testing at Public Health England also said none of the tests it had evaluated were good enough for public use.  

Professor John Newton, director of health improvement at Public Health England, said the tests were not accurate enough on people who had only had mild illnesses.

The tests are considered to be crucial to ending Britain’s nationwide lockdown because they will give authorities a clear picture of how many people have caught the virus already and shaken it off. 

Currently, statistical guesswork is the only way of working out how many people might already be immune and therefore potentially safe to return to normal life.

Estimates suggest up to five million people could have been infected to date.

Professor Newton’s comments come after one expert in New York said people who catch the virus but don’t get seriously ill appear not to be making many antibodies, making it hard to test them. For this reason, he suggested, even good tests might only be 50-60 per cent accurate.   

Sir John Bell added that other countries have had to send back failed tests and that it is possible that some unreliable tests could have false positive results triggered by other viruses which produce similar antibodies to COVID-19.  

Public Health England has refused to reveal what the Government considers an acceptable level of accuracy. 

The US last week launched its first antibody test after a firm in North Carolina got approval from the Food & Drug Administration (FDA). It is claimed to be 93.8 per cent accurate.

Professor John Newton, chief of COVID-19 testing for Public Health England, said none of the tests examined so far were accurate enough to roll out across the UK

Professor John Newton, chief of COVID-19 testing for Public Health England, said none of the tests examined so far were accurate enough to roll out across the UK

In his blog post, published on the University of Oxford’s website yesterday, Sir John, a royally-appointed medicine professor at the university, said the UK was not the only country struggling to find reliable tests.

He wrote: ‘The Spanish apparently returned test kits that were not working, and the Germans who are developing their own sensitive kits believe they are three months away from getting these available and validated.’ 

Explaining the difficulties, he added: ‘To validate these tests you need a gold standard test so you know the correct answer and you need [blood] from patients who have recovered from the virus infection they had approximately 28 days before. 

WHAT IS AN ANTIBODY TEST?

An antibody test is one which tests whether someone’s immune system is equipped to fight a specific disease or infection.

When someone gets infected with a virus their immune system must work out how to fight it off and produce substances called antibodies.

These are extremely specific and are usually only able to tackle one strain of one virus. They are produced in a way which makes them able to latch onto that specific virus and destroy it.

For example, if someone catches COVID-19, they will develop COVID-19 antibodies for their body to use to fight it off.

The body then stores versions of these antibodies in the immune system so that if it comes into contact with that same virus again it will be able to fight it off straight away and probably avoid someone feeling any symptoms at all.

To test for these antibodies, medics or scientists can take a fluid sample from someone – usually blood – and mix it with part of the virus to see if there is a reaction between the two.

If there is a reaction, it means someone has the antibodies and their body knows how to fight off the infection – they are immune. If there is no reaction it means they have not had it yet.

‘You also need blood from people who donated before the epidemic so you know whether you falsely see positive tests when there is no Covid-19 in the sample.  

‘For example, there are a number of other coronaviruses circulating that might stimulate antibodies that cross react to Covid-19 proteins. 

‘It has taken some time to gather these tools for validation but the UK is now uniquely positioned to evaluate and find the optimal test for this disease. 

‘We clearly want to avoid telling people they are immune when they are not, and we want all people who are immune to know accurately so they can get back to work.’ 

And a boss at PHE, Professor Newton, told The Times that the antibody tests bought by the Government so far were ‘not good enough to be worth rolling out’.

Health Secretary Matt Hancock last week claimed that 3.5million of the tests had been bought but admitted officials couldn’t confirm that they were any good.  

The Department of Health later rowed back and said it hadn’t actually bought the tests yet, just put an agreement in place to do so if they were up to scratch. 

 In a statement the Department said it had ‘secured small numbers with potential to get much larger orders,’ The Telegraph reported. 

HOW ACCURATE DO ANTIBODY TESTS ON THE MARKET CLAIM TO BE? 

Cellex qSARS-CoV-2 IgG/IgM

COUNTRIES APPROVED IN: US and Australia 

MANUFACTURER: Cellex Inc, North Carolina 

ACCURACY: 93.8% true positive, 96% true negative 

2019-n-CoV IgG/IgM Rapid Test Cassette

COUNTRIES APPROVED IN: Australia 

MANUFACTURER: Hangzhou Alltest Biotech Co Ltd (China)

ACCURACY: Company claims up to 98.6 per cent  

COVID-19 IgG/IgM Rapid Test Cassette

COUNTRIES APPROVED IN: Australia

MANUFACTURER: Zhejiang Orient Gene Biotech Co Ltd (China) 

ACCURACY: 87.9-97.2% true positive, 100% true negative 

OnSite COVID-19 IgG/IgM Rapid Test

COUNTRIES: Australia

MANUFACTURER: CTK Biotech Inc (USA)

ACCURACY: 96.9% true positive, 99.4% true negative  

SARS-CoV-2 Antibody Test (Lateral Flow Method)

COUNTRIES: Australia, China 

MANUFACTURER: Guangzhou Wondfo Biotech Co Ltd (China) 

ACCURACY: Unknown 

SARS-CoV-2 IgM/IgG Antibody Rapid Test

COUNTRIES: Australia, China 

MANUFACTURER: Hightop Biotech Co Ltd (China)

ACCURACY: 82-93% true positive, 97% true negative  

VivaDiag™ COVID-19 IgM/IgG Rapid Test

COUNTRIES: Australia, Singapore

MANUFACTURER: VivaChek Biotech (China)

ACCURACY: 81.25-97.1% true positive  

Biolidics 2019-nCoV IgG/IgM Detection Kit

COUNTRIES: Singapore

MANUFACTURER: Biolidics Limited (Singapore)

ACCURACY: 91.54% true positive, 97.02% true negative 

Officials have said they were working with at least nine manufacturers to try and get the project off the ground.

It is not clear what the threshold is for UK approval – one Chinese manufacturer believed to have been turned down by the Government claims its test is up to 98.6 per cent accurate.

PHE’s Professor Newton, however, said Government scientists were now having to go back to manufacturers and work with them to make the tests better.

Although tests appear accurate when used on people who were seriously ill with the coronavirus, they struggle to detect antibodies in people whose illnesses were mild.

Professor Newton said: ‘The test developed in China was validated against patients who were severely ill with a very large viral load, generating a large amount of antibodies,’ The Times reports.

‘We want to use the test in the context of a wider range of levels of infection including people who are quite mildly infected,’ he added. ‘So for our purposes, we need a test that performs better than some of these other tests.’ 

Professor Newton’s comments follow claims by an expert at Columbia University in  New York, who said low levels of antibodies make long-term testing difficult. 

Dr David Ho said that people who don’t get seriously ill appear to take much longer to develop antibodies and therefore might test negative in early stages of recovery.

He told The Guardian: ‘The problem is after a couple of weeks, the detection rate remains at about 50 per cent to 60 per cent, especially in asymptomatic or mildly symptomatic cases. 

‘But this may not be a fault of the tests, because even using more sensitive methods in the lab we can see the antibody levels are quite low.’ 

More detailed long-term follow-up of patients will be necessary to see whether antibody levels in the blood increase over time, he added. 

The US, which is now grappling with the worst coronavirus outbreak in the world – it has had more than 337,000 confirmed patients and 9,643 deaths – has already approved antibody tests and begun trialling them in Minnesota.

The Food & Drug Administration has given emergency use approval for a test developed by North Carolina-based Cellex Inc.

According to FDA paperwork the test is 93.8 per cent accurate at detecting positive cases of the virus.

And another internally-developed test is expected to start being used this week in the Mayo Clinic in Rochester, Minnesota, without FDA approval.

Government rules have been relaxed in the US so that companies can sell their antibody tests without getting approval from the FDA first. 

Antibody tests work by a drop of the patient's blood being placed into the sampler and then, as it flows through the device, the test catches any antibodies passing through and shows a line to indicate the types of antibodies that are present (Pictured: A scientist in a lab in Germany holds and antibody test)

Antibody tests work by a drop of the patient’s blood being placed into the sampler and then, as it flows through the device, the test catches any antibodies passing through and shows a line to indicate the types of antibodies that are present (Pictured: A scientist in a lab in Germany holds and antibody test)

This move, made by President Donald Trump’s administration in March, was intended to speed up the process of getting tests to patients. 

AMBULANCE DRIVER ‘DENIED TEST AND PRESSURED TO KEEP WORKING’

An ambulance driver in London who developed a sore throat and lost his senses of smell and taste says he feels pressured to continue working.

None of the symptoms are listed as officials reasons to self-isolate by the NHS or Government, but are widely believed to be caused by COVID-19.

The ambulance driver, who works around Croydon, south London, said he had been denied a coronavirus test to check he was still safe to work.

He reported his manager said ‘tests are expensive’ and ‘everyone is going to get it anyway’. The driver is employed by contractor HATS Group, which runs non-emergency healthcare transport.

Public Health England guidance says there is no requirement for ambulance drivers to wear protective equipment if they do not come face-to-face with patients.  

Helen O’Connor, an organiser at the GMB union, of which the driver is a member, said: ‘It is of great concern to GMB that this worker has not been immediately tested given he has COVID-19-type symptoms.

‘This means he will struggle to get permission to self-isolate and protect others from harm.

‘Once again serious questions must be asked about the failure of outsourced companies like HATs in their duty of care to workers, patients and the public.’ 

MailOnline has contacted HATS Group for comment. 

But experts say it is dangerous because bad tests giving false results could lead to people ignoring social distancing rules if they think they are immune to COVID-19.

Scott Becker, CEO of the Association of Public Health Laboratories, said that none of the local public health labs in his organisation will use any of the tests on the market.

He said: ‘The public needs to understand that all tests are not created equal,’ CNN reported.

‘These tests could create dangerous scenarios by giving people a false sense of security.’

Speaking about the tests being sold without FDA approval, Mr Becker added: ‘They’re selling these tests, but nobody has checked their quality. We need some level of scientific review and rigor on these tests.’

At least one company in the UK claims to have approval from ‘regulators’ for its tests to be used by healthcare professionals.

On Hive, an online pharmacy, a kit appearing to be made by Biopanda Reagents is advertised with the note: ‘UPDATE @02APRIL2020: UK REGULATORS HAVE APPROVED THIS TEST FOR HEALTHCARE PROFESSIONALS USE ONLY. STILL AWAITING APPROVAL FOR HOME SELF-TESTING.’

Many online test manufacturers in Britain also claim to be out of stock of coronavirus tests on their websites.

But the Medicines and Healthcare products Regulatory Agency (MHRA), which is in charge of permissions for devices to be used by the NHS, told the Financial Times it did not know of any antibody tests that had been approved for public use. 

Hive Pharmacy claims to be out of stock of an antibody test that has been 'approved by regulators for healthcare professionals use'

Hive Pharmacy claims to be out of stock of an antibody test that has been ‘approved by regulators for healthcare professionals use’

  • A previous version of this article suggested that test kits from the Chinese company Wondfo had been found not to be accurate enough for official use. The article has since been amended, and we have been asked to point out that Wondfo’s tests were not part of the review by Sir John Bell, which we are happy to clarify.  

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