THREE in ten negative coronavirus tests for NHS staff could be wrong, a doctors’ union is warning.
The Hospital Consultants and Specialists Association (HCSA) fears 20 to 30 per cent of tests are giving hospital workers negative results even though they’re still infectious – fuelling the spread of Covid-19 in hospitals.
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And the union is now urging the Government to change the rules so that doctors and nurses need two negative tests to return to work – to prevent hospitals becoming ‘hotspots’ of infection.
The HCSA also said that ministers should publish the false negative rates for all its antigen tests – which determine whether someone is currently carrying the virus and are actively infectious.
In a strongly-worded letter to Duncan Selbie Chief Executive Public Health England (PHE), seen by The Telegraph, Dr Paul Donaldson, General Secretary of the HCSA revealed his “deep concern and frustration” at the body’s “systematic lack of information” over the reliability of its polymerase chain reaction (PCR) tests.
‘Deep concern and frustration’
He said: “Statements by PHE officials and others place the incidence of false negatives somewhere between 20 and 30 per cent.
“If confirmed, this is a worryingly high rate which raises the prospect of many infected individuals, possibly without symptoms, being passed fit to return to healthcare settings where they will transmit Sars-CoV-2 to colleagues and patients.”
The NHS is currently using antigen tests in hospitals to find out if someone is currently infected with Covid-19.
Samples are taken using a swab – which resemble a large cotton bud – from deep inside the nose and throat before being sent off to a lab for testing.
Coronavirus testing: What is the difference between antigen and antibody tests?
Coronavirus tests are key to getting a clearer idea of the scale of the outbreak in the UK and getting a handle on it.
There’s been a lot of talk about the two different types of tests that the government are ramping up.
The government refers to them as the ‘have you got it’ antigen test or the ‘have you had it’ antibody test.
Here we explain the difference between the two…
What is an antigen test?
Antigens are found on the surface of invading pathogens, including coronavirus.
Testing for antigens can determine whether someone is currently carrying the virus and are actively infectious.
The NHS is currently using antigen tests in hospitals to determine if someone is currently infected with Covid-19.
Samples are taken using a swab – which resemble a large cotton bud – from deep inside the nose and throat before being sent off to a lab for testing.
Most labs use a method called the polymerase chain reaction (PCR), which takes several hours to get a result.
It can take days for labs to run the tests and tell people their result.
Several companies are working on ways to fast track this type of testing.
What is an antibody test?
When a person gets infected with antigen, the body starts making specially designed proteins called antibodies in response – as a way to fight the infection.
After they recover, those antibodies float in the blood for months, maybe even years.
That’s the body’s way of defending itself in case it becomes infected with the virus again.
So an antibody test specifically looks for antibodies which will be able to tell whether you’ve already been exposed to Covid-19.
Anyone who has already had the illness is presumed to be immune to getting it again – at least, in the intermediate term.
This would allow them to go back to work safe in the knowledge that they are unlikely to become infected again or pass the virus on.
The check that has been developed for Covid-19 is a finger-prick blood test, with the samples sent to laboratories and results available within a few days.
Dr Hilary Jones, a GP and resident doctor on Good Morning Britain, explained that it works “almost like a pregnancy test, except you need a drop of blood”.
These tests are being developed by several different firms and Public Health England (PHE) is also working on its own test.
They still need to be validated to ensure they give accurate results.
Most labs use a method called the polymerase chain reaction (PCR), which takes several hours to get a result.
It can take days for labs to run the tests and tell people their result.
When quizzed on the false negative rates of these tests in Parliament earlier this month, Nadine Dorries, the health minister for patient safety, claimed the Government was currently using eight different tests that are “clinically validated and have high levels of performance”.
Following the HCSA’s letter, Dr Nick Phin, Public Health England Incident Director said: “The UK’s national testing system is built on strong foundations using the latest scientific evidence and expert advice.
“The different tests in use have been assessed as performing to manufacturers’ specifications.”
Despite this, Dr Claudia Paoloni, HCSA’s president, said that NHS staff had suffered a string of problems with antigen tests.
It could create a hotspot area within the hospitals where we are causing a spread of the infection
Dr Claudia Paoloni
This included swabs being too long to fit into the containers they are sent to the lab in – meaning people had to snap them to fit them into the cases, which could void the test.
And Dr Paoloni added that the HCSA was worried about the fact medics are being sent back to work to treat vulnerable patients while unwittingly still infectious.
In particular, she pointed out that this was occurring at a time when the Government is encouraging vulnerable non-Covid-19 patients to return to hospitals for their treatments.
“It could create a hotspot area within the hospitals where we are causing a spread of the infection,” she told The Telegraph.
“Therefore this is a higher risk, if we don’t get this right, that a second wave could occur and with higher numbers and be more significant.
“Also, people will retract again as they will be too fearful to come in if they see that infections are going up because of what is happening in hospitals.”
Recent research published in the British Medical Journal found that between two per cent and 29 per cent of Covid-19 tests produced false negatives.
The lead author of the study, Dr Jessica Watson, reported that the number of “true positive” results from nasal swabs was as low as 63 per cent and from throat swabs just 32 per cent.
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