Doctors condemn secrecy over false negative Covid-19 tests

Doctors’ leaders have condemned ministers and Public Health England (PHE) for throwing a “shroud of secrecy” over how many coronavirus tests on NHS staff and patients produce wrong results.

The Hospital Consultants and Specialists Association (HCSA) has demanded an end to “evasion” and the “wall of silence” around how many swab tests result in false negative readings.

The tests, in which samples are taken from someone’s throat and nose, are vital in controlling the spread of Covid-19 in hospitals because they are used to check whether NHS personnel and inpatients have the virus and might unwittingly pass it on.

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Swab tests are known to be unreliable. Doctors and hospital bosses have told the Guardian that about 25% of those carried out during the pandemic wrongly said that a carrier was not infected. Medical research has found that as many as 29% yield a false negative.

The HCSA, which represents thousands of frontline medics, is worried that staff wrongly declared to be virus-free after being tested could lead to patients becoming infected while in hospital.

Boris Johnson recently told MPs that hospital-acquired Covid-19 was leading to an “epidemic” of patient deaths. A PHE study last week found that as many as 20% of inpatients and 90% of healthcare workers contracted the virus while in hospital.

In a strongly worded letter to PHE, the HCSA’s general secretary, Dr Paul Donaldson, a consultant microbiologist, said: “Statements by PHE offcials and others place the incidence of false negatives somewhere between 20% and 30%. 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.”

Related: Up to 20% of hospital patients with Covid-19 caught it at hospital

Doctors feel “deep concern and frustration” at PHE’s “systematic lack of information” about the different types of coronavirus tests and say a “wall of silence seems to have been erected around the issue”.

The HCSA is also angry that the Department of Health and Social Care (DHSC) has refused to fully answer parliamentary questions which Labour has tabled to find out more about the tests.

Justin Madders, a shadow health minister, asked the DHSC what recent estimate it had made of the false-negative rate of each of the Covid-19 tests in use. In reply Nadine Dorries, the health minister, said only that “viral detection tests have high levels of clinical sensitivity at close to 100%”. The staff of NHS laboratories do everything they can to minimise false positives, she said.

Asked by Madders to name all the Covid-19 tests in use, Dorries declined to do so. She simply replied: “There are eight key testing platforms which deliver the majority of testing. All these tests are clinically validated and have high levels of performance.”

Nor would Dorries tell Madders which tests for Covid-19 the NHS had stopped using and why. Instead she reiterated that eight clinically validated tests were being used.

Recent research published in the British Medical Journal found that between 2% and 29% of Covid-19 tests produced false negatives. The number of “true positive” results from nasal swabs was as low as 63% and from throat swabs just 32%, the lead author, Dr Jessica Watson, reported.

Prof Andrew Goddard, president of the Royal College of Physicians, said: “The main issue from the perspective of physicians has been, until recently, the lack of access to testing as shown by our survey. Even though the test is far from perfect the inability for healthcare and social care workers to access the test for themselves, their patients and their families has hampered our ability to respond to the pandemic and control its spread within hospitals and care homes.”

Dr Nick Phin, PHE’s incident director, declined to respond directly to the HCSA’s concerns. He 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.”