Coronavirus testing chief probed over false negative readings in one of every five results
As many as one in five coronavirus swab tests could give false negative readings, MPs have heard.
Baroness Dido Harding, head of the NHS Test and Trace programme, was challenged over the risks of false negative tests when she appeared before the Health and Social Care Select Committee.
Former health secretary and committee chairman Jeremy Hunt asked about evidence from the University of Bristol and Johns Hopkins University in the US which suggests 20% of negative results could be false.
Mr Hunt said: “Now the guidance, as I understand it at the moment, is that if you call in with symptoms and your test comes back negative, the guidance says that you and other household members no longer need to self-isolate.
“But we know from Bristol University and Johns Hopkins University that up to 20% of test results are false negatives – so that people actually have Covid-19 but the test says they don’t.
“Why does the guidance then ask those people to have another test?”
Baroness Harding (pictured) said that the question is one for medical and scientific experts but added: “I think we all do recognise that there is error in the testing system but current guidance is exactly as you set out, and that’s what we’re building the service to deliver.”
Mr Hunt questioned why people are not offered a second test if they have tested negative “because we wouldn’t want people going back into the community if they could be spreading it”.
Baroness Harding added: “My understanding of the guidance is that if, after having a negative test, you and your household are free to go back into normal life but if you do continue to feel unwell after a couple of days we would advise you to stay at home and take another test in a few days’ time.
“We are not short on testing capacity and actually I want people who are not feeling well to feel really confident that they can book a test.”
Baroness Harding added: “As I understand it there are a number of different studies, and there’s quite a wide range in those studies suggesting the range can be between two and 20-odd per cent.
“So I don’t think that there is precision in the scientific evidence that we would all like there to be.”
A Department of Health and Social Care spokeswoman said: “Testing is reliable and effective, with tens of thousands of people getting fast, accurate results every day.
“We have been working closely with a range of partners to ensure information about testing is transparent, and that results are returned quickly and accurately to help us track the virus and save lives.”
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