A director of public health is advising people to isolate if they have Covid-19 symptoms even if they subsequently receive a negative PCR test result.
GPs in the West reported seeing “a stream of patients” who had positive lateral flow tests but then received negative PCR results.
The UK Health Security Agency stated that it was looking into the cause.
However, according to one Independent SAGE adviser, self-isolation following a negative test may be impractical for some.
While it is well understood that lateral flow device (LFD) tests can occasionally produce a false negative, false positives are much more uncommon.
The UK Health Security Agency stated that it was made aware of “some areas across the country” anecdotally reporting positive LFD results followed by negative PCR tests.
It also stated that there was no evidence of any technical issues with LFD or PCR test kits in relation to those reports at this time.
It stated that no test was 100 percent accurate, but the likelihood of a false positive result remained low.
A growing number of people have taken to social media to report on the occurrence.
Many have come from Bath, Bristol, and Swindon, but it is believed that it is also happening elsewhere in England.
Bath and North East Somerset Council’s director of public health, Becky Reynolds, said the council was aware of the situation and added, “It is confusing [for people].” “I believe we should just bear with it until the investigation is completed.”
Ms Reynolds stated that they were told that “PCR are the gold standard” and that a negative PCR means they do not have Covid.
“The advice is also to think about your local situation, do an individual risk assessment… so what is the likelihood that even if the PCR is negative, you may still have Covid?” she said.
“If you think about it, there’s a good chance you have Covid, even if the PCR comes back negative, so treat it as Covid and self-isolate.”
“Myself and my colleagues have seen a stream of patients with what we would consider very typical Covid symptoms,” said Dr Lucy Pocock, a GP from Cadbury Heath Healthcare in south Gloucestershire.
“Several of these patients have had multiple lateral flow tests, all of which have come back positive, and have then gone on to have a PCR test, which has come back negative.”
“What’s concerning here is that all of these people are clearly symptomatic and have a very unexpected negative PCR result.”
Unwittingly spreading Covid
Caroline, a Bath teaching assistant, and her 12-year-old son Harry both tested positive on lateral flow tests three times this week and received two negative PCR test results.
“I’ve never had a line on the lateral flow test before,” she explained, “and I’ve been testing twice a week, every week, because I work in a school.”
But I got a line this week and started having symptoms.
“I also spoke with my doctor, who said it was Covid, especially with the symptoms, and that I should self-isolate, which I have been doing.
“I believe people should be aware of this because otherwise they may be going out into the community and spreading it without realising it because of a negative outcome.”
Hayley Hodge, from Stroud, became ill two and a half weeks ago with a fever and a cough.
“I took a lateral flow, as did my 14-year-old son, and they both came back positive, but our PCRs came back negative,” she explained.
“My mother then became ill and tested positive on a lateral flow test but negative on PCR.
“I thought I was going insane because my research kept telling me that, while PCRs are the gold standard, lateral flow test false positives are extremely rare.
“We used a variety of test kits as a family. Some were brand new, while others had been in the house for a few months or longer. So, based on our experience, I don’t believe it’s due to faulty testing kits.
“I know people are now on the case so hopefully they will find answers soon.”
‘Can’t access support’
Kit Yates, a member of the Independent Scientific Advisory Group for Emergencies [SAGE], has called for the situation to be investigated “seriously and quickly.”
“Public health England have suggested informally that you should still self isolate even if you get a negative PCR test, especially if you have symptoms,” the University of Bath professor continued, “although that isn’t government guidance.”
The problem is that if you don’t have a positive PCR test, you won’t be able to get the isolation help you need.
“So, even if they get a negative PCR test, telling people to self-isolate may not be practical for many people.”
Susan Hopkins, the UK Health Security Agency’s chief medical advisor, stated, “We have been made aware of some areas reporting positive Lateral Flow Test test results with subsequent negative PCR tests, and we are investigating the cause.”
She stressed the importance of carefully reading and following the instructions for use on the test kit in order to avoid incorrect readings.