False positive Covid tests should still be treated as positive, expert warns

25 April 2021, 12:12 | Updated: 25 April 2021, 12:18

By Kate Buck

People who get a false positive Covid-19 result with a lateral flow test should still act as though its real until they get a better test, a Test and Trace chief has said.

Dr Susan Hopkins, Covid-19 Strategic Response Director to Public Health England and Chief Medical Adviser of NHS Test and Trace, said around 30% of people who have a lateral flow positive will then go on to test negative.

Currently, anyone who takes a lateral flow test which is positive is invited to have a PCR test at a centre or have one delivered to their home.

Read more: Eight police officers injured as they disperse crowds amid lockdown protest

If the PCR test - which is widely regarded as being more accurate - is negative, they are then released from restrictions.

Dr Hopkins told LBC's Swarbrick on Sunday: "Obviously when the infection rates are very low, the proportion of false positives to true positives changes. However we are still seeing a large number of these convert to PCR positives tests as well.

Susan Hopkins spoke with LBC's Tom Swarbrick on Swarbrick on Sunday
Susan Hopkins spoke with LBC's Tom Swarbrick on Swarbrick on Sunday. Picture: PA/LBC

“Everyone who does a paternal flow test is invited to do a PCR test if it’s positive. And that will allow them to know the true status and be released from restrictions they’re under because of the lateral flow test positivity.

“If the lateral flow test is positive people need to act as if it’s positive.

"That’s what will reduce transmission. We’re still seeing 70% of those people who take a lateral flow and then take a PCR test convert to be positive. That's a high number.

“If we can reduce the transmission of infection in that period where your lateral flow test is positive that will prevent us from having to have further restrictions.”

But Dr Hopkins added the number of false positives may actually be lower than originally thought.

"We can’t say it’s truly a false positive. It may have been positive at the time and then the PCR taken at a later time was then negative," she told Tom.

“Nonetheless we take the PCR as the best test and so we release people if their PCR test was negative.”

More Tom Swarbrick

See more More Tom Swarbrick

Raab: Party can't act on Islamophobia claim 'in absence of formal complaint'

Raab: Party can't act on Islamophobia claim 'in absence of formal complaint'

Exclusive
Former Brexit Minister David Davis told LBC the Tories are "paralysed" as long as Johnson remains in power.

'Kindest thing' for Boris Johnson’s legacy would be for him to go, David Davis tells LBC

Swarbrick on Sunday | Watch live from 10am

Swarbrick on Sunday 23/01 | Watch again

Labour Party is 'full of people that don't like this country', claims Tory MP

Labour Party is 'full of people that don't like this country', claims Tory MP

Caller says he knows Boris Johnson is a 'liar' and will support him 'no matter what'

Caller says he knows Boris Johnson is a 'liar' and will support him 'no matter what'

Tom Swarbrick grills Tory MP on 'technicality' allowing No.10's garden party

Tom Swarbrick grills Tory MP on 'technicality' allowing No.10 party

Streeting: 'No comparison' between No.10 partygate and Starmer beer photo

Streeting: 'No comparison' between No.10 partygate and Starmer beer photo

MPs Chris Bryant and Peter Bone had very different perceptions of the PM.

'He's making fools of every single Tory who comes on to defend him': MPs clash over PM

Swarbrick on Sunday | Watch live from 10am

Swarbrick on Sunday 16/01 | Watch again

Winston Churchill's grandson shares fury at Colston Four verdict

'They're on the wrong side of the law!' Churchill's grandson rages at Colston Four verdict

'Has Molly-Mae taken over the Conservative party, Mr Zahawi?'

'Has Molly-Mae taken over the Conservative party, Mr Zahawi?'

The Shadow Chancellor told LBC: "Broken promises won't pay people's bills"

'A catastrophe': Shadow Chancellor hits out at govt over spiralling energy costs

Nadhim Zahawi said he "didn't recognise" the report that free lateral flow tests will be scrapped in the coming weeks.

Lateral flow tests will remain free for now, minister insists

Swarbrick on Sunday | Watch live from 10am

Swarbrick On Sunday 09/01 | Watch in Full

Best of 2021: Tom Swarbrick hears from desperate publican

Best of 2021: Tom Swarbrick hears from desperate publican

Professor Alastair Grant believes the government didn't introduce new measures because cases appear to have 'plateaued'

Covid cases 'appear to have flattened', virus modeller tells LBC