Lab checks return matching result for 82% of positive rapid Covid tests

Ian Jones and Tom Pilgrim, PA

Labs returned a matching outcome for more than 80% of positive rapid coronavirus tests sent for a check, data suggests.

Figures from Public Health England’s Covid-19 dashboard show 26,145,310 lateral flow device (LFD) tests were carried out in England between March 8 and April 4, providing 30,769 people with a positive result.

Of the positive results, 16,930 were sent to a lab for a confirmatory check using the PCR (polymerase chain reaction) technique.

These checks found 3,034 (18%) of the LFD results were negative, while 13,896 (82%) were positive.

The data analysis does not reveal how many people received a negative LFD result when they were positive.

HEALTH Coronavirus
(PA Graphics)

Lateral flow tests do not need laboratory assessment and can give results in fewer than 30 minutes.

They form an integral part of the Government’s efforts to test NHS and care home staff as well as at businesses, schools, asymptomatic testing sites and at-home testing for the families of school pupils.

Scientists have previously said the mass use of rapid turnaround tests may have the “opposite effect” of what they are aiming to achieve because of high rates of false results.

They said false results could mean more workplaces and schools are forced to close, with people required to self-isolate when a positive result is returned.

But the Government has defended the accuracy of the tests, with the Department of Health and Social Care (DHSC) saying last month that analysis showed LFDs have a specificity of at least 99.9% when used to test in the community.

The latest figures from the Government’s Test and Trace programme show that four million LFD tests were conducted in England in the week to April 7 – down from 5.5 million the previous week.

The DHSC said the drop coincided with the end of the spring term for schools.

HEALTH Coronavirus
(PA Graphics)

By contrast, 820,000 PCR tests were conducted in the week to April 7.

This was the 11th successive week in which more LFD tests were conducted than PCR tests.

A total of 19,196 people tested positive for Covid-19 in England at least once in the week to April 7. This is down 34% on the previous week and is the lowest number since the week to September 2.

A total of 88.8% of people who were tested for Covid-19 in the week ending April 7 at a regional site, local site or mobile testing unit – a so-called “in-person” test – received their result within 24 hours.

This is down slightly from 90.6% the previous week.

Prime Minister Boris Johnson told the House of Commons on June 3 last year that he would get “all tests turned around within 24 hours by the end of June, except for difficulties with postal tests or insuperable problems like that”.

Of the 16,926 people transferred to the Test and Trace system in the week to April 7, 87.9% were reached and asked to provide details of recent close contacts – a slight drop from 90.5% the previous week.

Some 11.4% of people were not reached while 0.8% did not provide any communication details.