Covid lateral flow tests don’t work as well on children, according to a study which casts doubt on whether they can curb the spread of the virus in schools.
All secondary school students in Britain are currently encouraged to do LFD tests at least twice a week.
But writing in the BMJ’s Evidence-Based Medicine, experts said the rapid kits were not as effective as hoped in youngsters.
A team of British and German scientists pooled together results from 17 old studies, involving over 6,000 children, that analysed the efficacy of lateral flows in detecting Covid in young people.
The team found that overall, the tests — which give results in as little as 15 minutes — only detected 64 per cent of Covid positive children.
Detection rates increased to 72 per cent when children had symptoms of Covid, like a new continuous cough or a change in the sense of taste and smell.
However, the swabs spotted little over half of the infected children who didn’t have symptoms.
The authors said their findings mean LFDs would fail the minimum standards of the UK’s Medicines and Healthcare Products Regulatory Agency, the US’s Food and Drug Administration, and the World Health Organization.
Each of these bodies require Covid testing kits to have a minimum success rate of about 80 per cent.
It comes amid fears the return of children to school could trigger another uptick in Covid cases, just as the Omicron surge appears to be fizzling out.
A new study suggests that commonly used lateral flow tests fail to meet UK regulator standards when used on children. The analysis of available data found that even in children with Covid symptoms, the test kits only detected 72 per cent of cases, 8 percentage point slower than the UK regulator’s minimum accuracy standards
Regular lateral flow tests are a key part of Government efforts to control the spread of Covid in schools. Here Erin Horn takes a test Outwood Academy in Woodlands, Doncaster in Yorkshire (file image)
A new analysis suggests lateral flow test kits, like the one pictured, only detect about, 64 per cent of Covid cases in children, well below the UK’s regulator minimum standard of 80 per cent success
Covid cases in children have rocketed up in the few days back at school, with over 240,000 total confirmed or suspected Covid cases, with more children also in isolation. Regular lateral flow tests by students are a key part of Government plans to curb the spread of the virus in schools but a new study has cast the effectiveness of such tests on children into doubt
How to do a rapid lateral flow test
Rapid lateral flow tests are for people who do not have Covid symptoms, such as a high temperature, a cough or a loss or change to smell or taste.
The tests give a quick result using a device similar to a pregnancy test.
People with Covid symptoms should do a PCR test.
Before doing a rapid lateral flow test the NHS advises:
- try not to eat, drink, smoke or vape 30 minutes before doing the test as this may affect the result
- read the instructions carefully
- clean the surface you’re putting the test on
- check nothing in the test kit is damaged or broken
- start the test within 30 minutes of opening the test kit
If your test requires a throat swab:
- open your mouth wide and rub the swab over your tonsils (or where they would have been)
- avoid the end of the swab touching your teeth, tongue and gums
- put the same swab inside your nose (about 2.5 cm up or until you feel some resistance)
If your test requires a nose swab only:
- put the swab inside your nose (about 2.5 cm up)
Completing the test:
- put the end of the swab into the tube so it’s in the liquid
- squeeze the liquid from the tube onto the test strip
- check the waiting time in the instructions that came with your test kit
- wait for the time shown in your test kit instructions
- read your result
- report your result on the Government website
Researchers added that the findings only include samples taken by professionally trained individuals and not self testing at home, which would likely only be a detriment to the accuracy.
The authors added it is unknown if repeated, regular LFD testing would help to alleviate some of these detection problems.
One of the authors, Dr Naomi Fujita-Rohwerder, of the Institute for Quality and Efficiency in Health Care in Cologne, Germany, said the findings may cast doubt on using LFDs to detect Covid cases in children.
‘Taking into account test-specific pooled results, no test included in this review fully satisfied the minimum performance requirements as recommended by WHO…the US…or the MHRA in the UK,’ she said.
‘This may affect the planned purpose of the broad implementation of testing programmes.’
The authors only looked at studies that used eight different kits, meaning some of the 500-plus tests currently on sale across the world may be more accurate.
All 17 of the studies included in the new analysis were published between the start of 2020 and May 2021, meaning they will not have accounted for Omicron.
The researchers did offer any reasons why the tests did not perform accurately on detecting Covid in children.
Nor did they offer a comparative estimate of LFD accuracy in adults though other studies have estimated this at being 72 per cent of symptomatic cases, though the UK Government insists the tests catch over 80 per cent of the most infectious individuals.
Regular LFDs are one of the cornerstones of the UK Government’s attempt to curb the spread of the virus amongst children.
And the UK Health Security Agency (UKHSA) insists the kits remain the best way to detect Covid among the wider population.
Lateral flow tests have been under the spotlight in recent week as ministers urge Britons to take a test before meeting others in an attempt to reduce the chances of people unknowingly passing the virus on to others.
But scores of Britons complained over the Christmas period that they received a negative lateral flow result only later to test PCR positive, prompting concerns about the kits’ accuracy in detecting the Covid variant Omicron.
The scrutiny also comes with a change of guidance, with people now only needing a positive LFD test to being self-isolation, no longer needing a follow-up with a more accurate PCR test.
Covid rates in schools jumped in England in the first week back from the Christmas holidays, according to official data.
A total of 315,000 children were absent from state schools on January 6 because of Covid-related reasons. This represents about 3.9 per cent of students, according to the Department of Education.
It was a marked increase from the previous report’s 236,000 Covid-related absences recorded on December 9.