Lateral flow Covid tests could ‘drive up infection rates’ as lockdown eases
LATERAL flow coronavirus tests could drive up infection rates as lockdown restrictions ease, experts have warned.
The government has rolled out free rapid Covid tests that produce results within 30 minutes in order to get the country back on its feet as more venues start to reopen.
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But the lateral flow tests are not as accurate as PCR tests, which are being given to people who have symptoms.
The lateral flow tests are on offer to everyone - even people who don't have symptoms - and a third of people who contract Covid are asymptomatic.
Public Health England's (PHE) Dr Angela Raffle and Dr Mike Gill have said the rapid tests could produce "false reassurances".
Writing in the , the team said the rapid tests are already "skewing nationwide data on test numbers, cases, and positivity rates, making trends harder to interpret".
They said: "False positive results will be a problem when prevalence is low, even with PCR confirmation.
"And the temptation for people with symptoms to opt for unsupervised, rapid, and lower sensitivity self-testing may lead to false reassurance, as happens with other screening, leading to potential increases in transmission."
One expert said the PHE officials had "missed the point" of testing.
Prof Mark Woolhouse, Professor of Infectious Disease Epidemiology at the University of Edinburgh, said the control of infectious diseases depends on finding cases and finding them early before the infection can be passed on.
He said: “People infected with novel coronavirus are infectious for 24-48 hours before they show symptoms, and this period is thought to account for up to half of all transmission.
“This pre-symptomatic infectious period makes novel coronavirus much more difficult to control. Asymptomatic testing can reveal these crucial pre-symptomatic infections – there is no other way to do this."
PCR tests are known as the "gold standard" when it comes to testing for Covid.
These are the tests that will also be required for foreign holidays.
People who test positive with the rapid lateral flow tests are also advised to take a PCR test in order to sure up the results.
In developing a testing programme, the experts added that speed was favoured over accuracy.
They said: "The challenge was framed as 'find a valid test and roll it out as quickly as possible' rather than 'devise best systems for using testing to help contain the pandemic'.”
Each day around a million coronavirus tests are being carried out by Brits - but just over a quarter of these are the more reliable PCR tests.
The mass testing pilot was first rolled out in Liverpool under 'operation moonshot'.
Prime Minister Boris Johnson previously hailed mass testing as a way back to normal life, helping us get back to doing the things we love most.
It is thought that mass testing could be used at big sporting events and concerts.
'NO PROOF'
The experts added that there is "no empirical data" to support mass SARS-CoV-2 screening, and home self-testing has not been evaluated.
They said: "The December surge of infections in Liverpool, where trained testers screened a quarter of the population, was no lower than in other cities without screening.
"The effects of screening university students from December remain unclear, and data have not been made public.
"Care homes conducting asymptomatic testing have struggled to adhere to protocols and experienced no fewer outbreaks than care homes without asymptomatic testing."
They added that from early March, testing of millions of schoolchildren was accompanied by a short lived rise in the ascertainment of school age cases, but there is no evidence of change in the trajectory of case rates in older age groups, suggesting a lack of effect on onward transmission.
PHE states that the UK has now carried out more tests than anywhere in Europe.
Covid response director Dr Susan Hopkins said the tests have helped millions of kids return to school safely.
She highlighted that 149.2million Covid tests have been carried out and that since its launch, the NHS Test and Trace app has prevented 600,000 Covid cases.
However some experts have not agreed with the editorial in the BMJ and have sided with Dr Hopkins.
Dr Michael Joseph Mina, Assistant Professor of Epidemiology at Harvard T.H. Chan School of Public Health said: "Testing is our eyes on this virus. Without testing, we simply cannot see it. The more eyes the better – particularly when there is little downside.
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“If the testing is as easy as brushing your teeth, then it’s a great addition to a comprehensive plan to limit spread.
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"And it can be dynamic. The testing can be throttled up or down depending on the transmission of the virus within the population at the time.
"When cases are at a minimum, we can slow the testing down. But as long as people are already accustomed to it and have access, then if cases start to rise in a given community, then the testing can be throttled up enough to limit spread."