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'Flawed' data led Government to rule out airport Covid tests

covid pcr test - Getty
covid pcr test - Getty

The Government has so far been opposed to scrapping quarantine in favour of Covid-19 testing at UK airports, claiming that trials runs show that only seven per cent of coronavirus cases would be detected on arrival.

But this figure is now being challenged by a group of health experts and data analysts who argue that a significant oversight is causing officials to wildly underestimate the effectiveness of airport testing.

In assessing research compiled by Public Health England, which underpins the Government’s quarantine policy, health consultancy Edge Health and analytical firm Oxera have jointly concluded that the data is based on an assumption that anyone with detectable Covid symptoms pre-departure will not board their flight.

The seven per cent figure thus only accounts for those passengers who develop symptoms during transit, and does not consider the possibility that travellers showing signs of infection will fly regardless.

Senior scientists and health experts at both companies, along with Dr Kit Yates co-director of the Centre for Mathematical Biology at the University of Bath, have subsequently published a new paper claiming that airport testing could actually identify up to 63 per cent of passengers.

Its authors have criticised other aspects of PHE’s research method, alleging that the latter’s figures are theoretical and not rooted in real-world data.

It therefore does not reflect the actual infection rates in other countries, and cannot accurately predict the threat of the infection spreading via inbound visitors.

George Batchelor, co-founder and director of Edge Health, said: “The way in which the PHE model is set up means that only a tiny proportion of infected passengers – those who become symptomatic or are asymptomatic but detectable by a PCR test during the flight – can be detected at arrival. This means the widely quoted seven per cent excludes anyone who is in theory detectable or symptomatic before the flight takes off.

“This evidently isn’t the case, and it leads to an underestimation of the effectiveness of testing on arrival (the seven per cent figure), raising serious questions about its role in informing government policy on passenger testing.”

Edge Health and Oxera have now submitted their findings to the Government’s Global Travel Taskforce, which is exploring ways in which testing can be used to reduce the quarantine period for inbound travellers.

The GTT is currently rejecting calls for PCR tests at airports, and is instead favouring a single-test approach that could potentially halve the quarantine period for visitors from 14 days to seven.

The Department of Health has defended this approach, iterating that any change to the testing for arrivals would need to "minimise the chance that positive cases are missed, and maximise compliance with self-isolation rules."

A government spokesperson said: “The scientific evidence on testing international arrivals was reviewed and approved by SAGE. Scientific modelling groups and the London School of Hygiene & Tropical Medicine independently generated similar results.

“International arrivals from non-exempt countries must quarantine for the full 14 days as the incubation period for the virus means passengers who do not follow this advice may pose a risk to others.

“Work is ongoing with clinicians, the devolved administrations and the travel industry to consider if and how testing could be used to reduce the self-isolation period.”