All travellers to England and Scotland from international destinations will have to test negative for coronavirus before they can enter the country, it has been announced. But will the tests actually make a difference? 

Under plans set out by Transport Secretary Grant Shapps, from next week passengers arriving in England by boat, train or plane – including UK nationals – will have to take a test up to 72 hours before leaving the country of departure.

Similar measures have been announced by the Scottish Government, while officials were said to be working closely with the devolved administrations in Wales and Northern Ireland on adopting them there.

Professor Lawrence S. Young, a virologist at the University of Warwick, says the introduction of this kind of testing has been “a long time coming”.

“Border control has been a major factor in restricting infection in other countries since the start of the pandemic,” he tells HuffPost UK. “These countries have not only used testing, but also mandatory quarantine in designated facilities.

“We should have done likewise last March.”

But while the new system is a step in the right direction, Prof Young points out it’s far from perfect. “There is a concern about the accuracy and reliability of the test that will be used, and whether repeat testing will be necessary rather than relying on a single test 72 hours before travelling,” he says.

“It is also very important that the current quarantine measures for returning passengers (self-isolation for 10 days) are enforced. It all feels a bit like ‘shutting the stable door after the horse has bolted’ but better late than never!”

Dr Alexander Edwards, associate professor in Biomedical Technology at the  University of Reading, also has some doubts. 

“At the moment, given very high levels of virus in the UK (higher than many other countries), it’s not going to affect overall UK infection levels to screen arrivals,” he says. “However, if there are variants elsewhere in the world which have substantial changes and are not present in the UK, then screening on entry becomes much more important.” 

Screening remains hard and Dr Edwards outlines three major pitfalls of the new system. “Swab tests are not perfect and can’t pick up every infected individual,” he says. “The accuracy of swab tests varies considerably. Even the best tests might miss one in five infected people.”

Secondly, he says testing asymptomatic people is especially difficult. “People can be infected but negative at the time of testing,” he says. “A typical incubation time of five days includes several days where no virus will be detected on a swab.”

Thirdly, he points out that people can get infected after the test – such as during travel.

Many of these limitations are difficult or impossible to avoid, so must be clearly communicated so people don’t assume they are ‘safe’ just because they had a negative test, he adds. 

Dr Joshua Moon, a research fellow in the Science Policy Research Unit (SPRU) at the University of Sussex Business School, thinks the new rules will make “some difference”, but we’ll have to wait to see how big a difference that is. 

“We know most of the transmission is within the UK rather than transmission across borders,” he adds. “This does raise a lot of doubt as to how effective it will be. I would liken it to protecting a burning building by removing any nearby matches. It will definitely help, but there’s still the burning building to take care of.“

Testing 72 hours before arrival will catch some of the cases, but not all of them, he adds. Increasing the frequency of tests would improve the system. 

“Another portion of cases could be caught by testing upon arrival and a further portion could then be caught with further testing 72 hours after arrival,” he says.
“But the main issue with a system like that is that it requires a large amount of testing capacity.”

HuffPost UK contacted the Department for Transport regarding the comments made by the scientists we spoke to. In response, Transport Secretary, Grant Shapps said: “We already have significant measures in place to prevent imported cases of Covid-19, but with new strains of the virus developing internationally we must take further precautions.

“Taken together with the existing mandatory self-isolation period for passengers returning from high-risk countries, pre-departure tests will provide a further line of defence – helping us control the virus as we roll out the vaccine at pace over the coming weeks.”