People arriving in Britain should be tested to cut quarantine time, scientists have urged, as speculation mounts that more holiday destinations will be axed from the air bridges list. A growing number of countries are being added to the UK’s quarantine lists, with many Britons holidaying in France forced to make a frantic dash back before 4am on Saturday morning to avoid a 14-day period of isolation. Croatia, Turkey and Greece are also reporting rises in Covid cases, leading to speculation that they, too, could soon be added to the quarantine list. But a number of studies have shown that testing can reduce quarantine time. Public Health England documents released by the government’s scientific advisory group for emergencies (Sage) last week showed that, with various assumptions such as tests working perfectly, testing travellers on arrival in the UK and five days into a seven-day quarantine prevents 85% of travellers who are asymptomatically infected or incubating illness from mixing freely and potentially introducing infections into the UK. “There are several reasons for this; the isolation period of itself will ensure that a proportion of infected people pass through their illness and cease being infectious, and the testing regime adds safeguards for detection of asymptomatic and prolonged infections,” a PHE spokesperson said. Meanwhile, a study by researchers at the London School of Hygiene and Tropical Medicine found that testing arrivals seven days into an eight-day quarantine period could cut the number of infectious people re-entering the community by 94%, compared with no testing or quarantine. “It is relatively safe to reduce quarantine periods if they are combined with a test before release” Prof John Edmunds of the LSHTM told the Guardian. “However, the period of quarantine still needs to be of the order of seven days or more and the test should be done at the end of this period. Testing at the airport is fairly ineffectual.” Dr Michael Head, a senior research fellow in global health at the University of Southampton, said it was time policymakers considered such testing regimes. “We can’t really avoid quarantining people who are coming back from high-risk areas – I think some period of quarantine is necessary and essential,” he said. But, said Head, the testing of arrivals should be considered to reduce the length of quarantine to help people get back to work and daily life sooner. “Certainly a test at seven days or thereabouts would probably be fine and might well increase compliance from the public as well, in terms of their quarantining when they come back,” he said. Ian Jones, a professor of virology at Reading University, said he backed testing on arrival and during the first week of quarantine, suggesting travellers should be tested on alternate days and allowed back into the community after the third negative test. “The issue is that many holidaymakers may not have been in areas of the destination country where virus was circulating so are very unlikely to have encountered it,” he said. “For them the whole [two weeks of quarantine] is just a waste of time and anything that can speed this up, and indeed uses a more scientific approach to scoring positive or negative [for Covid] than waiting for symptoms to develop, would seem to be a good idea.” But David Heymann, a professor of infectious disease epidemiology at LSHTM, said there was limited evidence as to whether such testing regimes should be brought in, noting testing on arrival would only detect people infected during the week before they travelled, while testing was best done if a person in self-isolation developed symptoms. “If a seven-day testing regime were to be tried there would need to be monitoring to determine its effectiveness and there would always be a question whether infection occurred some time during or just preceding self isolation and was not therefore related to travel,” he said. Prof Rowland Kao of the University of Edinburgh also said the situation complex, noting using testing to reduce quarantine may be an option if infections from outside the UK are reducing, but the approach is more problematic when they are rising. “Reducing quarantine and replacing with testing represents an added risk, not a reduction of risk – and that’s precisely what you want to avoid if the inherent risk is getting worse,” he said.