Scientists and senior MPs have renewed calls for sweeping border curbs to protect the UK’s vaccination programme against new variants as Boris Johnson prepared to introduce tougher measures and Britain saw internal infections fall. The government is to announce new restrictions on arrivals into the UK this week, including mass testing of all arrivals. All passengers arriving in the UK will be tested for coronavirus on day two and day eight of their isolation – regardless of the country they have come from and whether they are at home or in hotel quarantine. The UK already requires all arrivals to have a negative Covid test from within the past 72 hours, taken while still abroad. With concerns over the risk to the UK’s vaccine programme from new coronavirus variants, Britons have also been urged to exercise caution booking summer holidays jointly with other households even within the UK this summer. Ministers said a third booster jab is likely to be needed in autumn to protect against new variants. A study found that the Oxford/AstraZeneca vaccine offered as little as 10% protection against mild to moderate infection, prompting Labour leader Keir Starmer to warn that the spread of the South African variant was the single biggest threat facing the UK. On Monday the government moved to calm fears about the vaccine, which scientists said would still protect against serious infection from the South African variant. The vaccine rollout has now surpassed government expectations for take-up, with more than 90% of over-75s in the UK having their first dose. The deputy chief medical officer, Jonathan Van-Tam, said the spread of the variant was minimal, with only 157 cases detected so far, and that the vaccine offered substantial protection against the most widespread variant in the UK and against serious illness. The South African variant did not seem to have a distinct transmission advantage over the variant now dominant in the UK, first seen in Kent, he added. At a Downing Street press conference on Monday, he was cautious in terms of how quickly lockdown and travel measures could be relaxed. “The more elaborate your plans are for summer holidays, in terms of crossing borders, in terms of household mixing, given where we are now, I think you have to say, the more you’re stepping into making guesses about the unknown at this point,” Van-Tam said. Other scientists went further, saying blanket hotel quarantine should be imposed for all UK arrivals to prevent variants spreading, instead of an approach targeting only 11 of the 41 countries where the South Africa variant has been detected, starting next week. “Variants can pop up anywhere and will continue to do so until the world gets a decent amount of vaccine, said Gabriel Scally, visiting professor of public health at Bristol University. “The proposed system is so leaky.” Scally favours a blanket quarantine of 14 days for all UK arrivals on the basis that it is effective against all variants of the virus, wherever they originate. “You can’t play catch-up with the virus,” he said. “You’ve got to get ahead of it and keep variants out no matter where they might come from.” Michael Head, a senior research fellow at Southampton University, said countries such as China and Australia had demonstrated how quarantine can keep cases down. “It’s difficult to rapidly discern the levels of risks in arrivals from different countries, so a blanket hotel quarantine policy across all countries is a better idea,” he said. Speaking on Monday, Johnson suggested border controls could be increased – though hinted that this would be when the UK greatly reduced its own infection rate. “They are most effective, border controls, when you’ve got the rate of infection down in your country,” he said. “For border controls really to make that final difference, so you can isolate new variants as they come in, you need to have infections really much lower so you can track them as they spread.” In addition to the new testing regime, the number of countries on the quarantine border list is expected to expand, government sources said, adding that the spread of the new variant would be a key factor in data assessed as the government drafts its blueprint for easing restrictions, to be set out from 22 February. Conservative MP Neil O’Brien, who co-chairs the party’s policy board, said he backed a toughening of the measures as new threats emerge, though he stopped short of calling for blanket measures. “Covid is likely to bounce around the world mutating for some time. Once in place, we can steadily toughen these border controls as appropriate,” he wrote on ConservativeHome. “The prize of us getting back to normal life in the UK seems worth the price of inconvenience for travellers; if you hate lockdowns, you should back the toughening of borders. “Sadly, managing the risk from new variants isn’t only about borders, because we’re seeing new variants originating in the UK … The less of the virus we have in circulation, the fewer new variants we will see, and the lower the risk of a really bad vaccine-dodging variation emerging inside the UK.” Yvette Cooper, the former shadow home secretary, said it was alarming that over half the countries with cases of the South Africa variant were not on the UK’s “red list” despite the potential threat it poses to the vaccine programme. She said there were “far too many holes” in the government’s border policy, which permits most new arrivals to travel on public transport to their homes to isolate and does not test on arrival. “If we want to protect our vaccine programme, we urgently need stronger measures at the borders to stop new variants from being imported.” However, Muge Cevik, a clinician in infectious diseases at the University of St Andrews and a member of the government’s New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), said there was too much emphasis on variants coming in from other countries and suggested the UK was right to concentrate on internal suppression. “The introduction of new variants from other countries, especially considering that international travel happens relatively at low level at the moment, is not our main challenge in the UK,” she said. At a briefing on Monday, the World Health Organization (WHO) and international bodies involved in the effort to get vaccines to lower-income countries stressed that there was every likelihood that the AstraZeneca vaccine would prevent severe disease, hospitalisation and death, even if it does not protect well against milder illness. The WHO will decide whether to give it emergency authorisation within days. Lab tests on the Pfizer/BioNTech vaccine found that it may still offer substantial protection against the variant. The WHO has recorded 41 countries with confirmed or probable cases of the B.1.351 variant first discovered in South Africa. Only 11 are on the government’s red list of countries travellers arriving from which must quarantine in hotels from next week. The government is facing questions over its preparedness for the introduction of the quarantine policy after it emerged that no formal contracts had been awarded to hotels to quarantine arrivals, even though the policy enters into force next week. The policy will apply to UK nationals and residents returning from 33 countries. All others must self-isolate at home – but previous research has suggested that many do not comply. Downing Street issued a commercial specification on Thursday evening, but no contracts have yet been agreed.