Boris Johnson has been urged to pull the plug on the final easing of coronavirus restrictions across England later this month, as he prepares to consider the latest data this weekend. With just 10 days until the final stage of his roadmap, when all legal limits on social contact could be removed, the prime minister is under growing pressure to err on the side of caution given a surge in cases of the Delta variant, first discovered in India. Jim McManus, vice-president of the Association of Directors of Public Health, said a complete lifting of measures risked cases and hospitalisations rising further, potentially leading to more variants that could undermine the vaccine rollout. He suggested that social distancing and wearing face masks should stay in place for the foreseeable future. “Relaxing our vigilance now, even after we have had the vaccine, could undo what we have all made huge sacrifices to achieve,” McManus said, adding that “patience now will pay off in the long run”. He said the freedoms that came into force on 17 May allowing people to socialise indoors in groups of six or from two households should be maintained, but a full reopening delayed. Johnson has repeatedly said he sees nothing in the data to suggest the final stage of unlocking on 21 June needs to be delayed, though the Guardian revealed this week that the chancellor, Rishi Sunak, was willing to accept a short delay if necessary. The pressure from backbench Tory MPs grew as the former prime minister Theresa May laid into the government over restrictions on international travel. She accused ministers of sending mixed messages and overseeing a chaotic system, and said they should be upfront about the fact that Covid will never be completely eradicated from the UK. “We are falling behind the rest of Europe in our decisions to open up,” she said in the Commons. “It’s incomprehensible that one of the most heavily vaccinated countries in the world is one that is most reluctant to give its citizens the freedoms those vaccinations should support.” The former transport secretary Chris Grayling said decisions being made by the government would cost hundreds of thousands of jobs, force businesses to close and leave the aviation industry “decimated for the future”. The former health minister Stephen Hammond accused the government of ignoring the data and making “illogical” choices about the green, amber and red lists that determine whether and where people arriving from other countries must quarantine. Whitehall officials are collecting the final pieces of data and finalising proposals for the different courses Johnson could decide to take, with the prime minister expected to hold meetings with ministers over the weekend and on Monday morning. A government source said the G7 summit in Cornwall, where Johnson and other world leaders are gathering this weekend, would “naturally make things more difficult” and “pile more pressure” on to the Monday morning.