Boris Johnson raised fears that tough Covid restrictions could continue well into the spring and beyond on Thursday as ministers refused to be drawn on plans for any potential easing of lockdown. While the vast majority of Tory MPs have toed the line since the new variant of the virus sent cases soaring, Downing Street’s reticence is already causing anxiety among a few backbenchers, who are urging an easing of the restrictions if vaccination rates stay on target. Downing Street is committed to reviewing the current England-wide lockdown in mid-February, by which point all people in the four top target groups for vaccinations should have been offered at least their first injection. But with 1,290 more UK coronavirus deaths recorded on Thursday, fears that infection rates in England might not even be falling, and the continued spread of the new, more infectious variant of Covid-19, Johnson was notably more cautious about lifting lockdown than he previously has been. “I think it’s too early to say when we’ll be able to lift some of the restrictions,” he told reporters during a visit to flood-hit Didsbury in Greater Manchester, when asked about the mid-February target. After Johnson’s spokesperson declined to rule out lockdown remaining in place until the summer, Priti Patel, the home secretary, was similarly cautious at the No 10 Covid press conference on Thursday afternoon. “It’s far too early to even contemplate where we go with restrictions,” she said, when asked about timings. Patel instead announced beefed-up fines to better enforce social distancing rules, with guests found at house parties of more than 15 people liable to incur fines of at least £800. Speaking earlier the education secretary, Gavin Williamson, said only that he “would certainly hope” schools reopen before Easter. The current plan is for pupils to return after the February half-term. While previously Johnson has appeared keen to talk up early exits from restrictions, No 10 officials have become much more cautious in recent days because of continued high levels of new infections, hospitalisations and deaths. “We’re less hopeful about moving quickly on unlocking than perhaps we have been: it’s because of the state of the pandemic,” said one Whitehall source. “The view is that we have to proceed cautiously and carefully.” As well as seeking evidence that the fall in new cases will not be reversed, they are waiting for the result of studies on whether the vaccines prevent transmission of Covid. The apparently slipping timetable brought a robust response from the Covid Recovery Group (CRG), which represents about 70 MPs concerned about the impact of lockdown. Mark Harper, the former chief whip who chairs the CRG, said if the mid-February vaccination target was met for the top four groups – older care home residents, those aged over 80 and frontline NHS staff, over-75s and over-70s – and they developed protection within three weeks, the prime minister “must start easing the restrictions” by 8 March. “Ministers must come forward now with a plan for lifting restrictions,” Harper added. Other MPs said they anticipated growing calls for the government to set out its expected road out of the restrictions now that the vaccine plan seemed to be going smoothly. “There’s big resistance to lockdown simmering with an insistence on showing the route map out of it all,” one former cabinet minister said. However, with the death figures so high, there is also a dilemma. One former minister said some among the CRG’s ranks were nervous about calling for the lifting of restrictions prematurely. “I think the general feeling is now that the virus is still not abating so we need to be cautious,” the MP said. “The group is being more circumspect. Certainly we need to be regularly informed by the government. But the new variant is clearly far more infectious.” There is also pressure from scientists to maintain robust restrictions because research suggests vaccination alone may not be enough to shrink the coronavirus epidemic. Prof Mark Woolhouse, chair of infectious disease epidemiology at the University of Edinburgh, said even in a best-case scenario it was unlikely vaccine uptake would be above 90%, meaning about 1 million vulnerable people would remain susceptible to Covid after the first phase of the programme. In addition, none of the approved Covid vaccines have a greater than 95% efficacy against Covid symptoms. “The general consensus is that a gradual releasing of restrictions would be possible but we would have to feel our way there, the way we did after the first lockdown,” Woolhouse said. But he added: “If [Covid vaccines] can’t take us past the [herd immunity] threshold, then we are going to be living with some kind of countermeasures for ever.”