A “plan C” for tougher coronavirus restrictions has been discussed in official circles, a senior civil servant has confirmed, despite ministers denying that tougher measures are an option this Christmas should the rate of new cases continue to rise. The indication of planning for potentially harsher restrictions comes as senior scientists and Labour push for the rollout of “plan B”, an existing package of “light-touch” measures including advice to work from home and compulsory face masks in some settings. Last week the health minster Edward Argar denied that anything of the order of a plan C – which could include restrictions on household mixing at Christmas – was being contemplated by the government. However, the term was used on Tuesday by Prof Lucy Chappell, the chief scientific adviser for the Department for Health and Social Care (DHSC), when MPs asked whether a failure to bring in plan B actions now may mean tighter restrictions are needed later. “I think it suggests that plan A and plan B and whatever the plan C looks like are mutually exclusive, but they are not,” she told the science and technology select committee on Covid transmission. Chappell was then questioned on whether a plan C did, in fact, exist. “It has been proposed … The name has been mentioned. It has not been extensively worked up,” she said, adding that at the DHSC, “at the moment, the focus is on plan B”. Dr Thomas Waite, the interim deputy chief medical officer at the DHSC, said it was up to the government, not scientific advisers, to decide whether plan B should be introduced. He suggested there was no single measure or threshold that would inform the move, rather a consideration of various factors, including age-stratified case rates, the rate of change in hospital admissions, the impact of waning immunity, and the influence of booster jabs. The evidence session also included testimony from Prof Sir Andrew Pollard, the director of the Oxford Vaccine Group, who suggested that although transmission in the UK was high, focusing on daily figures of Covid hospitalisations and deaths was misleading, noting they included people who needed medical help or had died for another reason. Pollard also suggested that regular testing in schools was problematic. “Clearly, the large amount of testing in schools is very disruptive to the system, whether that is the individual child who is then isolating, because they’ve tested positive, but they’re completely well, or it’s because of the concerns that that raises more widely in the school,” he said. “I think probably we need to move in the pandemic, over this winter, maybe towards the end of the winter, to a completely different system of clinically driven testing,” he said. “In other words, testing people who are unwell rather than having a regular testing of those people who are well.” Pollard said that while vaccinating people who have yet to have a Covid jab would make a big difference for intensive care, and booster doses may reduce hospital admissions, vaccinations alone would not be enough to remove pressures on the NHS. “When you look at where the NHS is today, it is incredibly fragile, whether it’s in primary care and secondary care or in social care, and that fragility is only contributed [to] a small amount by Covid,” he said.