Labour is calling on the government to bring in its Plan B measures to tackle Covid in England, including advice to work from home and compulsory masks.
Shadow chancellor Rachel Reeves also told the BBC the vaccine programme was “stalling” and needed to work better.
But Chancellor Rishi Sunak said the data did not currently suggest “immediately moving to Plan B”.
Plan B, which aims to protect the NHS from “unsustainable pressure”, also includes mandatory Covid passports.
Plan A, which is currently in place, involves offering booster jabs to the most vulnerable, a single dose to healthy 12 to 15-year-olds and encouraging unvaccinated people to get jabbed.
Ms Reeves said Labour “would follow the science”, adding that the government’s Scientific Advisory Group for Emergencies (Sage) had said some aspects of Plan B, such as wearing masks on public transport and in shops, as well as working from home more flexibly, should be introduced.
“I think the first thing is the government have got to do more to make Plan A work,” she told BBC One’s Andrew Marr Show.
“If the scientists are saying work from home and masks, we should do that. So get A working better because the vaccination programme has been stalling, introduce those parts of Plan B.
“But there are also things not in A or B that need to be done, like paying statutory sick pay from day one and also better ventilation in public spaces.”
Asked whether Plan B should be introduced now, she said: “Yes, but let’s not let the government off the hook with Plan A either.”
Appearing on the same programme, Mr Sunak was also asked whether it was time to bring in Plan B.
“We’re monitoring everything, but at the moment the data does not suggest that we should be immediately moving to Plan B, but of course we will keep an eye on that and the plans are ready,” he said.
The chancellor also said reintroducing the furlough scheme was “not on the cards because we don’t envisage having to impose significant economic restrictions in the way that we had to over the last year”.
He added that the vaccine rollout was the “first line of defence” and the booster campaign was the best way to protect people through the winter.