Sajid Javid has warned face coverings and work from home advice could return this winter, as he unveiled a five point plan to protect the nation against a surge in Covid cases.
The contingency plans, which could also see people ordered to show their vaccination status, will only be activated if there is “unsustainable” pressure on the NHS in England, Mr Javid said.
Covid cases have averaged between 30,000 and 40,000 for the past few weeks, but there are fears of an autumn surge driven by more people mixing indoors or by a drop in levels of immunity provided by vaccines.
Read more: Five major Covid changes that could be seen including vaccines for children
Mr Javid, speaking in the Commons, said in the coming weeks there would be moves to strengthen the vaccine uptake, a booster campaign, regular testing for frontline workers, extra cash for the NHS and continued financial support for those who have to self isolate.
But the Health Secretary warned he needed to keep a "plan B" in reserve.
He said: "The plan before the House today is our plan A, a comprehensive plan to steer this country through autumn and winter.
"But we've seen how quickly this virus can adapt and change so we have prepared a plan B of contingency measures that we can call upon only if they are needed and supported by the data to prevent unsustainable pressure on the NHS.
"These measures would be communicating clearly and urgently to the public the need for caution., legally mandating face coverings in certain settings and whilst we're not going ahead with mandatory vaccine COVID status certification now, we'll be holding that power in reserve.
"As well as these three steps, we would consider a further measure of asking people to work from home if they can for a limited time, if that is supported by the data."
One element of "plan B" could see mandatory vaccine passports required to enter nightclubs; indoor venues with 500 or more attendees likely to be in close proximity to others, such as music concerts; outdoor settings with 4,000 or more people, such as festivals; and any settings with 10,000 or more people, such as sports events.
The announcement came as England’s deputy chief medical officer Professor Jonathan Van-Tam warned of a “bumpy” winter ahead.
At a Downing Street press conference, he said vaccines had been “incredibly successful” and had so far prevented an estimated 24 million Covid-19 cases and 112,000 deaths.
“But we also know that this pandemic is still active. We are not past the pandemic, we are in an active phase still.
“We know that this winter could quite possibly be bumpy at times and we know that other respiratory viruses such as flu and RSV are highly likely to make their returns.”
Prof Van-Tam said booster vaccines would be offered to people aged 50 and over, those in care homes and frontline health and social care workers.
All those who are clinically extremely vulnerable and anyone aged 16 to 65 in an at-risk group group for Covid (who were in priority groups one to nine during the initial vaccine rollout) will also be eligible for a jab.
