The proposal will only be introduced if the country faces a difficult winter with rising Covid cases in the colder months, the Government said.
But ministers on Monday night insisted the Government needed to be prepared to “act swiftly” and adopt measures such as vaccine passports “at short notice” if there were “unsustainable pressures” on the NHS as a result of the Covid-19 pandemic.
Maggie Throup, the new minister for vaccine deployment, said: “While we are totally confident the careful steps we are taking will help rule out the need for mandatory vaccine certificates, we need to be prepared for all scenarios.
“We know these kinds of contingency plans will only work if businesses and the public get to have their say and I’m urging everyone who could have to use certification: give us your views, give us your ideas.”
Under the plan, only double-vaccinated people would be certified by the passports. Negative coronavirus tests and proof of natural immunity after recently recovering from the virus would no longer be permitted.
Sajid Javid had announced he was scrapping plans to introduce vaccine passports, requiring members of the public to show proof of double-vaccine status.
The Health Secretary announced the Government U-turn just weeks ago, following a backlash from Tory MPs.
The Plan B proposals draw on the findings of a review into vaccine passports earlier this year, which concluded that certification could help keep events going and businesses open.
They set out how all visitors, aged 18 and over, to certain events could be required to be fully vaccinated.
The events listed are all nightclubs, and other venues open after 1am with alcohol, music, and dancing and indoor events with 500 or more attendees where they are likely to stand and mix to a significant degree, or move around during the event, such as music venues or large receptions.
The plan also includes outdoor, crowded settings with 4,000 or more attendees where they are likely to stand, or move around during the event, such as festivals, and any settings with 10,000 or more people, such as large sports and music stadia.
Staff aged 18 or over in settings could also be required to test regularly if they are not fully vaccinated or exempt.
Industry and the public have been given until October 11 to respond to the planned vaccine passports, which would be mandatory for all adults over 18 attending the prescribed venues, and would require legislation.