Boris Johnson is expected to announce today that the final stage of easing controls in England - pencilled in for June 21 - is to be put on hold for up to four weeks amid a surge in cases of the Delta variant first identified in India.
It means rules ordering the wearing of face masks, limiting groups to six people indoors and 30 outdoors, and keeping nightclubs shut are set to remain in place.
The cap on weddings being attended by only 30 people is expected to be relaxed, but the exact details of what new rules would replace it were still being debated on Sunday night.
People aged 25-29 are now being offered the coronavirus vaccine.
The NHS website for booking Covid vaccinations crashed on June 8 as hundreds of thousands of young people queued to book nearly half a million slots. Health service bosses saw an average of 100,000 vaccine appointments scheduled every hour on the first day of the jab being made available to this age group.
In Wales, booking is already open to all people over the age of 18, while in Northern Ireland for those aged 25 and over.
Under advice from the Joint Committee on Vaccination and Immunisation (JCVI), people under 40 are offered Pfizer or Moderna, rather than AstraZeneca due to the link with rare blood clots.