One in five people eligible for booster jabs are yet to come forward, health chiefs warned as more than one million vaccination slots remain available.
The country’s booster rollout has slowed significantly since peaking in the run-up to Christmas.
On average, fewer than 200,000 doses are being administered daily, compared with more than 800,000 in mid-December.
However, just one in three slots for the current week have now been filled, with 642,000 booked and 1.2 million empty, health officials said.
Prof Stephen Powis, the national medical director of NHS England, said: “There is no excuse not to get your boost of protection with over 1.2 million vaccine appointments up for grabs this week.
“We know that around one fifth of people who have had their first two doses and are eligible for their booster are yet to get protected, but there is no time or reason to delay.
“If you have put it off, now is the time to book and get boosted – it will protect you and ensure you can get maximum protection from omicron as well as protecting those you love.”
In total, around 30 million of 37 million eligible people in England have received a booster vaccine.
