(Adds quotes from first person vaccinated and first vaccinator)
LONDON, Dec 8 (Reuters) - The first person in the world to be given a fully-tested COVID-19 vaccine, 91-year-old Briton Margaret Keenan, urged people on Wednesday to get vaccinated, one year on from her shot.
Keenan described receiving the Pfizer-BioNTech COVID-19 vaccine on Dec. 8 2020 as the "best thing that has ever happened".
"It was wonderful. I cannot believe it now, what happened at the time... I'm so happy I got the jab," Keenan, known to friends as Maggie, said in a broadcast clip to mark the anniversary.
"I encourage everyone to have it."
Prime Minister Boris Johnson has highlighted Britain's early success in rolling out COVID-19 vaccines and said it is why he was able to reopen England's economy in July.
He is now urging officials to scale up the country's ongoing booster programme to a similar level as the initial rollout in light of concern over the new Omicron variant, which has also seen him reintroduce some mask mandates and travel restrictions.
"Vaccines remain our first and best line of defence against the virus," Johnson said.
Britain has now given nearly 120 million doses of COVID-19 vaccine to its population of 67 million, either as first doses, second doses or as boosters.
Scientists are concerned that Omicron might be more transmissible than the currently dominant Delta variant and have mutations associated with lower vaccine effectiveness.
Health Secretary Sajid Javid has said that boosters should continue to offer good protection against severe disease even if shots are less effective against Omicron than previous variants.
May Parsons, the nurse who vaccinated Keenan, said a lot of people now seriously ill in her COVID-19 wards are unvaccinated.
"If you're unvaccinated, there is still a chance (to get a shot)," Parsons said. "It's not too late."
(Reporting by Alistair Smout; editing by Mark Heinrich and Philippa Fletcher)