- The UK will begin administering booster shots for over-50s.
- UK officials have said vaccines have saved at least 112 000 lives.
- The booster shots will start with those most vulnerable.
Britain will begin a broad-based Covid-19 vaccine booster programme for those older and more vulnerable adults soon as Prime Minister Boris Johnson's government relies on vaccines rather than further lockdowns to navigate a "bumpy" winter.
British officials said that Covid-19 vaccines have saved more than 112 000 lives and averted 24 million cases of the disease as they recommended all vulnerable people, frontline health staff and those aged over 50 be offered a booster shot, starting with the oldest and most vulnerable.
Johnson hopes that the booster programme, which is being undertaken on a precautionary basis without firm evidence about its likely impact, will mean that hospitals can bear the burden of winter without the need for another lockdown.
But health minister Sajid Javid said a "Plan B", involving mandatory vaccine certificates in some settings, mandatory mask wearing and asking people to work from home, was being held in reserve. Vaccinations for health workers were likely to be made compulsory, he said.
"Booster doses are an important way of keeping the virus under control for the long term," Javid told parliament, saying the programme would begin next week.
"We have prepared a plan B of contingency measures that we can call upon only if they are needed and supported by the data."
The government's 30-page winter strategy cautioned that the plan B could be implemented at short notice.
The Joint Committee on Vaccination and Immunisation's (JVCI) recommendation of a third dose six months after a second shot, paves the way for a broad revaccination programme in Britain, which has one of the world's highest death tolls from Covid-19.
Britain is also currently recording the second highest number of new infections after the United States.
A booster programme is being launched in the United States this month, with the likes of Israel, Ireland and Italy also moving ahead with booster shots.
British officials said protection from two doses of vaccine beyond 6 months was uncertain and that boosters would prevent illness and deaths from Covida-19 over the winter, but did not say whether the extra shots would lower transmission rates.
"We're not past the pandemic. We know this winter could quite possibly be bumpy at times," England's Deputy Chief Medical Officer Jonathan Van-Tam told reporters.
"It's better to be pre-emptive and to be prepared and plan for the worst possibilities."
Britain has officially recorded 134 000 Covid-19 deaths, and more than 7 million cases. So far 44 million people have had two vaccine doses, 81% of those aged over 16. On Monday, the government said those aged 12 to 15 would also be offered shots.
Johnson scrapped the last coronavirus restrictions in England in July, citing the more favourable conditions of the school summer holidays as he eyed what he characterised as a "return to normal".
"The pandemic is far from over, but thanks to our phenomenal vaccine programme, new treatments and testing we are able to live with the virus without significant restrictions on our freedoms," Johnson said in a statement.
The JCVI said its preference was that the Pfizer vaccine was used for the booster dose, or alternatively a half-dose of a Moderna shot. Britain ordered 60 million additional Pfizer doses for the booster programme in April.
Professor Wei Shen Lim, chair for Covid-19 immunisation on the JCVI, said their advice for a booster dose did not imply that there would be a requirement for a shot every six months.
He also said not everyone under 50 years old would require another shot.
The British recommendation comes after some leading scientists, including from the U.S. Food and Drug Administration and World Health Organisation, wrote in Monday's Lancet medical journal that Covid boosters were not yet needed for the general population.