Watch: WHO says vaccines reduce COVID-19 transmission by 40%
The World Health Organization has warned vaccines alone will not be enough to stop the spread of COVID.
Dr Tedros Adhanom Ghebreyesus, director general of the WHO, said he was concerned there was a “false sense of security” in some countries due to the jabs, amid a surge in infections across Europe.
"Vaccines save lives, but they do not fully prevent COVID-19 transmission,” he said.
“Data suggest that before the arrival of the Delta variant, vaccines reduced transmission by about 60%. With Delta, that has dropped to about 40%".
Dr Tedros added: "In many countries and communities, we are concerned about a false sense of security that vaccines have ended the COVID-19 pandemic, and that people who are vaccinated do not need to take any other precautions".
His warning comes as the UK ramped up its booster vaccine programme.
A total of 50,827,554 first doses of COVID-19 vaccine had been delivered by 23 November, government figures show.
This is a rise of 26,822 on the previous day.
Some 46,208,819 second doses have been delivered, an increase of 22,002.
A combined total of 16,004,629 booster and third doses have also been given, a day-on-day rise of 365,152.
Labour said the vaccination programme has “lost momentum” and warned the UK was not hitting the rate needed to ensure everyone eligible gets a booster by Christmas.
Labour shadow health minister Alex Norris told the Commons: “The vaccination programme has lost momentum over the summer and autumn, and to ensure that everyone eligible gets their booster jab by Christmas we need to be vaccinating half a million people a day and currently we are not near that figure."
Health secretary Sajid Javid said Labour should “not talk down our world-successful vaccination programme” and added the booster rollout is the “most successful” in Europe.
Meanwhile, coronavirus infections broke records in parts of Europe on Wednesday, with the continent once again the epicentre of a pandemic.
Slovakia, the Czech Republic, the Netherlands and Hungary all reported new highs in daily infections as winter started to grip Europe and people increasingly gather indoors in the run-up to Christmas, providing a perfect breeding ground for COVID-19.
Austria has already locked down its population this week for at least 10 days, becoming the first to reimpose such restrictions.
It will also require the whole population to be vaccinated from 1 February.
France will announce new COVID containment measures on Thursday as the infection rate surges nationwide.
Italy is expected to restrict access to some indoor venues for people who have not been vaccinated.
Many German regions have already started to impose tighter rules amid the country's worst COVID surge yet.
Watch: Health Secretary rules out mandatory vaccines