Coronavirus booster jabs give more than 90% protection against symptomatic infection in adults aged over 50, according to a study by the UK Health Security Agency (UKHSA).
In September the Joint Committee on Vaccination and Immunisation (JCVI) recommended that boosters be rolled out to eligible groups including adults 50 years and above, and on Monday it extended this advice to adults over 40.
The findings of the new research show that two weeks after receiving a Pfizer booster dose, protection against symptomatic infection was 93.1% in those who had initially received Oxford/AstraZeneca, and 94.0% for Pfizer/BioNTech.
Meanwhile, data from Israel indicates booster jabs could prevent Covid-19 deaths through the winter and over Christmas.
After two doses of either vaccine, effectiveness against symptomatic disease appears to wane over time.
While experts say vaccine effectiveness against severe outcomes, such as hospital admission, remains high for several months after completing the primary course, researchers have seen greater waning in older adults and those with underlying medical conditions compared with young, healthy adults.
Dr Mary Ramsay, head of immunisation at the UKHSA, said: “Our findings demonstrate the protection provided by the booster dose against
symptomatic infection in those at highest risk from developing severe Covid-19.
“We know that in older age groups, protection from the first two vaccines is beginning to wear off, leaving millions that need extra protection as we head into winter.
“That is why it is critical that you come forward for your booster as soon as you become eligible so we can drive down hospitalisations and deaths over the winter.”
Professor Wei Shen Lim, chair of Covid-19 immunisation for the JCVI, told a televised Downing Street briefing on Monday morning that boosters “markedly” strengthen protection against coronavirus.
He said: “Whilst we don’t yet have data on protection against hospitalisation and unfortunately people dying from Covid-19, we can expect protection to be even higher than that figure of 93% because that’s what happened so far in the vaccine programme.
“So overall we are advising now that the data tells that the booster dose markedly strengthens existing protection and will extend the duration of that protection against serious disease.
“We therefore urge people who are eligible for a booster to step and have your booster and maximise your protection.”
Deputy chief medical officer for England Professor Jonathan Van-Tam said figures from Israel show booster jabs could prevent Covid-19 deaths over Christmas and beyond.
Speaking at a press briefing, he said: “They’re showing that in people aged over 60 in Israel, after a messenger RNA booster, and compared with simply having received the first two doses of Pfizer – in the case of Israel three to four weeks apart – they are observing a tenfold reduction against all Covid infections, an 18.7-fold reduction against hospitalisations, and a 14.7-fold reduction against mortality, and that’s on top of the initial course of Pfizer.
“So I believe therefore that if the booster programme is successful, and with very high uptake, we can massively reduce the worry about hospitalisation and death due to Covid at Christmas, and for the rest of this winter.”