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 booster dose, protection against symptomatic infection was 93.1% in those who had initially received Oxford/AstraZeneca, and 94.0% for Pfizer/BioNTech.
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.”