Also, 16 and 17 year olds should get a second dose of vaccine according to official UK advice.
All over 40s should be offered a third dose of a Covid vaccine, according to the UK government’s vaccine advisors.
The move would top up protection and help limit the spread of the virus over winter.
Evidence suggests the chance of testing positive for Covid falls by more than 80% two weeks after a booster.
The Joint Committee on Vaccination and Immunisation also said 16 and 17 year olds, who were initially offered only a single dose, should now get a second.
So far, 12.6 million people have had a booster dose. They have been given to the over 50s, front-line medical staff and people with health conditions that put them at greater risk.
People aged 40-49 years old will be topped up with either Pfizer or a half dose of the Moderna jab. This should be offered six months after the second dose.
The UK’s drug safety regulator – the Medicines and Healthcare products Regulatory Agency (MHRA) – said the booster doses were safe and side-effects were either a sore arm or flu-like symptoms.
Dr June Raine, regulator’s chief executive, said: “We welcome today’s announcement by the JCVI, on the extension of the booster campaign to 40-49 year olds. This further strengthens our ability to ensure people are protected against COVID-19 and saves lives.
“Our proactive monitoring of the safety of booster doses does not raise any new concerns.”
The amount of protective given by the vaccines does fall after the second the dose.
Prof Neil Ferguson said there was “no reason” not to give boosters to younger age groups and it “could make quite a big difference to driving down transmission to low levels”.
Children – aged 16 and 17 – have only been offered one dose of a Covid vaccine so far. They will now get a second dose – at least 12 weeks after their first.
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