The prime minister has raised the prospect of people getting a coronavirus vaccine “booster” jab in the autumn.
Boris Johnson said the move would likely be required as the UK battles the emergence of new variants of COVID-19.
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“I think we’re going to have to get used to the idea of vaccinating and then revaccinating in the autumn, as we come to face these new variants,” he told the Commons during PMQs.
Mr Johnson said a deal with pharmaceutical firm Curevac for 50 million doses would help in developing vaccines to respond “at scale to new variants of the virus”.
It comes after a study suggested that the Oxford/AstraZeneca vaccine may offer limited protection against mild disease caused by the coronavirus variant discovered there.
However, researchers say it will protect against deaths and severe disease.
A US study found that the Pfizer/BioNTech jab is effective against the variant.
Approximately 170 cases of the South Africa variant have been detected in the UK so far.
It carries the E484K mutation which experts have suggested may be better at evading the human immune response.
Oxford vaccine lead researcher Professor Sarah Gilbert said at the weekend that her team was working on an adapted version of the jab to tackle South African variant which could be “available for the autumn”.
Professor Jonathan Van-Tam, one of England’s deputy chief medical officers, has said he is “thinking over the horizon” in preparation for “a long-term resilient vaccine-orientated solution”.
He added: “And that includes the potential for variant vaccines for the autumn.”
Professor Van-Tam said Britons “should not be concerned” that the Oxford/AstraZeneca vaccine could be less effective against the South African variant, adding that case numbers in the UK are “very small” and it is not likely to become more dominant than other strains.
Vaccines minister Nadhim Zahawi told the BBC at the weekend that a booster jab or an annual vaccination in the autumn could be required in the future.
“While it is right and necessary to prepare for the deployment of an updated vaccine, we can take confidence from the current rollout and the protection it will provide all of us against this terrible disease,” he said.
“We need to be aware that even where a vaccine has reduced efficacy in preventing infection there may still be good efficacy against severe disease, hospitalisation, and death. This is vitally important for protecting the healthcare system.”