Boris Johnson and health experts defend AstraZeneca jab as Germany moves to limit Covid vaccine to under-65s

"The risk of severe disease and death increase exponentially with age - the priority is to vaccinate as many vulnerable people as possible with either vaccine, to protect more people and save more lives."

Oxford University, which partnered with AstraZeneca to develop the vaccine, has said its jab offers high protection against severe disease and prevents people needing to go to hospital.

AstraZeneca said: "The latest analyses of clinical trial data for the AstraZeneca/Oxford Covid-19 vaccine support efficacy in the over 65 years age group.

"We await a regulatory decision on the vaccine by the EMA in the coming days."

Professor Andrew Pollard, director of the Oxford Vaccine Group, pointed to the MHRA's report, which said there were two cases of Covid-19 in the over-65s.

The MHRA said: "There is limited information available on efficacy in participants aged 65 or over, although there is nothing to suggest lack of protection."

A Phase 3 Lancet study published in December said older age groups had been recruited later into the study so "efficacy data in these cohorts are currently limited by the small number of cases, but additional data will be available in future analyses".

In that particular analysis, only 12 per cent of people given two doses of the vaccine in the UK arm of the trial (285 out of 2,377) were aged 56 to 69, while nine per cent (213) were over 70.

Some 12 per cent of people in the control group (given a dummy vaccine) were also aged 56 to 69 while nine per cent were over 70.

Older people made up similar proportions in the Brazilian section of the trial, which was made up of 4,088 people.

Previous work published in November included findings for 560 people.

Of these, 160 were aged 18 to 55, 160 were aged 56 to 69, and 240 were 70 or older.

Those results found that all age groups, including older people, had an immune response to the vaccine after two doses.

Earlier this week, a report in German business daily newspaper Handelsblatt said AstraZeneca's vaccine was thought to be only eight per cent effective among the over-65s.

AstraZeneca and the vaccines minister Nadhim Zahawi dismissed the report as "incorrect" and "untrue".

Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said an attempt to work out the exact efficacy in older age groups based on extremely small numbers was "so uncertain as to be meaningless".

He added: "There is no reason at all for anyone in the UK or elsewhere to think that this Oxford/AstraZeneca vaccine is ineffective at any age.

"Its ability to be delivered to people in GP surgeries and care homes makes it a vital component in the attempts to reduce hospitalisation and deaths, especially in the elderly."

Professor Jim Naismith, director of the Rosalind Franklin Institute at the University of Oxford, said German scientists "have not said the vaccine is ineffective for over-65s".

He added: "Scientists often disagree about how much evidence is needed for any new advance and there is always more data to be secured.

"Normally this all happens out of sight of the glare of the media and not in a pandemic but such debates are an important part of the scientific process that is familiar to anyone who has ever been through peer review."