Those behind the vaccine insist it has already met the ‘necessary statistical evidence’ (Picture: PA/AP)
A US health official has claimed that the dose of the Oxford vaccine shown to be 90% effective was only tested in people aged 55 and under.
Moncef Slaoui, who heads the programme to supply America with vaccines, said that the half-dose regime, which was discovered by accident, was only given to younger age groups.
But British scientists have lined up to defend the research, with Oxford University’s partners AstraZeneca saying they are likely to hold another global clinical trial, but do not expect that to hold up the jab from being given the green light.
Mr Slaoui, the scientific head of the US’s Operation Warp Speed, suggested that most of the people in the initial trial received a placebo or two full doses, and the effectiveness was 62%, Bloomberg reported. That group included people who were older than 55, unlike the 90% effective group which only gave a half dose before a full-dose booster.
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Scientists across the globe are hoping to find vaccines that work in older people, who are most at risk from Covid-19.
Oxford’s overall efficacy from two different dosing regimes in a phase three trial was announced last week at a combined figure of 70%.
A half dose followed by a full dose was found to be 90% effective according to a subset of data, but efficacy was 62% for people given two full doses.
Results from an earlier phase two study of the vaccine published in The Lancet medical journal showed the vaccine produced a strong response in all age groups.
Scientists were working on the Oxford vaccine at speed (Picture: PA)
Professor Andrew Pollard, director of the Oxford Vaccine Group, said last week that the 90% effectiveness finding had already met the ‘necessary statistical evidence as required by regulators’.
He said further evidence will probably be available next month but it is ‘a highly significant result even with the numbers that we have’.
The 90% efficacy was based on a dosing regime given to 2,741 people.
The other regime, using two doses, involved 8,895 people.
Neither AstraZeneca nor Oxford initially disclosed that the 90% figure was based on adults aged 55 and under.
The Moderna, Pfizer/BioNTech and Sputnik vaccines are also in development (Picture: PA)
It comes as some US scientists have questioned a lack of detail in the results put out last week by AstraZeneca and Oxford.
The New York Times reported that AstraZeneca’s Menelas Pangalos has defended the company’s handling of testing and its public disclosures.
Asked why AstraZeneca had not shared the information with the public, he said: ‘I think the best way of reflecting the results is in a peer-reviewed scientific journal, not in a newspaper.’
Some experts have also raised questions about the use of two differently designed clinical trials in Britain and Brazil, and pooling analysis from both.
They also say it is unclear how many coronavirus cases were found in each group of the trial.
John Moore, a professor of microbiology and immunology at Weill Cornell Medical College, told the New York Times: ‘The press release raised more questions than it answered.’
In an interview with the New York Times, Mr Pangalos said the half-dose finding ‘could end up being quite a useful mistake’.
He added: ‘It wasn’t putting anyone in danger. It was a dosing error. Everyone was moving very fast.
‘We corrected the mistake and continued on with the study, with no changes to the study, and agreed with the regulator to include those patients in the analysis of the study as well.’
Oxford University said it would not comment ahead of the data appearing in a peer-reviewed publication.
In a Downing Street briefing this evening, England’s chief medical officer Professor Chris Whitty said the ‘excellent’ Medicines and Healthcare products Regulatory Agency (MHRA) would assess all data ahead of its potential roll out to the UK and added that ‘there is always scientific debate about everything’.
Mr Pangalos said the company is planning a global trial with thousands of people to compare the two dosing regimes.
The Oxford vaccine is much cheaper and can be stored far more easily than vaccines from Pfizer/BioNTech and Moderna, which require very cold temperatures. Russia also claims its Sputnik vaccine is 95% effective.
In an interview with the PA news agency last week, Tom Keith-Roach, president of AstraZeneca UK, said the UK could receive 19 million doses of the jab by the end of the year if it is approved.
He also backed the 90% efficacy result, suggesting it was based on statistically significant data.
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