AstraZeneca, the Anglo-Swedish pharmacist collaborating with the Jenner Institute of Oxford University on a coronavirus vaccine, will conduct a further clinical trial. In statements to Bloomberg, the company's CEO, Pascal Soriot, said that this trial will take place after the accidental discovery by the scientific team led by Professor Sarah Gilbert that the best results have been achieved when half a dose was administered and, three weeks later, a full dose.
"Now that we've found what seems to be a better efficacy, we need to validate it, so we need to do some additional research", Soriot said. It's likely to be an "international study, but it could be faster, because we know the efficacy is high, so we need fewer patients", he added. The development of the new trial is unlikely to prevent the U.K. regulator from ruling on the validity of the vaccine for widespread use in the coming weeks, Soriot said.
Earlier this week AstraZeneca announced that the vaccine was up to 90% effective in preventing covid-19 when administered in the above sequence. Surprisingly, when two full doses were administered, the effectiveness dropped to 62%. For this reason, the message from the company and the laboratory was that the average efficiency was 70%. However, on Wednesday, Oxford University explained in a statement that some of the vials used in the trial did not have the right concentration of the vaccine.
One of the things scientists want to be sure of is that the conclusions reached are not statistical randomization. The branch of the trial that received half a dose, and then a full dose, involved 2,741 people, while the branch that received two doses involved 8,895 volunteers.
Doubts in the United States
Professor Andrew Pollard, director of the Oxford Vaccine Group, has said that the 90% efficacy finding has already met the "necessary statistical tests required by regulators. But the scientific director of the United States' Operation Warp Speed, the programme to administer vaccines for the entire country, has raised concerns about the data reporting methodology. Moncef Slaoui said, speaking to a group of journalists on Wednesday after learning of the Oxford University announcement, that the half-dose plus one regimen had only been inoculated in adults under 55. It is generally known that older people have more problems in developing immunity after a vaccine has been given.
Peter Openshaw, professor of experimental medicine at the Imperial College of London, believes that if it is confirmed that only those under 55 had reached 90% effectiveness after one and a half doses, "this could mean that we have no information about this in older adults". Nevertheless, AstraZeneca itself, referring to data from the second phase of the clinical trial, already stated last week that the prototype provided "strong" immunity in people over 65.
Menelas Pangalos, head of biopharmaceutical research and development at AstraZeneca, also reported that the discovery of the efficacy of a half-dose plus a full dose was made after a mistake was made by a contractor developing the trial. In any case, the regulators were immediately informed - one of the characteristics of all trials being conducted with coronavirus vaccine is that information flows in streams and it is not necessary to wait for it to be submitted at the end of the study - and agreed to continue testing the vaccine at the error dose ratio. Speaking to The New York Times, Pangalos said that "it could end up being a very useful error".
The Oxford vaccine data was released days after the provisional results from Pfizer and Moderna were known. According to their own assessments, they were 95% and 94.5%, respectively. On Thursday, AstraZeneca's shares on the London Stock Exchange fell by 0.7%.