Hours after the UK announced on Tuesday that the most massive vaccination campaign in the country's history had begun in Coventry, central England, all headlines focused on the Pfizer-BioNTech prototype; the Oxford-AstraZeneca duo also wanted to capture their attention at a press conference where they said that the prestigious scientific journal was just about to publish, this afternoon, the first review of full data from a phase III clinical trial of one of the prototypes against covid-19. This is the first time in the course of the vaccine that this occurs, a circumstance that prints a stamp of guarantee on the investigation, since it is an independent analysis.
The efficacy data evaluated by The Lancet are based on results from 11,636 volunteers from the United Kingdom and Brazil. However, only 2,741 people in this subgroup received a lower first dose than the rest. Half of these 2,741 people received the vaccine and the others received a placebo. The safety data are broader and add to the data from the South African trial.
The Lancet thus corroborates that the average efficacy of the prototype is of 70.4%, after making a separate analysis of the data from the two groups of volunteers who were inoculated with the vaccine. Some received two conventional doses 21 days apart. The others received half a dose and then a full dose. In the first group, efficacy was of 62.1%, while in the second group it was of 90%, a fact that still has Andrew Pollard, director of the Oxford Vaccine Group and head of the research process, "intrigued", as he confirmed at the virtual press conference along with other scientific team members and the pharmaceutical company. The university does not plan to conduct another study in the UK with a new subgroup of half-dose plus one volunteers at this time. However, it does intend to complete the collection of data from the volunteers it is already working with.
In this regard, after it was reported that a subgroup of the volunteers in the UK trial were mistakenly given half a dose plus a full dose, the pharmacist said that they needed more data to explain the fact - they had more efficacy with fewer doses - and would possibly conduct a second clinical trial to determine the causes. However, this possibility has finally been ruled out by AstraZeneca, as also confirmed by Mene Pangalos, the company's director of biomedical research. For Pangalos, the results of the half-dose plus one trial are also "intriguing". "But we haven't decided if we will do another one. We will do so soon", he said.
According to both The Lancet's review and the data set that Oxford-AstraZeneca has already sent to different regulators around the world, they hope to get emergency clearance in the coming weeks. What dose distribution will be used when this happens? One and one, or half and one? "It will depend on the decision of the regulators", confirmed Professor Pollard.
Another element highlighted by the scientists who have done the review is that the vaccine is very safe. "No hospitalisations or serious illnesses were observed in the vaccinated groups", writes The Lancet. "Only three of the 23,745 participants over 3.4 months experienced serious adverse events: 1 in the vaccine group, 1 in the control group and 1 not yet assigned to any group. All participants have recovered or are recovering and continue to be tested.
Secondary results, but still to be completed, suggest that the vaccine may also protect against asymptomatic infections: vaccine efficacy is 4% for those given two full doses, and 59% for those given one half and one full dose. Still, the findings need to be confirmed.
So far, none of the vaccines produced in the Western world that have applied for or been granted emergency use authorisation, such as the Oxford, Moderna, Pfizer-BioNTech or Janssen vaccines, have sent their findings for review. Neither have the promoters of the Russian Sputnik V vaccine, which has been in use since Saturday, nor those of the Chinese vaccine, a country that is estimated to have already vaccinated more than a million people.
Regardless of when it receives approval, production of the Oxford-AstraZeneca vaccine has also been disrupted by manufacturing problems. The UK government's vaccine working group has confirmed that only 4 million doses could be delivered, all imported from the Netherlands and Germany. The initial forecast was that up to 30 million, all produced in the UK, would be delivered before the end of 2020.