ScienceAstraZeneca is the first COVID-19 vaccine-maker to publish results from late-stage trials in a peer-reviewed journal.- The results, published in the Lancet on Tuesday, suggest the vaccine's efficacy is 70%, on average.
- The data confirmed preliminary results announced on November 23.
- The shot hasn't been signed off by regulators, but the data has been submitted and is under review.
- Pfizer and Moderna have announced positive preliminary results, but have not yet published in a scientific journal.
- Oxford's vaccine trials can now be scrutinized, but questions remain, including how the shots work in elderly people, and why administering a lower dose first seems to be more effective.
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The vaccine is highly effective at preventing symptomatic COVID-19, and generally well tolerated, the results published on Tuesday showed.
Publishing late-stage trial data in a peer-reviewed journal means that Oxford's methods and how scientists crunched the numbers can be fully scrutinized by experts and the public. The data has already been submitted to certain regulators worldwide.
It's important to publish in a high quality journal so that others can confirm that the quality of the data and the
He said that publishing the results is not to "influence" the regulator.
"The regulator will make their own decision based on all the data we provide them," Pangalos added.
Vaccine front-runners Moderna and Pfizer have announced positive preliminary results and submitted to regulators, but are yet to publish them in a peer-reviewed paper. Pfizer's vaccine has been approved in the UK, and rollout started on Tuesday.
The results suggest that Oxford's vaccine is highly effective and safe. However, University of Oxford Professor Sarah Gilbert pointed at additional advantages that could mean it significantly impacts the pandemic overall, including its low price point.
"We also know that it can be manufactured in large quantities, and at a low price," said Gilbert.
AstraZeneca has said it's aiming to have a manufacturing capacity of up to 3 billion doses in 2021.
Read more: The UK just approved Pfizer's COVID-19 vaccine. Here are our 5 biggest questions about the shot.
The published results confirmed the vaccine is 70% effective on average
The results confirmed a preliminary announcement that the vaccine was 70% effective, on average, at protecting people from catching COVID-19, and developing symptoms. The vaccine worked differently at different doses, with 62% efficacy when two full doses were given, but 90% efficacy when the first dose was halved.
So far there haven't been any hospitalizations or severe disease reported by volunteers who have received Oxford's vaccine, according to the data in the Lancet.
Pangolos said that the results were compelling.
"We clearly have an effective vaccine that meets the regulatory standard for approval around the world," he said.
It is statistically possible that the different dose regimens could turn out to have similar efficacy, the data published in The Lancet shows, because the 62% and 90% figures are estimates. The true numbers could be higher or lower, and additional data from ongoing trials could pull the numbers one way or another.
"Statistically it's perfectly within range that actually it could all settle out to about 70%," Dr. Peter Openshaw, professor of experimental medicine at Imperial College London, told Business Insider on Tuesday.
The data on how well the vaccine works comes from two ongoing trials in the UK and Brazil, involving 11,636 of the 23,848 adult participants enrolled. The 11,636 is made up of 7548 volunteers from the UK trial, and 4088 from the Brazil trial.
The safety data comes from results pooled from all four trials in the UK, Brazil and South Africa.
The way the data was grouped together and analysed was agreed upon by regulators in advance, said Director of the Oxford Vaccine Group Professor Andrew Pollard in a press briefing on Tuesday.
The vaccine's safety was monitored for a median of roughly 3 and a half months.
There was one adverse event possibly thought to be related to the COVID-19 vaccine, including a case of transverse myelitis, inflammation of the spinal cord that typically causes weakness of the arms or legs, pain, unusual sensations like tingling, and/or bladder or bowel dysfunction. There was also a case of severe fever reported by a volunteer in South Africa, but it's not yet known whether they had received the vaccine or not. Neither of these participants have been withdrawn from the trials.
The results leave some unanswered questions
While the results are positive, and another vaccine development milestone has been achieved, the trials are ongoing and questions will still remain. For example how well the vaccine works in different age groups, and why half a dose at the start seems to have higher efficacy results.
Professor Pollard who is the lead author of the study said that when they analysed the data by age to look into this, there didn't appear to be an "age-phenomenon".
He referred to the results with different doses as "intriguing".
However, there was no further definitive information from the scientists as to why it is the case. "It's important we do generate more data over time," he said.
More data on subgroups like the elderly or the different dose regimens are expected in the future, Gilbert said.
The team hasn't confirmed how they're planning to investigate it further.
"We will decide in due course," said Pangalos.