AstraZeneca and Oxford University have published late-stage trial data for their COVID-19 vaccine in the Lancet, the world's oldest medical journal.
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-review journal means that Oxford's methods and how they 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 science is of a high standard, said AstraZeneca's Executive Vice President Mene Pangalos in a press briefing on Tuesday.
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 frontrunners Moderna and Pfizer have announced positive preliminary results and submitted to regulators, but are yet to publish 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's Professor Sarah Gilbert said pointed at additional advantages that could mean it significantly impacts the pandemic overall, including its low price point. AstraZeneca has said it's aiming to have a manufacturing capacity of up to 3 billion doses in 2021.
"We also know that it can be manufactured in large quantities, and at a low price," said Gilbert.
Read more: The UK just approved Pfizer's COVID-19 vaccine. Here are our 5 biggest questions about the shot.
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 are given, but 90% efficacy when the first dose given 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.
Some of the results are pooled from three trial different trials in the UK, Brazil and South Africa. The total number of participants was 23,745 adults, with 11,730 volunteers in a UK trial, 10,002 in Brazil, and 2,013 in South Africa.
The way the data was grouped together and analysed was agreed by regulators in advance, said Director of the Oxford Vaccine Group Professor Andrew Pollard in a press briefing on Tuesday.
The publication also included information about some of the severe side effects associated with the vaccine. The vaccine's safety was monitored for a median of roughly 3 and a half months, in all 23,745 participants.
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 affects the nervous system. 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.
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.
