(Bloomberg) — A Covid-19 vaccine developed by the University of Oxford and AstraZeneca Plc prevented a majority of people from getting the disease in a large trial, another promising development in the quest to end the pandemic.
The vaccine stopped an average of 70% of participants from falling ill, an early analysis of the data show. That’s below the high bar set by Pfizer Inc. and Moderna Inc., but effectiveness rose to 90% for one of two dosing regimes, using half a dose followed by a full one later.
“We see a lot of merit in this regimen and we will now start discussions with regulators into incorporating this dose combination for further clinical investigation,” an Astra spokesman said.
#COVID19. Interim data show the #OxfordVaccine is 70.4% effective, & tests on two dose regimens show that it could be 90%, moving us one step closer to supplying it at low cost around the world>> https://t.co/fnHnKSqftT pic.twitter.com/2KYXPxFNz1
— University of Oxford (@UniofOxford) November 23, 2020
U.S. Astra shares fell 1.5% early Monday in London.
Despite the apparently lower efficacy than shots from Pfizer and Moderna, which each prevented about 95% of cases, the British vaccine has some advantages when it comes to distribution. While the other two vaccines have to be stored frozen, the Astra-Oxford jab can be kept at refrigerator temperature, which would make it easier to transport and store globally, particularly in lower and middle-income countries. It also comes at a lower cost.
The findings were reviewed after 131 trial participants contracted Covid-19. Among those who received the vaccine, there were no severe cases of Covid-19 in the trial and no participants were hospitalized.
The differing results of the two dosing regimens, with a less effective two-shot system preventing 62% of cases, may leave questions about the best way to give the AstraZeneca shot. Analysts at Barclays Plc had put consensus expectations for what would be deemed a success from AstraZeneca at 70% to 90%, following conversations with investors in Europe and the U.S.
AstraZeneca said it will immediately prepare to submit data to authorities around the world that have a framework in place for early approval. The company said it will seek an emergency use listing from the World Health Organization for an accelerated pathway to vaccine availability in low-income countries.
The more effective of the two trial regimes, starting with half a dose, could provide advantages, according to Oxford Professor Andrew Pollard.
“It means we will have a lot more doses to distribute if that way of vaccinating was approved,” he said on BBC radio. “Those who got that regimen with higher protection, there’s a suggestion that it was also able to reduce asymptomatic infection. If that’s right, that means that we might be able to hold the virus in its tracks and stop it from transmitting between people.”
The results were based on trials in the U.K. and Brazil. A much larger U.S. trial, which will be key for approval there, is currently using the two-dose regimen, which the results so far show to be less effective. In light of the different outcomes for the dosing regimes, investigators are looking at making changes to other trials and discussing this with regulators.
Vaccine developers will not know how long any protection lasts for a number of months as they monitor antibody levels to see how quickly or not they fade. U.K. and European Union regulators are conducting accelerated reviews of the results from both Astra and Pfizer, which has applied for an emergency use authorization in the U.S.
Astra and Oxford have been among the fastest-moving vaccine developers from early on in the pandemic. After years spent working on a vaccine against Covid’s relation Middle East Respiratory Syndrome, Oxford’s scientists had an advantage that allowed them to move quickly to create a shot.
(Updates with AstraZeneca shares, Pollard comments)
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