A COVID-19 vaccine developed by the University of Oxford and AstraZeneca plc prevented about 70% of trial participants from getting the disease, the developers said Monday.
AstraZeneca shares were down about 1.08% at $55.30 in Monday premarket trading on the Nasdaq exchange.
AstraZeneca said there were no serious safety events and it was "well tolerated" across different dosing regimens. Late-stage clinical trials of the vaccine are continuing in the U.S. following a pause that spanned most of September and October.
"These findings show that we have an effective vaccine that will save many lives. Excitingly, we've found that one of our dosing regimens may be around 90% effective and if this dosing regime is used, more people could be vaccinated with planned vaccine supply," Chief Investigator of the Oxford Vaccine Trial at Oxford Professor Andrew Pollard said.
AstraZeneca said it would seek emergency-use authorization from the World Health Organization to distribute the vaccine in low-income countries and prepare regulatory submissions to authorities in countries that have early-approval programs.
However, the treatment's performance isn't as good as the results set by Pfizer Inc. and Moderna Inc., according to initial results of a large trial.
The University of Oxford and AstraZeneca vaccine stopped an average of 70% of participants in a study from falling ill, an early analysis of the data shows. The findings were reviewed after 131 trial participants contracted COVID-19, and are based on two different dosing regimens.
British pharmaceutical company AstraZeneca said an interim analysis of clinical trials showed its coronavirus vaccine has an average efficacy of 70% in protecting against the virus.
Nevertheless, AstraZeneca said its treatment might be around 90% effective under one dosing regimen.
It is hoped a COVID vaccine could help to bring an end to the coronavirus pandemic that has claimed more than 1.3 million lives.
This is an "important milestone" in the fight against the health crisis, AstraZeneca chief executive Pascal Soriot said.
"This vaccine's efficacy and safety confirm that it will be highly effective against COVID-19 and will have an immediate impact on this public health emergency," Soriot said. "Furthermore, the vaccine's simple supply chain and our no-profit pledge and commitment to broad, equitable and timely access means it will be affordable and globally available, supplying hundreds of millions of doses on approval."
British Prime Minister Boris Johnson on Monday hailed the "fantastic" news that AstraZeneca's vaccine might be up to 90% effective - but said it still would require safety checks.
"Incredibly exciting news the Oxford vaccine has proved so effective in trials," Johnson said on Twitter. "There are still further safety checks ahead, but these are fantastic results."
Health Secretary Matt Hancock said: "We are on the cusp of a huge scientific breakthrough that could protect millions of lives." It was "fantastic news" that Monday's data showed that a COVID-19 vaccine developed by AstraZeneca with Oxford University could be up to 90% effective. "These figures...show that the vaccine in the right dosage can be up to 90% effective," he told Sky News.
"We've got 100 million doses on order and should all that go well, the bulk of the rollout will be in the new year."
The results are based on interim analysis of trials in the U.K. and Brazil.
