Oxford University's candidate coronavirus vaccine is 70.4% effective, according to interim data from Phase Three trials.
The efficacy depended on the dosing regimen, the university said in a statement, with the vaccine, which was developed with pharmaceutical company AstraZeneca, becoming 90% effective if administered at a half dose and then at a full dose and 62% effective if administered in two full doses.
There were no hospitalised or severe cases of the virus among those who received the vaccine, the university said in a statement.
A total of 131 participants came down with COVID-19 in the trial. The phase three trials include more than 23,000 participants in the UK and Brazil.
"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 regimen is used, more people could be vaccinated with planned vaccine supply," said Professor Andrew Pollard, the chief investigator of the Oxford Vaccine Group.
It comes after the team announced last week that Phase 2 trials in healthy older adults showed the candidate vaccine is safe and provokes an immune response.
The phase 2 trial, which involved 560 adults including 240 over the age of 70, found that the vaccine causes few side effects and induces immune responses in both parts of the immune system in all age groups.
"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," said Pascal Soriot, the Chief Executive Officer of pharmaceutical company AstraZeneca.
The news from Oxford comes after results showed that vaccines developed by Pfizer and Moderna were 95% effective.
The vaccine developed by Pfizer and BioNTech was 94% effective in adults over the age of 65, who are more at risk for severe illness.
This was viewed as an outcome that was much better than anticipated by experts who now say that a vaccine could be made available by the end of 2020 for healthcare workers and those who are more vulnerable to the virus.
European Commission President Ursula von der Leyen said that vaccines could be approved in the EU before the end of the year.
The Oxford vaccine is made from a weakened cold virus that was genetically changed. It can be stored in a regular refrigerator instead of at ultra-cold temperatures like the Pfizer vaccine, making it easier to store.
The vaccine is currently being manufactured in 10 countries to support global access.
Experts say that distributing an effective and safe vaccine is one of the best tools available to help end the COVID-19 pandemic.