A new study suggests the Oxford-AstraZeneca COVID-19 vaccine cuts transmission of the virus by two-thirds and prevents severe disease. Oxford University released the results on Wednesday.

The research has not yet been peer reviewed, meaning other scientists have not examined it. But, Britain's Health Secretary Matt Hancock told broadcaster Sky News the findings are "very good news."

Hancock said the latest results showed the AstraZeneca vaccine slows spread of the virus by about 66 percent. He added that the study also found the vaccine injections were highly protective after a single dose.

The head of research and development for AstraZeneca, Mene Pangalos, told reporters no patients had experienced severe disease or hospitalization three weeks after receiving a first dose. The effectiveness of the vaccine appeared to increase up to 12 weeks after the first shot, he added.

The European Medicines Agency approved the vaccine for adults of all ages last week. However, most of the subjects involved in the AstraZeneca vaccine trials were under 55 years old.

Italy and Belgium have approved use of the vaccine in adults under 55. Belgium's health minister said there was not enough information available "to be sure to say that it is good" for older individuals.

Poland is permitting use in adults up to age 60. And Germany, Italy, and Sweden have approved its use for people 18 to 65 years old.

The new Oxford study found that those who were given a single dose of the vaccine were 67 percent less likely to test positive for COVID-19. This suggests the possibility "for a substantial reduction in transmission," it said.

The study provides support for Britain's campaign to treat as many high-risk groups as possible with a first dose of the vaccine. The country is providing second injections 12 weeks after the first. It argues that the delay will help protect more people quickly. Some experts disagree.

The other vaccine already in use in Britain is from Pfizer-BioNTech. That medicine is advised for use in two doses given three weeks apart. But, Health Secretary Hancock said Wednesday that Britain believes a 12-week period is the right plan for both vaccines.

The Oxford study involved more than 17,000 people in Britain, Brazil and South Africa.

I'm Bryan Lynn.

The Associated Press, Agence France-Presse and VOA News reported on this story. Bryan Lynn adapted the reports for Learning English. Caty Weaver was the editor.