A single dose of the Oxford-AstraZeneca coronavirus vaccine is 76% effective for up to 90 days after vaccination, a new study out of the U.K. suggests.
University of Oxford researchers published a study Tuesday in Preprints with The Lancet, indicating that the first of the two prescribed doses affords a formidable amount of protection after the 22 days it takes for the body to build up an immune response.
Further, the vaccine seemed to reduce the transmission rate drastically, with a 67% reduction in positive coronavirus tests among the vaccinated subjects, the researchers said.
The study is still being peer-reviewed, but several health experts called the results promising, though not conclusive, reported CNN.
The findings bolstered the reasoning behind an emerging strategy in Britain to vaccinate more people upfront and put off the second shot that the AstraZeneca vaccine requires, in order to inoculate more people, said Dr. Doug Brown, chief executive of the British Society for Immunology, according to CNN. However, experts emphasized that more research is needed.
The study “hints that the Oxford/AstraZeneca vaccine may be effective in stopping people being able to transmit the virus,” he told the U.K.’s Science Media Centre (SMC), according to CNN. “While this would be extremely welcome news, we do need more data before this can be confirmed, and so it’s important that we all still continue to follow social distancing guidance after we have been vaccinated.”
The U.K. government had received pushback for its controversial decision to elongate the time period between shots of the Pfizer-BioNTech vaccine, which has not been tested at intervals of more than three weeks.
The AstraZeneca news comes at a critical juncture, with health care workers in a race against a much more transmissible, and potentially more lethal, variant of SARS-CoV-2. The study did not address the variants, which include others from South Africa and Brazil, but Oxford Vaccine Trial chief investigator Professor Andrew Pollard said data on them could be coming soon.
“These new data provide an important verification of the interim data that was used by more than 25 regulators including the MHRA and EMA to grant the vaccine emergency use authorization,” Pollard said in a statement, referring to the UK’s Medicines & Healthcare products Regulatory Agency and the European Medicines Agency of the EU. “It also supports the policy recommendation made by the Joint Committee on Vaccination and Immunization (JCVI) for a 12-week prime-boost interval, as they look for the optimal approach to roll out, and reassures us that people are protected from 22 days after a single dose of the vaccine.”