University of Oxford's COVID-19 Vaccine Shows Sustained Protection of 76%

Researchers at the University of Oxford published in Preprints with The Lancet on February 2, 2021, an analysis from the ongoing trials of the AZD1222 vaccine known as AstraZeneca COVID-19. They reveal that the vaccine efficacy is higher at longer prime-boost intervals.

And, that a single dose of the vaccine is 76% effective from 22- to up to 90-days post-vaccination.

In this non-peer-reviewed preprint, they report that the effect of dosing interval on efficacy is pronounced, with vaccine efficacy rising from 54.9% with an interval of fewer than six weeks to 82.4% when spaced 12 or more weeks apart. 

Professor Andrew Pollard, Chief Investigator of the Oxford Vaccine Trial, and co-author said in a press release, ‘These new data provide important verification of the interim data that was used by regulators to grant the vaccine emergency use authorization."

‘It also supports the policy recommendation made by the Joint Committee on Vaccination and Immunisation (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.’

The analysis authors also reported on the potential for the COVID-19 vaccine to reduce transmission of the SARS-CoV-2 virus, based on swabs obtained from volunteers in the UK arms of the trial with a 67% reduction after the first dose of the vaccine.