More work needed to verify AstraZeneca and Oxford University vaccine effectiveness

LONDON (Reuters) – AstraZeneca and Oxford University have more work to do to confirm whether their COVID-19 vaccine can be 90% effective, peer-reviewed data published in The Lancet showed on Tuesday, potentially slowing its eventual rollout in the fight against the pandemic.

Once seen as the frontrunner in the development of a vaccine against the coronavirus crisis, the British team was overtaken by U.S. drugmaker Pfizer, whose shots – with a success rate of around 95% – were administered to UK pensioners on Tuesday in a world-first hailed as V-Day.

Detailed results from the AstraZeneca/Oxford trials have been eagerly awaited after some scientists criticised a lack of information in their initial announcement last month.

However, the Lancet study gave few extra clues about why efficacy was 62% for trial participants given two full doses, but 90% for a smaller sub-group given a half, then a full dose.

“(This) will require further research as more data becomes available from the trial,” the study said.