Questions loom over Oxford vaccine's '90% efficacy' claim

Data show the vax is safe and protective but dosage remains an issue

The safety and efficacy of the Oxford COVID-19 vaccine has been confirmed in a published study but regulators will have to grapple with a dilemma over the optimum dosage.

The 62% efficacy for the planned vaccine dose, foreshadowed in the release of interim data two weeks ago, puts manufacturer AstraZeneca "in a difficult situation", says pandemic expert Professor Raina MacIntyre from the Kirby Institute, UNSW Sydney.

Data published in The Lancet on Tuesday show that among 1300 patients who