Oxford University’s coronavirus vaccine candidate provokes a better immune response when a two full-dose regime is administered rather than a full-dose followed by a half-dose booster, the university said. It citing data from early trials of its coronavirus vaccine.

The developers of the Oxford vaccine candidate, which has been licensed to pharmaceuticals company AstraZeneca, had earlier showed higher efficacy when a half dose is followed by a full dose, compared to a two full-dose regime. The latest data from the Oxford coronavirus vaccine Phase I and 2 clinical trials released on Thursday made no reference to the half-dose/full-dose regime, which Oxford has said had been “unplanned” but approved by regulators.

Once seen as the frontrunner in the development of a coronavirus vaccine, the British team has been overtaken by US drugmaker Pfizer, whose shots have been rolled out in Britain and the United States this month. The data which was published earlier showed Oxford coronavirus vaccine was 62 per cent effective for trial participants given two full doses. It showed a more robust 90 per cent for a smaller sub-group when it was given half in the beginning, then a full dose of the coronavirus vaccine.