AstraZeneca manufacturing error clouds vaccine study results

In a surprise, the group of volunteers that got a lower dose seemed to be much better protected than the volunteers who got two full doses. In the low-dose group, AstraZeneca said, the vaccine appeared to be 90 per cent effective. In the group that got two full doses, the vaccine appeared to be 62 per cent effective. In the group that got two full doses, the vaccine appeared to be 62 per cent effective.