AstraZeneca manufacturing error clouds vaccine study results

LONDON (AP) — AstraZeneca and Oxford University acknowledged a manufacturing error that is raising questions about preliminary results of their COVID-19 vaccine.

A statement Wednesday describing the error came days after the company and the university described the shots as “highly effective” and made no mention of why some participants didn’t receive as much vaccine as expected.

In a surprise, the group of volunteers that got half a dose in the first of their two shots seemed to be better protected than the volunteers who got full doses.

The low-dose group was smaller and younger, however, which could have skewed the results, experts say.