Late last month, Oxford and AstraZeneca said its vaccine candidate for Covid-19, AZD1222, could have an efficacy up to 90 per cent — when administered in a half-dose followed by a full dose a month later. What they did not disclose initially was that these findings were the result of a mistake. The nearly 3,000 participants in the UK on whom this result was based were never supposed to be given a lower dose in the first place.
The revelation added to doubts on how vaccine clinical trials during the pandemic have been handled. Here’s a look at why it matters, and what needs to be done now:
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