Why not? Any mistake or design flaw in the trials reduces their value, it doesn't completely eliminate it. The mistake in the AZ trial is something I consider

Why not? Any mistake or design flaw in the trials reduces their value, it doesn't completely eliminate it. The mistake in the AZ trial is something I consider extremely embarassing and stupid (assuming the published information about it is correct). It's the kind of mistake nobody that actually works in a lab should make, and I really question the competency of the people involved here. But in the end this meant that a part of the study got a half-dose of the vaccine. That makes the interpretation a bit more difficult, but it does not invalidate the trial.