David Spiegelhalter has written many informative articles over the past few months. However, his recent piece (There’s no proof the Oxford vaccine causes blood clots. So why are people worried?, 15 March) suggests a misconception on his part.
He describes it as remarkable that 28% of volunteers receiving the dummy vaccine reported side effects. The “dummy vaccine” is, of course, not a dummy at all but a control vaccine consisting of a vaccine active against meningitis causing bacteria rather than the coronavirus. It would be more remarkable if an active vaccine did not cause some side effects.
I am a volunteer in the Oxford vaccine trial, and, having experienced local and systemic side effects on the first day after my first dose, thought to myself that I “must” have had the coronavirus vaccine. A quick internet search soon showed that the control vaccine has known side effects of a sore arm, feeling tired, headache etc, which is presumably why it was chosen rather than a saline “dummy”. So I was none the wiser as to which vaccine I had had, until more recently when I was unblinded and my original hunch was proved correct.
Dr David Coombs
Oxton, Wirral
