You believe there was a high rate of adverse effects?Cheating or stupidity causing "mistakes"? You make the call on Astra Zeneca:
Meanwhile, one of their key claims is that giving half a dose of the vaccine on the first injection, followed by a standard dose on the second one, led to better outcomes—but neither of these trials had been designed to test this hypothesis. In fact, it’s since emerged that the half-dose/full-dose option started out as a mistake, and one that was only caught when some people in the study didn’t have the usual high rate of adverse effects.
My understanding is such a result would end the trial.
Unless by adverse effects you mean pain in the dosed arm, slight headache and fatigue for a few days.
All the vaccines appear to have those sides in some of the trials participants.