I had that misunderstanding at first, too. But as far as I understand it now, this was a trial with ~30,000 people, and they report the first n number of people to get covid. In this case, n=95, and 90 of those 95 were in the control (placebo) group. The assumption is that with an ineffective vaccine, the control/experimental covid ratio would be 50/50, so the heavy skew to the control group is good and significant news. So this is not a sample where just 90 people were given the vaccine, which would be less reliable.
