Note it is at least 90%. Case number is likely too low to give a tighter estimate with high enough confidence. That is, even if no one vaccinated is infected th

Note it is at least 90%. Case number is likely too low to give a tighter estimate with high enough confidence. That is, even if no one vaccinated is infected they still can't claim a much higher effectiveness with confidence as there are only 94 cases. So they are giving just a lower bound.