Yes. The original trial required a total number of X people spanning the full range of ages and co-morbidities. But with the blunder, fewer than X people were assessed. Until the missing portion of the patients receives the nominal regimen of two full doses, the study, as it was designed, remains incomplete. The diminished number of patients will reduce the statistical power of the results, presumably to fall below what was deemed necessary and approved for the trial.

It's still possible that regulators will decide that 1) a sufficient number and range of ages and co-morbidies have in fact been assessed and that 2) the differential outcomes of the two groups is big enough to show the necessary level of efficacy and safety. But the 90% efficacy group clearly does NOT yet satisfy constraint #1, so until more 55+ year old subjects are added to the 90% efficacy part of the study, I suspect authorization will have to be based only on the 62% efficacy portion of the study.

I'm not an expert but the obvious solution is to give the Oxford/AstraZeneca vaccine to the 18-55 population and the mRNA vaccines to those 65+. The mRNA vaccines also have stringent and extreme freezing requirements that the Oxford one doesn't.