I think that the idea that the "planned interim analysis" included an efficacy analysis gains a lot of support from the fact that it was announced in an October PR that announced the pre-IND meeting request.
That would have been well before any talk between IPIX and the FDA regarding any dosage considerations so there would have been no need to plan a specific safety analysis at that time for that purpose.
The planned analysis may not happen given the size and status of the trial. Or it could happen without public notice. I would have expected the DMC to take note of the plan when hired.