Garasdil was approved by the FDA in 2006 and, as this press release shows [0], continued running studies into it as a condition of the approval. They conceded that full results could not be available before approval; “While the study period was not long enough for cervical cancer to develop, the prevention of these cervical precancerous lesions is believed highly likely to result in the prevention of those cancers.”
From what I can gather, the Phase III study participants continued to receive follow-up checks for at least a decade.
[0]https://web.archive.org/web/20091019080918/https://www.fda.g...
[0] https://www.fda.gov/news-events/press-announcements/fda-appr...
[1] https://www.wsj.com/articles/fast-track-drug-approval-design...
The completion date was changed multiple times since April 2020 and they clearly appended booster trials to the existing trials and pushed back the dates.
It truly is that simple.