It is a long read but for those most interested in the benefit/risk evaluation skip to section 8. The very last statement 8.4 addresses the unknown risks that concern us all with the last paragraph most relevant.
https://www.fda.gov/media/144245/do...CDAiDEDTrPJPJvh4bBweWnv-0o8IzWudBpthk0#page46
https://www.fda.gov/media/144245/do...CDAiDEDTrPJPJvh4bBweWnv-0o8IzWudBpthk0#page46