You all can argue the merits of the vaccine all you want.
The fact is, it is now a requirement of employment. The requirement appears to be in conjunction with formal approval by the CDC in Sept, thus removing many people's objection to an experimental vaccine. However, ALPA appears to be an ostrich with head firmly planted in the sand on the legality and application of the LOA.
Be prepared to not be a pilot for UAL if you choose to not get the vaccine--the medical, or religious exception will be a high threshold to meet.