See Humira [1]. Costs more than 5x more in the US than the UK. I’m not speculating on what a potential anti covid drug will cost; I’m talking about existing mAb therapies. And I didn’t think it a controversial point that drug companies charge as much as they can while their therapies are still protected by patents and, in the case of antibodies, manufacturing expertise.

1: https://en.m.wikipedia.org/wiki/Adalimumab