Trials of this or a similar monoclonal antibody pair in the US showed no reduction in deaths from Covid. For an expensive agent, one requiring injection and close monitoring for not inconsequential side effects, reduction in duration of hospital stay and duration of symptoms is a fairly marginal benefit. If it was a pill with a good side effect profile and of reasonable cost, that would be a different ball game.
The story for convalescent serum ( real antibodies harvested from people who had Covid) was similarly disappointing. Covid is a potentially fatal disease and the big prize is stopping people from dying.
OK there’s the use for Covid prevention in high risk populations such as nursing homes but hasn’t that been addressed by vaccination?