Those therapies were available then, but they were therapies for the infected, to prevent death. They didn't prevent infection. Lots of people on those therapies still died, because they didn't get to the hospital in time, or because they had other health conditions. And plenty of people who survived because of those drugs have lingering issues from COVID.Or in other words, kind of like the vaccines that came later. The monoclonal antibody and convalescent plasma treatments were available and effective, if the same FDA emergency authorization that was given later to the vaccines had been given to them. I think Regeneron is still under priority review and waiting for authorization, if I'm not mistaken. I guess Regeneron didn't donate enough money to the DNC.
Vaccines prevent that whole cycle. And in cases of 'breakthrough' infections, the effects are much much less. You know - an ounce of prevention and all that.