This is outright wrong.

Monoclonal antibodies are, as you say, a treatment. They are not used to prevent infection in the first place. They lessen the severity of the disease but do essentially nothing to avoid its transmission.

You cannot end a pandemic without stopping the disease from spreading. For one, monoclonal antibodies do nothing to stop transmission. Second, their supply is constrained and availability is limited. Third, it cannot be used in all cases, most notably for folks whose symptoms have already become severe.