It's likely that the stock has been halted for news that RVVTF will announce that it has filed an IND for it's proposed Phase 3 trial.
"Additionally, Revive is finalizing its IND with the U.S. FDA for the proposed Phase 3 confirmatory clinical trial to evaluate Bucillamine in the treatment of patients with mild-moderate COVID-19 due to the SARS-CoV-2 infection. The Company will file the IND later this month and expects final approval to proceed to the Phase 3 study shortly thereafter."