Lastly, other strategies are being clinically evaluated to treat COVID-19 patients as they may produce direct or indirect antiviral effects. These include the use of convalescent plasma (hyperimmune plasma) from fully recovered individuals [302], immunoglobulins, INFs (such as INF β-1a, INF β-1b, pegylated INF γ-1a and others) [303,304], RNA virus-based gene vector (such as DeltaRex-G) (NCT04378244; n = 18), and mesenchymal stem cells [305]. Furthermore, several anti-inflammatory/immune-modulatory drugs, antithrombotic drugs, and vitamins (vitamins C and D) are also being tested to prevent and/or treat severe COVID-19 cases that may arise because of excessive inflammation and thrombotic complications. Most frequently tested anti-inflammatory/immunomodulatory agents are listed in Table 2. Antithrombotic agents that are most frequently being tested in clinical trials for COVID-19 patients are also listed in Table 3.