Mechanism of Action of Chloroquine/Hydroxychloroquine for Covid-19 Infection

Background: The recent serious outbreak of Covid-19 has required urgent medical treat-ments for numerous patients. No clinically active vaccines or antiviral agents are available for Covid-19. According to several studies, Chloroquine (CQ) and Hydroxychloroquine (HCQ) have shown potential as Covid-19 antivirals, especially when administered with Azithromycin (AZM). Objective: Here, we review the rationale behind this use. CQ/HCQ is effective against Covid-19 in--vitro and in-vivo laboratory studies. Therapy in Covid-19 infected patients with CQ/HCQ is supported by evidence of trials and field experiences from multiple sources. Methods: The relevant works are reviewed. The presence or absence of conflict of interest is weighed against the conclusions. Results: CQ/HCQ has been used with success in mild cases or medium severity cases. No randomized controlled trial has, however, been conducted to support the safety and efficacy of CQ/HCQ and AZM for Covid-19. Prophylaxis with CQ/HCQ is more controversial but generally not having side effects and supported by pre-clinical studies. The mechanism of action against Covid-19 is unclear. More research is needed to understand the mechanisms of actions CQ/HCQ has against Covid-19 infection, and this requires investigations with nanoscale imaging of viral infection of host cells. Conclusion: Most of the published works indicate CQ/HCQ is likely effective against Covid-19 in-fection, almost 100% in prophylaxis and mild to medium severity cases, and 60% in late infection cases. The percentage of positive works is larger if works conducted under a probable conflict of interest are excluded from the list.