There is a lot of conflicting information on the Internet about the effectiveness of chloroquine and hydroxychloroquine for the treatment of COVID-19. This information includes the successful use of these drugs against “coronaviruses” in the past. The confusion may arise from the fact, however, that COVID-19 is but one of many coronaviruses, which also include influenza and the common cold. The fact that a medication works against some members of this family does not guarantee that it will work against others.
The scientific basis for the use of chloroquine and hydroxychloroquine against influenza and related diseases consists of their purported ability to inhibit the cytokine storm, an immune reaction in which the patient’s immune system, rather than the virus, causes most of the damage. The cytokine storm was in fact blamed for the higher mortality rate among young patients (with stronger immune systems) than among older patients during the 1918 flu epidemic.
Conflicting results have been obtained with regard to these drugs’ effectiveness. The Henry Ford Health System reported, “Treatment with Hydroxychloroquine Cut Death Rate Significantly in COVID-19 Patients, Henry Ford Health System Study Shows.” The FDA warns, meanwhile, “FDA cautions against use of hydroxychloroquine or chloroquine for COVID-19 outside of the hospital setting or a clinical trial due to risk of heart rhythm problems.” Hydrochychloroquine, also known as Plaquenil, can cause retinal damage as well.
The key takeaway is therefore that the decision as to whether to use these drugs to treat COVID-19 is a patient-specific decision to be made by a medical doctor who is familiar with that patient’s condition and the risks of potential side effects. What works for one patient might not work for another, and what is harmless to one patient might cause serious side effects for another.