“So what do researchers know about the effectiveness of ivermectin, approved for human use but best known as a horse deworming medicine, in treating COVID-19? At the beginning of the pandemic, scientists around the globe began testing thousands of existing medications in test tubes to see if they could be repurposed to fight against the novel coronavirus. In very preliminary research, researchers found that ivermectin significantlyinhibited COVID-19 coronaviruses in cell cultures.
Encouraged by these petri dish findings, some desperate clinicians began administering ivermectin to their COVID-19 patients. The result was a number of hopeful observational studies by clinicians reporting that ivermectin appeared to be effective—in some cases, highly effective—in preventing COVID deaths. Observational studies are notoriously subject to researcher biases and confounders that can mislead clinicians into thinking an intervention works when actually a third factor is responsible.
Nevertheless, a prominent group of American physicians calling themselves the Front Line COVID-19 Critical Care Alliance (FLCCC) combined these preliminary observational and epidemiological studies into a November 13, 2020, preprint meta-analysis asserting that ivermectin “has highly potent real-world, anti-viral, and anti-inflammatory properties against SARS-CoV-2 and COVID-19.” Among other findings, the FLCCC pointed to reports that widespread distribution of ivermectin in Peru had correlated with steep declines in COVID-19 cases and mortality there. According to the group, cases and deaths began to rise dramatically in the same country after the government ceased distributing the drug.”
“research on ivermectin’s efficacy in treating COVID-19 has been ongoing. Has this subsequent research validated Kory’s claim that ivermectin is a miracle drug against COVID-19? It’s complicated, but the answer is largely no.
First: Those dramatic Peruvian results are highly confounded. The steep rise in COVID-19 cases and deaths in that country can most likely be blamed on the breakout of the highly infectious lambda variant rather than to a halt in ivermectin distribution. Meanwhile, the newly reported results of a highly anticipated randomized controlled study of ivermectin in next door Brazil finds that the medicine had “no effect whatsoever” on the disease.
A lot of the hope that ivermectin would be a COVID-19 silver bullet arose from the findings of various meta-analyses, including the one conducted by the FLCCC, that combined the results of various observational studies and small randomized controlled trials. One of the more prominent recent ones was posted as a preprint in May by a team of British public health researchers led by the Newcastle University statistician Andrew Bryant. But other scientists have faulted that study for significant methodological failures.
Also, though it’s not the preprint’s researchers fault, one of the most important studies bolstering their conclusion has been withdrawn because its results appear to be fraudulent. Once the data from that study are removed, the Bryant meta-analysis finds essentially no efficacy for treating COVID-19 with ivermectin.
On July 28, 2021, the authors of a more painstaking meta-analysis of ivermectin COVID-19 treatment studies, published by the Cochrane Library, concluded:
“Based on the current very low‐ to low-certainty evidence, we are uncertain about the efficacy and safety of ivermectin used to treat or prevent COVID‐19. The completed studies are small and few are considered high quality. Several studies are underway that may produce clearer answers in review updates. Overall, the reliable evidence available does not support the use of ivermectin for treatment or prevention of COVID‐19 outside of well‐designed randomized trials.”
The FLCCC folks are surely sincere, but the best evidence suggests that they are sincerely wrong. The bottom line is that while ivermectin might have some marginal efficacy, it is certainly not a “miracle drug” when it comes to treating COVID-19.”