Ivermectin’s popularity in Brazil was aided by its contrarian president, Jair Bolsonaro, who contracted Covid in July 2020 and refused to be vaccinated against the virus. Bolsonaro repeatedly promoted unproven Covid treatments such as ivermectin over policies like mask-wearing, social distancing or vaccination. Brazil spent millions of dollars producing and distributing “Covid kits” filled with cocktails of pills including ivermectin as part of its public health campaign, despite criticism from medical experts that there was no compelling evidence such kits were effective.

By June 2020, health officials and organizations across Latin America started pushing back against the use of ivermectin in the fight against Covid. That month, the Pan American Health Organization, an arm of the WHO, advised against using the drug for Covid. Brazil’s National Health Surveillance Agency, which regulates pharmaceuticals, issued a statement in July 2020 stating there was no conclusive evidence that ivermectin worked against coronavirus. Peru’s health ministry removed part of its recommendation for using ivermectin to treat Covid in October 2020, before cutting it altogether this year.

But much of the harm had been done, said Garcia. Ivermectin had given people a false sense of security against the virus, making it difficult for public health officials to later dispel unproven claims about the drug.