How chloroquine came to the center of Brazil’s pandemic response

On Tuesday, the Senate inquiry into the Brazilian government’s pandemic response will grill Mayra Pinheiro, the Health Ministry’s education and labor management secretary. A largely anonymous figure in the government, Ms. Pinheiro is best known by her ignominious nickname: “Captain Chloroquine.” The Brazilian government sought to manufacture and distribute the antimalarial drug as an official strategy to combat the coronavirus, and Ms. Pinheiro was among the leading minds behind this decision.

First touted as a potential coronavirus treatment early in 2020, chloroquine’s efficacy against Covid-19 has long been dismissed by the scientific community in most of the world — with the exception of Brazil, where far-right President Jair Bolsonaro still endorses the medicine as a possible miracle cure.

Chloroquine became a part of Brazil’s official pandemic policy in March 2020, when the Health Ministry drafted protocols recommending its use for severe coronavirus cases. In May, the government extended this guidance to mild and moderate infections.

Traditionally used to treat malaria, rheumatoid arthritis, and lupus, the story of chloroquine being used to fight Covid-19 began with French microbiologist Didier Raoult,...