The delivery soon went into storage near São Paulo’s airport, Renato Strauss, a spokesman for the Health Ministry said. Two months later, the pills are still being held in a logistics center, according to Strauss.

The way the US medicine was configured may have sealed its fate before arrival. The hydroxychloroquine came in packet sizes of a hundred 400mg pills, according to the state health secretaries association, CONASS. They have to be broken down to smaller numbers before they can be distributed, Strauss said.

That work would be carried out at a Brazilian Army laboratory in Rio de Janeiro, and other official labs, he added. Strauss did not explain why that has yet to happen, although experts say this could be because the process is costly and time-consuming. Another spokeswoman for the health ministry said Anvisa — Brazil’s health regulatory body — gave permission for the process to begin last week.

A spokesman for the US Embassy in Brasilia declined to answer questions and referred further queries to the White House, which did not respond to emails.