The USA has maintained an embargo on selling medicines to Cuba since 1964, as part of a general Cuban embargo since 1960. Health care in Cuba suffers badly due to a deficit in medicine, as well as other problems.
American governments have never willingly tolerated a Communist government close to its shores, and an embargo was imposed as part of the Cold War, because the American government claimed that Cuba represented a threat to its security.
The American government claimed in 1997 that Cuba does not spend enough money on medicine, and that the US is the largest donor of medicines to Cuba, neglecting to add that these are private donations not governmental ones.
The medical embargo is a war technique applied against civilians. It is motivated by American rage at Castro's insolence at maintaining power.
Despite the end of the Cold War, the Cuban embargo remains, while peculiarly, the American government is trying hard to engage another Communist government, the Chinese, in trade.
In 2001, the US government said it would not seek sanctions against poor countries ravaged by the AIDS epidemic, even if American patent laws relating to drug supplies are broken, so long as the country abides by World Trade Organization treaties.