1948    The World Health Organization is established by the United Nations.

1977    The last natural case of smallpox is discovered in Merca district, Somalia. The WHO and the CDC consider this date the anniversary of the eradication of smallpox, the most spectacular success of vaccination.

1980    The eradication of smallpox is endorsed by the World Health Organization.

1990    The General Assembly of the World Health Organization (WHO) eliminates homosexuality from the list of psychiatric diseases.