North and South America have become the first regions of the world to eradicate rubella, or German measles, after no home-grown cases in five years.
The virus - spread by sneezes or coughs - can lead to serious birth defects if contracted by pregnant women.
Up to 20,000 children were born with rubella in the Americas every year until mass vaccinations started.
But the last endemic cases registered in the region were in Argentina and Brazil in 2009.
The fact no new cases have been declared in five consecutive years, apart from those imported into the region, allowed global health chiefs to declare the Americas free of the virus.
Eradication was "an historic achievement", said Carissa Etienne, director of the Pan-American Health Organization, which is part of the World Health Organization.
"The fight against rubella has taken more than 15 years," she said. "But it has paid off with what I believe will be one of the most important pan-American public health achievements of the 21st Century."
What is rubella?
Rubella is also called German measles. It is caused by a virus and spreads when an infected person coughs or sneezes.
Usually rubella causes a rash, a slight fever, aching joints, headaches, runny nose and red eyes. The rash starts on the face and spreads from head to toe.
Sometimes the lymph nodes behind the ears and on the neck can swell painfully.
Rubella can be dangerous for pregnant women in the first three months of pregnancy.
It can lead to congenital rubella syndrome (CRS) in children, and cause autism, blindness, deafness and heart defects.
During the last major rubella outbreak in the region, between 1964 and 1965, close to 20,000 children were born with CRS in the United States. The country managed to wipe out the virus by 2004.
However, about 120,000 new cases of rubella emerge every year, particularly in south-east Asia and Africa.
An outbreak of measles - a highly contagious virus - infected 150 people in the US alone at the turn of the year, after spreading from the Disneyland resort in California.
Doctors blamed the outbreak on parents refusing to give their children the MMR vaccine - the same one that prevents rubella - due to fears about potential side-effects.
Before that outbreak, the US had been free of measles for 15 years.