The Americas have become the first region in the world to successfully eliminate rubella, according to a World Health Organization (WHO) announcement last week. This easily transmitted virus is particularly dangerous for pregnant women as it can cause serious birth defects.

Public health officials credit the widespread vaccine program and targeted campaigns to vaccinate adolescents and adults in Latin America and the Caribbean with eliminating this disease, but recent distrust of vaccines and outbreaks of the measles have some worried about maintaining this progress.

Though sometimes called German measles, rubella is caused by a different virus than the measles and is usually milder. The virus causes a rash in children on the face and a low-grade fever, both of which last for two or three days. Older children and adults may also have swollen glands and aches in their joints. Some people who are infected, however, will have no symptoms.

Rubella is most dangerous in pregnant women as it can cause birth defects, including deafness, cataracts, heart defects, mental retardation, and liver and spleen damage. It can also cause miscarriage and stillbirth. It is estimated that if a woman is infected early in her pregnancy there is at least a 20 percent chance of damage to the fetus.

Babies exposed to rubella in utero are said to have congenital rubella syndrome (CRS) and may exhibit symptoms such as cloudy corneas or white appearance to pupils, excessive sleepiness, low birth weight, small head size, skin rash at birth, and seizures. These children may also have developmental delays and intellectual disabilities.

There was a global rubella pandemic between 1962 and 1965. It was estimated that there were 12.5 million rubella cases in the United States alone during that time, resulting in 2,000 cases of encephalitis, 11,250 therapeutic or spontaneous abortions, 2,100 neonatal deaths, and 20,000 infants born with CRS.

The rubella vaccine became available a few years later, in 1969, and widespread use of the vaccine led to a tremendous decline in the disease across the country.

Vaccinations for rubella today are given as part of the MMR (measles, mumps, and rubella), which is recommended for all children at 12-to-15 months, with a booster shot at age 4. The United States, thanks to widespread use of the vaccine, declared rubella eliminated in 2004. There were four cases of CRS reported between 2005 and 2011, with most of these cases involving mothers born outside of the United States who had not been vaccinated.

While the United States saw success a decade ago, other countries in the Americas struggled to contain the disease.

Until taking direct action in the late 1990s, Latin America and the Caribbean saw 16,000-20,000 cases of CRS each year and 176,000 cases of rubella in 1997 alone. WHO explains that beginning in 1998, the English-speaking Caribbean countries began rubella vaccination campaigns for adolescents and adults. That resulted in about 250 million vaccinations in 32 countries.

The success of these campaigns has meant that there have been no endemic outbreaks in the region for five years—the definition of having eliminated a disease. This does not mean that there have been no cases of rubella in the Americas in five years, but that all cases have been traced to carriers from other countries.

WHO officials warn that the Americas have to stay vigilant about prevention.

“The elimination of rubella from the Americas is a historic achievement that reflects the collective will of our region’s countries to work together to achieve ambitious public health milestones,” Carissa Etienne, director of the Pan American Health Organization, said in a statement. “Ours was the first region to eradicate smallpox, the first to eliminate polio, and now the first to eliminate rubella [and CRS]. All four achievements prove the value of immunization and how important it is to make vaccines available even to the remotest corners of our hemisphere.”

The next step, according to the WHO, is to go after measles globally, which is much more contagious and has greater health consequences in children and adults.

The United States has seen one of the largest measles epidemics in years with 166 cases reported in 19 states between January and April. Many health officials believe this outbreak is partly caused by misinformation about vaccines that has led some parents to choose not to vaccinate their children, as Rewire has reported. In fact, the MMR—the shot that covers both measles and rubella—has been the focus of this controversy as some parents believe it causes autism.

Numerous studies, however, has shown this is not true.

“Now it’s time to roll up our sleeves and finish the job of eliminating measles as well,” Etienne said in a statement.