More children around the world are getting the measles vaccine. As a result, fewer are dying. Some 20.3 million lives were saved between 2000 and 2015 thanks to the vaccine, according to a new report from UNICEF.

The number of measles deaths fell by 79 percent over the last 15 years. Even with that progress, close to 400 children die from the disease daily. The problem is concentrated in the Democratic Republic of the Congo, Ethiopia, India, Indonesia, Nigeria and Pakistan. These countries are responsible for more than 75 percent of measles deaths and half of all unvaccinated infants.

There is work to be done to eliminate measles deaths, but the solution is clear – vaccines.

“It is not acceptable that millions of children miss their vaccines every year. We have a safe and highly effective vaccine to stop the spread of measles and save lives,” said Jean-Marie Okwo-Bele, director of World Health Organization’s department of immunization, vaccines and biologicals, in a news release. “This year, the region of the Americas was declared free of measles – proof that elimination is possible. Now, we must stop measles in the rest of the world. It starts with vaccination.”

The Pan American Health Organization announced in September that measles is no longer endemic in North and South America. It is a major victory against the disease that killed nearly 2.6 million people in 1980. A concerted effort, led in large part by UNICEF, to increase vaccination coverage in developing countries is why fewer people die today.

Immunization gaps remain a major problem. Vaccination rates above 90 percent are needed to protect communities against measles. It keeps the people who are unvaccinated, such as newborns, safe from the disease. However, there are parts of the U.S. where vaccine rates are slipping below that threshold. A single outbreak that started at Disneyland in California infected at least 667 people from 27 U.S. states, last year.

Major measles outbreaks also occurred in Egypt, Ethiopia, Germany, Kyrgyzstan and Mongolia in 2015. Outbreaks in wealthier countries were caused by lagging vaccine rates. Flare-ups reported in Nigeria, Somalia and South Sudan were due to low vaccine coverage caused by conflict.

An estimated 20 million infants were not vaccinated against measles in 2015. The two-dose vaccine protects against the airborne disease. Improving coverage is important because it both protects people from the disease and improves overall vaccine coverage for other diseases like polio and pneumonia.

“Measles is a key indicator of the strength of a country’s immunization systems and, all too often, it ends up being the canary in the coal mine with outbreaks acting as the first warning of deeper problems,” said Seth Berkley, CEO of Gavi, the Vaccine Alliance, in a statement. “To address one of the world’s most deadly vaccine-preventable childhood killers we need strong commitments from countries and partners to boost routine immunization coverage and to strengthen surveillance systems.”

There is optimism that global elimination is possible. Closing the vaccination gaps and providing sufficient financial support are crucial, said Rebecca Martin, director of CDC’s Center for Global Health.

“These efforts will protect all children so that they can become the next generation of leaders,” she said in a statement.