Americas becomes first region declared free of measles

The Americas became the first WHO region to be declared free of measles after going 14 years without an endemic case.

The announcement was made today during the annual Directing Council of the Pan American Health Organization (PAHO)/WHO in Washington, D.C.

The Americas also was the first region to eradicate smallpox in 1971, polio in 1994 and rubella and congenital rubella syndrome in 2015.

“This is truly a historic day,” PAHO Director Carissa F. Etienne, MBBS, MSc, said during a news conference. “It is proof of the remarkable success that can be achieved when countries work steadfastly to achieve common goals.”

Carissa F. Etienne

The declaration followed a 22-year effort to administer the measles-mumps-rubella vaccine in the Americas and a 6-year verification process by a committee of experts who were tasked with documenting that the disease had been eradicated.

Spread via coughing and sneezing, the highly contagious measles virus can cause pneumonia, blindness, brain swelling and death. It can be prevented with the MMR vaccine, which is about 93% effective at one dose and 97% effective at two doses, according to the CDC.

Primarily affecting children, measles was declared eliminated from the United States in 2000. Since then, as few as 37 people and as many as 668 per year have been sickened by the virus in the U.S. — most of them related to travel, the CDC says.

Measles caused nearly 2.6 million deaths annually before mass vaccination efforts were launched in 1980, including 101,800 deaths in the Americas between 1971 and 1979, according to PAHO. Decades later, only about 244,704 measles cases were reported worldwide in 2015, more than half of them in Africa.

Although the Americas has not had an endemic case of measles since a 2002 outbreak in Venezuela, the virus remains common in other countries and outbreaks still occur, such as the one linked to Disneyland theme parks in California starting in late 2014.

In fact, there were 5,077 imported cases of measles in the Americas between 2003 and 2014.

“Measles is one of the most infectious diseases that we know, and it’s just a plane ride away,” Mary M. Agócs, MD, MSc, senior adviser for the Measles and Rubella Initiative, a global partnership led by the American Red Cross, said during the news conference.

To be considered endemic, however, a disease must circulate in a region continuously for 12 months, according to Susan Reef, MD, rubella team leader in the Global Immunization Division at the CDC. This was not the case with the Disneyland outbreak in 2014-2015, in which a small population of unvaccinated people led to a cluster of infections, Reef said at the news conference.

“The outbreak was in a very specific population, and we were able to stop it quickly,” she said.

Countries in the Americas region launched their measles eradication effort in 1994 with a goal of ending transmission by 2000 using a three-step vaccination and surveillance strategy recommended by PAHO and WHO. The strategy included an initial push to vaccinate children aged 1 to 14 years, an effort to strengthen routine vaccination to reach a minimum of 95% of children annually, and follow-up campaigns every 4 years to get at least 95% of children aged 1 to 4 years a second dose of vaccine. – by Gerard Gallagher

Disclosures: Etienne, Agócs and Reef report no relevant financial disclosures.