The recent outbreaks of measles – one of the leading causes of deaths among young children – in the United States and Brazil suggest that immunization rates in some areas have dropped below levels needed to prevent the spread of imported into the Americas, according to the United Nations health agency.
The UN World Health Organization (WHO) and the Pan American Health Organization, based in Washington, D.C., reported in a press release issued Tuesday that there were 147 confirmed measles cases in four countries of the Americas this year as of February 8.
“Of that total, 121 cases were in the United States, linked primarily to an outbreak that began at Disneyland in California last December,” the PAHO/WHO press release said, adding that a single case in Mexico was also tied to that outbreak. Of the remaining cases, 21 were in Brazil and four were in Canada.
“Thanks to high levels of immunization, the Americas have been on track for more than a decade to be formally declared free of measles,” said Dr. Cuauhtemoc Ruiz, head of PAHO/WHO’s immunization programme. “Maintaining high levels of vaccine coverage is key to preventing and halting outbreaks and to protect our populations from the constant threat of imported cases.”
Measles had been considered eliminated from the Americas since 2002, due to the absence of endemic transmission of the disease as the result of the region's success in achieving high levels of immunization, through routine immunization programs and mass vaccination campaigns such as the annual Vaccination Week in the Americas, which PAHO/WHO have spearheaded for the past 13 years.
Now, measles elimination “is facing major challenges, with several ongoing importations of measles in some countries,” PAHO/WHO said in an epidemiological alert distributed Tuesday to member countries across the region.
The alert urges countries to strengthen measles surveillance activities and to “take appropriate measures to protect residents in the Americas against measles and rubella.”
“Countries in the Americas have reported cases imported from other regions every year during the past decade, but until recently, they did not lead to significant outbreaks,” said Dr. Ruiz. “The current outbreaks point to gaps in immunization that could allow measles and other vaccine-preventable diseases to take hold again and begin spreading in our hemisphere.”
Measles vaccine has been used for more than 50 years and has proven to be safe and effective. Globally, measles vaccine prevented an estimated 15.6 million deaths between 2000 and 2013.
PAHO/WHO recommends that children receive two doses of measles-containing vaccine before their fifth birthday and that levels of coverage with two doses be maintained at 95 per cent or more to prevent the spread of imported cases. Currently, an estimated 92 per cent of 1-year-olds in the Americas receive a first dose of measles vaccine.
PAHO, founded in 1902, is the oldest international public health organization in the world. It works with its member countries to improve the health and the quality of life of the people of the Americas. It also serves as the Regional Office for the Americas of the Geneva-based WHO.