The United States officially eliminated measles in 2000. Recent imported cases don't change that status but are creating small pockets in unvaccinated or undervaccinated people and threaten health security, researchers from the Centers for Disease Control and Prevention (CDC) reported today.
An expert panel charged with reviewing the elimination status of measles also looked at rubella and congenital rubella syndrome (CRS), documenting that the US has sustained elimination of those diseases, as well. The team detailed its findings today an early online edition of the Journal of the American Medical Association (JAMA) Pediatrics.
The CDC released the new data as part of actions that marked the 50th anniversary of the measles vaccine, which came with a tribute to Samuel L. Katz, MD, who played a key role in developing the vaccine. The virus had already been isolated, but Katz passaged it to create a weakened form that could be used in vaccine production.
Before the vaccine launched in 1963, measles affected nearly every American child and led to about 48,000 hospitalizations and 450 to 500 deaths. It also left thousands with seizures or permanent disabilities, including deafness, according to the agency.
A highly infectious disease
At a CDC media briefing today to unveil the expert panel's findings, Tom Frieden, MD, MPH, CDC director, called measles the most infectious of all infectious diseases, and he said the global arrival of the vaccine has saved 30 million children's lives. "That's astonishing," he said.
Katz, emeritus professor at Duke University, downplayed his accomplishment during the briefing. He praised the efforts of public health workers who deliver the vaccine to patients, especially those in resource-poor countries.
"Developing a vaccine can be fulfilling, but if it sits in a refrigerator, it's not helping anyone," Katz told reporters.
To determine if the United States has sustained elimination for the three conditions, the experts reviewed measles data from 2001 to 2011, and for rubella and CRS they looked at figures from 2004—the year elimination was documented—through 2011.
They found that measles incidence has remained below 1 per 1,000,000 population, with incidence for rubella and CRS even lower: 1 case per 10,000,000 and 1 case per 5,000,000, respectively.
Of measles cases, 88% were linked to importation, and of rubella infections, 54% were imported. The infections that weren't linked to importation didn't represent endemic transmission, and molecular analysis found no endemic genotypes, according to the report.
US surveillance systems are adequate for detecting endemic measles and blood tests and vaccine coverage data point to high levels of population immunity, according to the findings.
Though the US has maintained elimination of the diseases, imported cases continue, and health providers should suspect measles or rubella in patients with febrile rash illnesses, especially those who have a history of international travel or contact with an international visitor.
Recent cases, vaccine gaps
The CDC said today that 2013 so far has seen the second most US measles cases since the disease was eliminated. Frieden said the CDC has received reports of 175 cases, which included 20 hospitalizations but no deaths. He said 52 of the cases were imported, about half from Europe.
So far eight outbreaks have been reported, including the largest one since 1996, which sickened 58 members of an Orthodox Jewish community in Brooklyn, N.Y.
Frieden said that reducing measles cases, along with other infectious diseases, bolsters the health security of the United States and the world.
He said the measles vaccine is remarkably effective, "but it's an unfinished success story." First-dose coverage has to be early and high, and everyone needs a second dose, Frieden added.
There are still gaps in US measles vaccine coverage: In 15 states, 10% of children have not received their recommended doses, which can lead to localized outbreaks when cases are imported, Frieden said.
Support needed from physicians
In an editorial in the same issue of JAMA Pediatrics, Mark Grabowsky, MD, MPH, with a United Nations office based in New York City, wrote that growing parents' hesitancy is the greatest threat to the US vaccination program. He pointed to a recent large measles outbreak that was linked to a church that advocated the refusal of measles vaccination.
Grabowsky is with the Office of the Secretary General's Special Envoy for Financing the Health Millennium Development Goals and for Malaria.
"The single most important factor influencing decision making on childhood vaccination is the clear recommendation of a physician—clinicians must recognize their responsibility in supporting early vaccination." Grabowsky wrote.
He also wrote that ending measles and rubella in the Western Hemisphere could be a steppingstone to global eradication. "There is a consensus that the global eradication of measles will proceed if there is progress toward these regional goals."
Papania MJ, Wallace GS, Rota PA, et al. Elimination of endemic measles, rubella, and congenital rubella syndrome from the Western Hemisphere. JAMA Pediatr 2013 Dec 5 [Full text]
Grabowsky M. The beginning of the end of measles and rubella. (Editorial) JAMA Pediatr 2013 Dec 5 [Full text]
Dec 5 CDC press release