Unvaccinated Kids Behind Largest U.S. Measles Outbreak in Years: Study

Vaccination and quick public health response are limiting these outbreaks, experts say

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By Steven Reinberg
HealthDay Reporter

THURSDAY, Oct. 20 (HealthDay News) -- The largest U.S. outbreak of measles to occur in 15 years -- affecting 214 children so far -- is likely driven by travelers returning from abroad and by too many unvaccinated U.S. children, according to new research.

The finding could highlight the dangers of a trend among some U.S. parents to skip the measles-mumps-rubella (MMR) vaccine for their children, out of what many experts call misguided fears over its safety.

Dr. Andrew Pavlo, professor of pediatrics at the University of Utah and spokesman for the Infectious Diseases Society of America (IDSA), said, "The good news is that we are seeing introductions of measles that are being contained as small outbreaks."

Pavlo credits containment to high levels of vaccination and the rapid response by public health officials. However, if an outbreak occurred in a "really susceptible population the outcome could be very different," he said.

"What would happen in an area with a lot of vaccine refusers? Then you might see a much larger outbreak," he said.

Several measles-related studies were unveiled at the annual IDSA annual meeting, currently being held in Boston.

In the first report, U.S. Centers for Disease Control and Prevention (CDC) researchers chronicled the nation's ongoing outbreaks in 2011.

Most of those sickened were not vaccinated against the disease, CDC researchers said.

Before the vaccine became available in the 1960s, some three to four million people contracted measles every year. Of those, 48,000 were hospitalized, 1,000 were permanently disabled and about 500 died, the CDC said.

Unfortunately, "we have experienced an increased incidence of measles this year," said Huong McLean, lead researcher and CDC epidemiologist. "Typically we see 60 to 70 cases a year, this year we have 214 as of Oct. 14."

Among those people infected, 86 percent were unvaccinated or their vaccination status was unknown. Thirteen percent were under one year old -- too young for vaccination.

Throughout the United States, 68 of the patients have been hospitalized, 12 with pneumonia.

Most of these cases occurred among people who traveled overseas to Western Europe, Africa or Asia, where vaccination rates are lower, and the disease is an ongoing problem, the researchers note.

McLean said that the vaccination coverage in the United states remains relatively high, about 90 percent. "However, measles is very contagious and can spread quickly in communities where people aren't vaccinated," she said.

"The vaccine is very safe and effective in preventing the disease," McLean said. The MMR vaccine, which protects against measles, mumps and rubella (German measles), is designed to be given to infants 12 to 15 months old with a second shot given when the child is four to six, according to the CDC.

The Minnesota Department of Health released figures on a state outbreak, which started in March with an unvaccinated child, aged two and a half , who had traveled to Kenya. The child attended a drop-in Minnesota child care center. Overall, 21 people were infected and 14 hospitalized.

"Health care providers together with public health and community leaders must address growing vaccine hesitancy to ensure high immunization rates in all communities," Pam Gahr, a senior health department epidemiologist, said in an IDSA news release.

Not only is measles highly contagious, it's also expensive to contain its spread, according a third meeting presentation.

Dr. Karyn Leniek, deputy state epidemiologist for the Utah Department of Health, said an outbreak occurred when one unvaccinated high school student, who had been to Europe, brought measles back with him.

Although only nine people became infected, the cost of containing the outbreak was about $300,000. Costs included infection control in two area hospitals and intervention by local and state health departments. Costs also included physician and staff time, vaccines, immunoglobulin and blood tests, according to the study.