Overall, young children in the United States maintained high vaccination rates in 2012, officials at the U.S. Centers for Disease Control and Prevention (CDC) said Thursday.
But researchers also said there were 159 reported cases of measles between Jan. 1 and Aug. 24 this year — more than usual — and gaps in immunization appear to be to blame. The new data were published in the latest edition of the agency's Morbidity and Mortality Weekly Report.
In the first of the two papers, CDC researchers analyzed responses from the National Immunization Survey, which monitors vaccine coverage among children 19 to 35 months old. The federal government targets 90 percent childhood vaccination rates. Nationwide, Americans are hitting or exceeding that goal for measles, mumps and rubella; for polio; for hepatitis B and for varicella (the virus that causes chickenpox). Americans missed targets for diphtheria, tetanus and pertussis, and for Hib and PCV vaccines.
Alaska had the lowest rate for the combined vaccine series, at 59.5 percent, while Hawaii had the highest, at 80.2 percent.
The second report provided additional data on the 159 measles cases reported in 16 states, through August. Almost all of the cases were acquired outside the United States (where measles has been eliminated).
The statistics sound a warning against forgoing immunizations, the authors wrote. "The increase … serves as a reminder that imported measles can result in larger outbreaks, particularly if introduced into areas with pockets of unvaccinated persons," they wrote, mentioning an ongoing outbreak in Texas among members of a church group that is opposed to vaccination.