In June, the federal Advisory Committee on Immunization Practices recommended that children ages4 to6 get a second shot. The vaccine was introduced in 1995 with a recommendation that a child get a shot by age1. The Antelope Valley was chosen for the study because of its relative isolation. The other area being studied was Philadelphia. “It’s an isolated part of L.A. County. There was no way we could have counted all the cases in the county,” said Dr. Laurene Mascola, chief of the Acute Communicable Disease Control branch of the county Department of Health Services. “In the Antelope Valley, there is a separate-enough population. If you lived in the Antelope Valley, it was more likely you stayed there and got the disease and saw a local pediatrician.” The study looked at the number of “breakthrough” cases of varicella that occurred in children who had been vaccinated against the disease. The study found that the annual rate of breakthrough varicella significantly increased with time after vaccination. LANCASTER – In a study that focused on children in the Antelope Valley, researchers found that protection from a chickenpox vaccine tends to wane over time, reinforcing a recommendation that children get a second dose. The Antelope Valley was one of two areas where officials were monitoring the success of the vaccine against varicella, the medical name for chickenpox, as part of a 10-year study. “The study found that protection from varicella vaccine tends to wane over time. The waning immunity may result in increased susceptibility to varicella later in life, when risks of severe complications are greater,” said Curtis Allen, spokesman for the U.S. Centers for Disease Control and Prevention. The study, published last week in the New England Journal of Medicine, concluded that a second dose of the vaccine could improve protection against chickenpox, the itchy and sometimes-dangerous childhood scourge. Children ages 8 to 12 who had been vaccinated at least five years earlier were significantly more likely to have moderate or severe chickenpox than were those who had been vaccinated less than five years earlier. “It seems, over time, your protection against the disease decreases,” Mascola said. The vaccine is not 100percent effective, Allen said. About 15percent to 20percent of children can develop chickenpox although they have been vaccinated. “Typically, breakthrough cases are less severe,” Allen said, than chickenpox in children never vaccinated. More than 11,000 cases of chickenpox were reported among children and adults in the study from 1995 to 2004, and 1,080 of these were breakthrough cases, the study found. “The bottom line was you were very much (more) likely to get breakthrough disease the longer you were (past) getting the first vaccine,” Mascola said. Mascola said children can get the first and recommended second shot with a new multiple vaccine that provides protection against measles, mumps, rubella and chickenpox – the MMRV. Chickenpox usually strikes preschoolers and children in elementary school. Most often, the effects are no more serious than fever, itchy pustules on the skin and about two weeks of missed school. Chickenpox is rarely fatal but can have serious complications when a lesion becomes infected with bacteria, especially streptococcus. In April 1994, four children with chickenpox in Orange and Los Angeles counties died within weeks of one another after being infected. [email protected] (661) 267-5744 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set!