Two-dose immunization of young children with the varicella vaccine, administered for chicken pox, has increased sharply since its recommended adoption just a few years ago, according to a new report.
The adoption of two doses of the vaccine for chicken pox has reached levels close to those of other vaccines since 2007, when the CDC's Advisory Committee on Immunization Practices began recommending a second dose for 4- to 6-year-olds, according to the report released Thursday by the Centers for Disease Control and Prevention
. The rate of coverage for two doses in children 7 and older has gone from a range of 3.6% to 8.9% in 2006 to between 79% and 92% by 2012, approaching the immunization rate for measles, mumps and rubella.
“We think that a large part of the quick increase for the second-dose coverage was due to providers just giving their kids when they came into the practice the second dose,” said Adriana Lopez, a CDC epidemiologist.
Healthcare providers have been a vital part of the success of two-dose vaccine coverage in the last few years since most states had yet to make it a requirement for children entering public school in the same way it had for vaccines against measles and diphtheria.
Only four states in 2007 required two-dose varicella vaccination, a number that increased to 36 by 2012. Adoption of a second-dose school-entry requirement by more states will help achieve the goals set by HHS' Healthy People 2020
initiative to reach a two-dose vaccination rate of 95%, Lopez said.
Preliminary studies have shown a second dose increases the effectiveness of the vaccine to around 98% compared with 94% when only one dose is administered, Lopez said.
Annual vaccinations of schoolchildren have been associated with the near elimination of an array of infectious diseases that once killed hundreds of Americans each year. Follow Steven Ross Johnson on Twitter: @MHSjohnson