Varicella Vaccine: Are Two Doses Better Than One?

Varicella vaccine has been licensed in the U.S. since 1995, and in 2007, a two-dose schedule was adopted to decrease breakthrough disease. Other countries have been slower to incorporate varicella vaccine into their immunization schedules, and several countries only have a one-dose recommendation. In an industry-funded, randomized-controlled study, researchers randomized 5800 toddlers (age range, 12–22 months) from 10 European countries to receive two doses of measles-mumps-rubella-varicella (MMRV) vaccine, MMR followed by a single dose of monovalent varicella vaccine at dose two, or two doses of MMR (control) 6 weeks apart. The children were followed for 3 years for evidence of breakthrough varicella.

Single-dose vaccine efficacy against an…