TABLE 2

Proportion of Varicella-Unprotected Children and Adolescents 5 to 19 Years of Age by Age Category and Survey Year, KPNC, 1995–2009

Survey Year5–9 Years10–14 Years15–19 Years
Unvac Hx (−) a Number Surveyed% b 95% CIUnvac Hx (−) a Number Surveyed% b 95% CIUnvac Hx (−) a Number Surveyed% b 95% CI
1995387112534.431.6–37.3157108514.512.3–16.9915587915.614.6–16.6
2000125112311.19.4–13.1133110812.010.1–14.2692598511.610.7–12.5
20034312633.42.5–4.610912708.67.0–10.4804713211.310.5–12.1
20062211811.91.2–2.85711365.03.8–6.559663509.48.7–10.1
2009710760.70.3–1.31410821.30.7–2.245960497.66.9–8.3
  • a Unvac Hx (−) (unvaccinated history-negative individuals): Individuals with no record of varicella vaccination and reported to have no history of varicella disease were considered susceptible to varicella. Varicella disease history was based on parental or self-report of varicella disease before the survey year. Vaccination status was obtained from the KPNC immunization database.

  • b %: The proportion of individuals susceptible to VZV infection (first column) among individuals surveyed in this age category (second column).