TABLE 3

Incidence Rate of Breakthrough Varicella (First Episode Only) According to Year Since Vaccination (Rate per 1000 PYs): KPNC, 1996–2009

Years Since VaccinationFollow-up in PYAny LesionsMild (1–50 Lesions)Moderate (51–299 Lesions)Severe (>300 Lesions)
NRate95% CInRate95% CInRate95% CInRate95% CI
1653117426.622.9–31.015023.019.5–27.0203.11.9–4.840.60.2–1.7
2731115721.518.3–25.113618.615.7–22.0172.31.4–3.840.50.2–1.5
3704419127.123.5–31.316122.919.6–26.7273.82.6–5.730.40.1–1.4
4684119328.224.5–32.515322.419.1–26.2385.64.0–7.720.30.1–1.2
5667113420.116.9–23.810115.112.4–18.4324.83.3–6.910.10.0–1.0
6650511317.414.3–20.97912.19.7–15.2324.93.4–7.020.30.1–1.2
7642512012.615.6–22.48112.610.1–15.7385.94.2–8.210.20.0–1.0
862737918.710.1–15.8528.36.3–10.9274.32.9–6.300.00.0–0.8
961727612.39.8–15.5477.65.7–10.2284.53.1–6.610.20.0–1.1
106096559.06.9–11.8365.94.2–8.3183.01.8–4.810.20.0–1.1
116058538.76.6–11.5264.32.9–6.4233.82.5–5.840.70.2–1.8
125937488.16.0–10.8274.53.1–6.7183.01.9–4.930.50.1–1.6
135945203.42.1–5.381.30.6–2.8101.70.9–3.220.30.1–1.4
145886122.01.1–3.761.00.4–2.361.00.4–2.300.00.0–0.8
All years (0–14)89 695142515.915.1–16.7106311.911.2–12.63343.73.3–4.2280.30.2–0.5
  • Breakthrough episodes were defined as any reported varicella with onset of symptoms occurring >6 weeks after vaccination.