Table 1 Age-specific incidence (cases per thousand) of varicella and trends, Massachusetts, 1998–2003
Year | Parameter | Age group in years | ||||||
|---|---|---|---|---|---|---|---|---|
< 1 | 1–4 | 5–9 | 10–14 | 15–19 | 20+ | All ages, crude | ||
1998 | ||||||||
na | 144 | 762 | 1025 | 922 | 791 | 8241 | 11885 | |
Cases | 4 | 66 | 83 | 23 | 9 | 34 | 219 | |
Incidence | 15.2 | 82.6 | 76.4 | 18.6 | 30.2 | 2.2 | 16.5 | |
95% CI | 4.7–49.5 | 59.9–113.9 | 55.0–104.5 | 10.8–32.0 | 8.3–109.4 | 1.4–3.5 | 12.8–21.3 | |
1999 | ||||||||
na | 318 | 1603 | 1131 | 1094 | 898 | 8483 | 13527 | |
Cases | 4 | 46 | 41 | 11 | 3 | 17 | 122 | |
Incidence | 6.2 | 36.5 | 38.2 | 10.4 | 2.9 | 1.7 | 10.9 | |
95% CI | 1.2–31.6 | 21.1–63.0 | 24.8–59.0 | 4.8–22.5 | 0.6–13.4 | 0.9–3.4 | 7.8–15.1 | |
2000 | ||||||||
na | 139 | 671 | 790 | 918 | 693 | 7518 | 10729 | |
Cases | 1 | 7 | 9 | 9 | 3 | 3 | 32 | |
Incidence | 11.4 | 11.6 | 10.3 | 8.8 | 4.2 | 0.3 | 2.7 | |
95% CI | 1.4–53.7 | 4.7–25.6 | 4.8–20.6 | 4.0–18.1 | 0.8–19.8 | 0.1–1.23 | 1.8–4.3 | |
2002 | ||||||||
na | 161 | 600 | 780 | 831 | 705 | 7789 | 10866 | |
Cases | 1 | 4 | 5 | 3 | 1 | 6 | 20 | |
Incidence | 8.7 | 4.3 | 8.0 | 4.6 | 1.4 | 0.5 | 1.7 | |
95% CI | 1.1–44.6 | 1.2–13.9 | 3.0–20.0 | 1.3–15.4 | 0.2–9.7 | 0.2–1.1 | 1.0–2.8 | |
2003 | ||||||||
na | 155 | 613 | 827 | 914 | 726 | 8012 | 11247 | |
Cases | 0 | 7 | 15 | 6 | 2 | 10 | 40 | |
Incidence | 0.0 | 8.8 | 15.0 | 6.4 | 2.3 | 1.6 | 3.5 | |
95% CI | 3.6–20.2 | 7.8–27.0 | 2.7–14.4 | 0.6–9.2 | 0.8–3.1 | 2.3–5.2 | ||
1998–2003 | ||||||||
% change for period | -100% | -89% | -80% | -66% | -92% | -27% | -79% | |
p for trend test | n.a. | <0.0001 | <0.0001 | 0.02 | 0.15 | 0.16 | <0.0001 | |