Table 4. Reported Number of Varicella Cases and Incidence Rates (per 1,000 population) by Age Group in Sentinel Surveillance Sites in Antelope Valley, Calif., and West Philadelphia, Pa., 1995 and 2005.

	No. of cases		Rate per 1,000		2005 vs. 1995
Antelope Valley	1995	2005	1995	2005	% Change
Age group (yrs.)
<1	134	16	19.7	3.2	-83.9
1–4	1,127	50	48.8	2.5	-94.9
5–9	1,228	122	54.9	4.6	-91.6
10–14	235	128	10.8	3.9	-63.9
15–19	65	15	3.1	0.5	-85.5
≥ 20	145	31	0.8	0.1	-82.0
Total	2,934	362	10.3	1.1	-89.8
	No. of cases		Rate per 1,000		2005 vs. 1995
West Philadelphia	1995	2005	1995	2005	% Change
Age group (yrs.)
<1	38	7	8.8	1.9	-78.7
1–4	358	30	20.8	2.0	-90.3
5–9	534	29	27.3	1.6	-94.2
10–14	162	13	8.9	0.7	-92.8
15–19	39	6	1.9	0.2	-87.8
≥ 20	60	23	0.3	0.1	-57.3
Total	1,197	108	4.1	0.4	-90.4

Source: Guris D et al. Changing varicella epidemiology in active surveillance sites, United States, 1995–2005; Journal of Infectious Disease. 2008: 197 (Suppl 2) S71–5