Table 4. Proportion of sentinel surveillance systems^a recording a change in the number of children aged under 5 years with invasive pneumococcal disease (IPD) from 1998–1999 to 2006^b that agreed^c with the change recorded in their surveillance area,^d United States of America.

IPD cases seen by each sentinel systema	IPD caused by any serotype			IPD caused by serotypes in PCV7e			IPD caused by serotypes not in PCV7e
	Sentinel systems in agreement/all sentinel systemsf (No./no.)	Sentinel systems in agreement (%)		Sentinel systems in agreement/all sentinel systemsf (No./no.)	Sentinel systems in agreement (%)		Sentinel systems in agreement/all sentinel systemsf (No./no.)	Sentinel systems in agreement (%)
Annual average of cases in 1998–1999g
0 to 10	57/181	31		164/171	96		41/114	36
11 to 20	230/330	70		301/330	91		210/323	65
21 to 30	280/328	85		328/328	100		204/328	62
31 to 40	218/223	98		223/223	100		205/223	92
41 to 50	42/43	98		43/43	100		41/43	95
51 to 60	46/46	100		46/46	100		46/46	100
61 to 70	25/25	100		25/25	100		25/25	100
71 or more	3/3	100		3/3	100		3/3	100
All	901/1179	76		1133/1169	97		775/1105	70
Proportion (%) of surveillance area's cases in 1998–1999g
0–10	17/103	17		92/93	99		12/50	24
11–20	65/124	52		109/124	88		56/111	50
21–30	114/178	64		158/178	89		108/172	63
31–40	188/231	81		231/231	100		156/229	68
41–50	216/236	92		236/236	100		165/236	70
51–60	148/153	97		153/153	100		125/153	82
61–70	101/102	99		102/102	100		101/102	99
71–80	42/42	100		42/42	100		42/42	100
81–90	10/10	100		10/10	100		10/10	100
91–100	NA	NA		NA	NA		NA	NA
All	901/1179	76		1133/1169	97		775/1105	70

NA, not applicable; PCV7, seven-valent pneumococcal conjugate vaccine.

^a Each sentinel system comprised either a single hospital with at least one hospitalized IPD case in either 1998 or 1999 or a group of hospitals in which each hospital had at least five cases during 1998 and 1999 combined.

^b PCV7 was introduced in the United States in 2000.

^c The change in the number of hospitalized cases of IPD in children aged under 5 years from the average in 1998 and 1999 to 2006 seen by a sentinel surveillance system was judged to be in agreement with the change observed in the corresponding surveillance area when the magnitude of the change in number recorded by the surveillance system fell within the 95% confidence interval of the magnitude of the change in the incidence of hospitalized IPD cases for the corresponding surveillance area.

^d Areas covered by the Active Bacterial Core surveillance system.

^e PCV7 includes Streptococcus pneumoniae serotypes 4, 6B, 9V, 14, 18C, 19F and 23F.

^f The denominators vary across the columns because some sentinel hospitals either did not have any IPD cases caused by serotypes in PCV7 or did not have any cases caused by serotypes not in PCV7 in 1998 or 1999.

^g P < 0.0001 for trend (exact Cochran-Armitage test) for IPD due to all serotypes, serotypes in PCV7 and serotypes not in PCV7.