Table 3.

Estimated Seizure Rates Before (During 2000–2006) and After (During 2008–2013) Rotavirus Vaccine Introduction, by Season and Age Group

Age Group, Season,a Time Analyzed	Seizure Rate, Cases/100 000 (95% CI)		Rate Ratio (95% CI)		P
0–59 mo
Rotavirus season
Before introduction	386.29 (384.39–388.20)		1
After introduction	366.13 (364.17–368.11)		0.95 (0.94–0.95)		<.0001
Nonrotavirus season
Before introduction	346.41	(344.61, 348.22)	1
After introduction	334.75	(332.87, 336.64)	0.97	(0.96, 0.97)	<.0001
6–11 mo
Rotavirus season
Before introduction	448.55	(442.17, 455.03)	1
After introduction	453.52	(446.62, 460.54)	1.01	(0.99, 1.03)	.3
Nonrotavirus season
Before introduction	401.48	(395.45, 407.61)	1
After introduction	404.12	(397.60, 410.74)	1.01	(0.98, 1.03)	.56
12–17 mo
Rotavirus season
Before introduction	552.60	(545.46, 559.83)	1
After introduction	493.24	(486.05, 500.53)	0.89	(0.88, 0.91)	<.0001
Nonrotavirus season
Before introduction	454.44	(447.97, 461.00)	1
After introduction	429.88	(423.18, 436.69)	0.95	(0.93, 0.97)	<.0001
18–23 mo
Rotavirus season
Before introduction	434.67	(428.35, 441.09)	1
After introduction	401.00	(394.53, 407.58)	0.92	(0.90, 0.94)	<.0001
Nonrotavirus season
Before introduction	349.11	(343.45, 354.87)	1
After introduction	328.81	(322.95, 334.77)	0.94	(0.92, 0.97)	<.0001

Data are from the State Inpatient Databases of the Healthcare Cost and Utilization Project [13] and include the following states: Arizona, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Iowa, Illinois, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Missouri, North Carolina, New Jersey, New York, Oregon, South Carolina, Tennessee, Texas, Utah, Washington, Wisconsin, and West Virginia.

Abbreviation: CI, confidence interval.

^aThe peak season of rotavirus infection lasts from January to June.