Table 6.

Absolute Reduction per 10,000 Child-Years of Acute Gastroenteritis Hospitalizations Prevented by the Rotavirus Vaccination Program in Commercially Insured US Infants and Children, 2007–2010^a

Calendar Year by Effectiveness	Observed No. of Acute Gastroenteritis Hospitalizations in Minuend	No. of Child-Years in Minuend	Rate Per 10,000 Child-Years (IR1)	Observed No. of AGE Hospitalizations in Subtrahend	No. of Child-Years in Subtrahend	Rate Per 10,000 Child-Years (IR0)	Observed IRD Per 10,000 Child-Yearsb	95% CI for IRD
Direct effectiveness: vaccinated versus unvaccinated in same year
2007	142	28,209	50.3	271	37,696	71.9	−21.6	−33.5, −9.6
2008	413	85,259	48.4	317	39,319	80.6	−32.2	−42.2, −22.2
2009	512	131,096	39.1	300	32,165	93.3	−54.2	−65.3, −43.1
2010	398	118,520	33.6	109	18,932	57.6	−24.0	−35.3, −12.7
Indirect effectiveness: unvaccinated versus prevaccine periodc
2007	271	37,696	71.9	2,021	216,117	93.5	−21.6	−31.1, −12.1
2008	317	39,319	80.6	2,021	216,117	93.5	−12.9	−22.7, −3.1
2009	300	32,165	93.3	2,021	216,117	93.5	−0.3	−11.6, 11.1
2010	109	18,932	57.6	2,021	216,117	93.5	−35.9	−47.5, −24.4
Total effectiveness: vaccinated versus prevaccine periodc
2007	142	28,209	50.3	2,021	216,117	93.5	−43.2	−52.4, −34.0
2008	413	85,259	48.4	2,021	216,117	93.5	−45.1	−51.3, −38.9
2009	512	131,096	39.1	2,021	216,117	93.5	−54.5	−59.8, −49.2
2010	398	118,520	33.6	2,021	216,117	93.5	−59.9	−65.2, −54.7
Overall effectiveness: total in vaccine year versus prevaccine periodc
2007	413	65,905	62.7	2,021	216,117	93.5	−30.9	−38.1, −23.6
2008	730	124,578	58.6	2,021	216,117	93.5	−34.9	−40.8, −29.0
2009	812	163,261	49.7	2,021	216,117	93.5	−43.8	−49.1, −38.5
2010	507	137,452	37.0	2,021	216,117	93.5	−56.6	−61.8, −51.4

Abbreviations: AGE, acute gastroenteritis; CI, confidence interval; IRD, incidence rate difference.

^a Assumes 100% sensitivity and specificity of the AGE diagnostic codes.

^b Calculated using the formula, IR₁ − IR₀.

^c Prevaccine period, 2001–2005.