. Author manuscript; available in PMC: 2010 Jan 26.

Published in final edited form as: J Infect Dis. 2009 Aug 1;200(3):321–328. doi: 10.1086/603560

Table 3.

Number of Subjects Required to Test the Existence of an Increased Level of Risk Relative to Background Rate, with Type 1 Error α = 5% and Power of 90%

Background SAE rate in the general population	SAE rate in vaccinated populations
Background SAE rate in the general population	×1.5	×2	×5	×10	×100
1 of 10,000	453,000	141,000	16,000	5500	500
1 of 100,000	4,530,000	1,238,000	160,000	53,500	2500
1 of 1,000,000	43,128,500	12,951,500	1,599,000	532,500	23,500
1 of 10,000,000	438,525,500	123,781,500	15,987,500	5,322,500	230,500
1 of 100,000,000	4,312,838,000	1,237,814,000	159,872,000	53,223,500	2,303,000

NOTE. See Appendix A for technical details. SAE, serious adverse event.