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Table 2 Examples of total sample sizes required for field studies of second-generation vaccine to demonstrate non-inferiority or superiority (reported in 1,000s; assuming intention-to-treat)

From: MALVAC 2012 scientific forum: accelerating development of second-generation malaria vaccines

Power (1-β) : 80%
Two-sided significance level (α) : 5%
Control vaccine efficacy : 50%
Follow-up time : 2 years
Incidence rate in those not vaccinated : 1/10 PYs
New vaccine efficacy (%) Superiority Non-inferiority margin
   5% 10%
50 --- 28.7 7.3
55 27.4 7.0 3.2
60 6.6 3.0 1.7
65 2.9 1.6 1.1
  1. Sample sizes are reported in 000’s and calculated using Z-test with continuity correction.