Figure 4.

Power of alternative designs for comparative studies with respect to (a) an odds ratio of 0.67 (true relative risk of 0.7) and (b) an odds ratio 0.84 (true relative risk of 0.85). The black lines represents home visits with subsequent virological confirmation for all families on the specified days, the medium grey lines represent self-report of ILI or ARI without virological confirmation and the light gray lines represent home visit with subsequent virological confirmation triggered by reports of ARI or ILI by a household contact.