Applications of survival analysis methodologies in vaccine trials have some special issues and challenges. In many vaccine efficacy trials, validating a vaccine immunogenicity biomarker is an important task, yet sometimes it is often difficult or even infeasible to obtain immunogenicity measurements from the full cohort. The case-cohort and nested case-control designs have the potential to overcome this limitation due to their flexibility in subsampling. In this talk, we will first discuss the power and sample size considerations to evaluate the correlates of protection using survival methodologies, then we will discuss how to apply these case-control and case-cohort methods in vaccine studies. In addition, we will compare the performance of these two subsampling methods and a "hybrid" method, with that from the method utilizing the full cohort.