Sham case-control or pilot studies before vaccine introduction can be useful in designing case-control VE studies.
Sham case-control studies, like real ones of vaccine effectiveness, are not useful in settings of extremely high vaccine coverage.
The findings from this sham case-control study will enable future rotavirus vaccine case-control studies in Kenya to be designed more efficiently.
Bias-indicator studies are a different type of sham case-control study than we performed, in that the sham is not the exposure (i.e. vaccine) but rather the outcome (i.e. type of gastroenteritis).
Our sham case-control study provided several important lessons that can be applied to a case-control study of rotavirus VE in the same setting after vaccine introduction, expected in 2014 [ 2].
The advantage of the bias-indicator approach is that it can be done contemporaneously with an actual case-control study of rotavirus AGE cases, which cannot be done for a sham case-control study like ours due to the co-administration of most EPI vaccines.
To inform the design and assess selection bias of a future case-control study of rotavirus vaccine effectiveness (VE) in western Kenya, we performed a sham case-control study evaluating VE of pentavalent vaccine (DTP-Hib-HepB) against rotavirus acute gastroenteritis (AGE).
Sham case-control studies of VE or pilot studies of existing vaccination patterns in communities should be considered prior to the start of other case-control studies of the target vaccine to assess the existence of selection bias and improve the study design and efficiency.
