M. Elizabeth Halloran, Emory University
Using Validation Sets for Exposure to Infection and for Outcomes
in Vaccine Field StudiesMethods for adjusting for bias in
estimates due to mismeasured or missing covariates and outcomes have
been developed in many types of health studies. These methods can be
used for the efficient design and analysis of vaccine studies as well.
Data on exposure to infection can influence estimates of vaccine
efficacy, but good data on exposure is difficult to
obtain. Non-specific case definitions can lead to very attenuated
efficacy estimates, but confirmation by culture of the infectious
agent is expensive and difficult. Use of small validation sets can
correct the bias of the estimate from the large main study while
maintaining efficiency. Using semiparametric methods, we illustrate
the use of validation sets for exposure to infection on the example of
an HIV vaccine trial. We present initial exploration of the use of
validation sets for outcomes in influenza vaccine studies.