The purpose of this Request for Proposals is to identify a suitable contractor to develop analytical tools and mathematical models for infectious disease transmission and control studies. This involves developing the programme for implementing these methods in conjunction with data analysis. Implementing these methods that help vaccine trials design and analysis as well as developing optimal control methods once vaccines are made available. See detailed Terms of Reference and bidding instructions under “Documents” below.  Please note: it is NOT necessary to click on “Express Interest” on the top right-hand side of the screen. In order to inform WHO that you are interested in participating in this Request for Proposals, please follow the provisions of the RFP document below.