MMGH supported the WHO Initiative for Vaccine Research (IVR) in developing a variety of forecast scenarios for the demand of a group B streptococcal (GBS) vaccine administered through maternal immunisation. The forecast was validated by an Expert Advisory Group. Based on the potential vaccine profiles, MMGH assessed the financial viability of the vaccine for a prospective developer. The output of the work will inform the WHO Public Health Value Proposition and contribute to advocacy efforts aimed at supporting the creation of a healthy market for the vaccine.