Babies Born Early Antibody Response to Men B Vaccination: A Phase IV Multicentre Randomised Study to Evaluate the Primary and Booster Immune Responses in UK Preterm Infants Receiving Routine Immunisations and Incorporating a Three Dose Versus a Two Dose Schedule of 4CMenB (Bexsero®) for Primary Immunisation.

This will be an open label, phase IV study. After appropriate consent, 132 premature infants born at <35 weeks gestation (i.e. up to 34 weeks and 6 days), 50% <30 weeks gestation (i.e. up to 29 weeks and 6 days) will be randomised to 1 of 2 4CMen B schedules either at 2,4 and 12 months or 2,3,4 and 12 months. Babies will remain in the study for around 12 months, from recruitment to 13 months of age. All visits can be performed at the participant's home or in clinic, depending on the preference of the parents and study team.

Blood samples will be obtained at 5 months of age (post primary sample), 12 months (persistence sample) and 13 months (post booster sample). Reactogenicity and safety will be assessed by caregiver completion of a 7-day diary after each vaccine dose. Inpatients will be monitored for cardiorespiratory events for 72 hours after vaccination by healthcare staff and this information will be collected on the CRF. This will include details of oxygen saturations, heart rate, respiratory rate and details of any episodes of desaturation, bradycardia or apnoea. Particular emphasis will be placed on rates, timing and intensity of fever and other adverse reactions in the first 24 hours after vaccination, because this remains a cause of great concern amongst neonatologists.