Effectiveness of maternal vaccines and long-acting monoclonal antibodies against respiratory syncytial virus hospitalisations in early life: a scoping review of dynamic modelling studies

BackgroundRespiratory syncytial virus (RSV) is a leading cause of respiratory illness and hospitalisation in infants and young children. New pharmaceutical interventions for preventing severe RSV in early life, namely a maternal vaccine and a long-acting monoclonal antibody, have recently been approved and are now available for use. Over the past decade, mathematical models of RSV transmission have been used to predict the impact of novel pharmaceutical interventions, in anticipation of future product licensure, and to model the potential impact of newly available interventions. However, these models have varied in structure, parameterisation, assumptions, and the immunisation schedules simulated. MethodsIn this scoping review, we surveyed published dynamic modelling studies that estimated the prospective population-level impact of either an RSV maternal vaccine or a long-acting monoclonal antibody in children <2 years, focussing on upper-middle- and high-income settings. We extracted data on the model structures, assumptions, and parameterisation, and synthesised the modelled estimates of future immunisation impact across studies. FindingsOf the 210 articles reviewed, a total of 7 studies met our criteria. Two studies modelled only a maternal vaccination strategy, one modelled a long-acting monoclonal strategy, and four modelled both. Estimates ranged from 5-21 and 11-32 annual RSV hospitalisations per 1,000 children averted for a maternal vaccine and a monoclonal antibody respectively in infants aged <3 months, corresponding to ranges of approximately 10-53% and 32-70% hospitalisations averted. Six of the studies explicitly captured natural maternally-derived immunity in infants following birth, but the magnitude and duration varied widely. InterpretationAll studies found that either a maternal vaccine and/or a long-acting monoclonal antibody could significantly reduce RSV hospitalisations in children younger than 12 months. We identified broad consistency in results across studies, and all studies captured declining impact in older children. Predicted impact was larger for a monoclonal antibody compared to a vaccine, due to higher assumed coverage and efficacy. Given assumptions around maternal immunity varied widely, improving both models and the evidence base for this process would be beneficial.