How to use potential RSV preventive interventions wisely? A modelling study on seasonal-approaches of maternal vaccination and passive immunization

Li Y, Hodgson D, Wang X, Atkins KE, Feikin DR, Nair H

As soon as the temperature goes down by the end of summer and the beginning of fall, viruses are lurking around the corner. RSV is also such a virus, which has a clear seasonality in most countries. Maternal vaccination and passive immunization approaches for RSV are currently in development in clinical trials. However, both preventive measures will only offer an infant protection for approximately 3 to 5 months. Timing these defensive strategies right according to when RSV is planning to attack, could lead to an efficient strategy. Li and his colleagues tested this hypothesis with a computational model using efficacy data from the ResVax and nirsevimab trials. For 52 low- and middle-income countries (LMICs), effectiveness of various seasonal- and year-round programs was calculated and compared. One of the main findings was that in countries with clear RSV seasonality, an approach in which passive immunization started 3 months before RSV season onset was able to prevent 49.4% of RSV associated hospital admissions and 38.6% of the RSV-acute lower respiratory infections. Since this approach only averted 16% less of the hospital admissions than a year-round schedule, it was clearly more efficient. As soon as prophylactic medicines are available, it is important to use them in an efficient and feasible way, especially in LMICs, where the burden of RSV is highest and resources can be limited. This research is one of the first to explore different seasonal approaches.