Modeling the greenhouse gas emissions of an immunization program against respiratory syncytial virus in infants in the United Kingdom.

Objectives: The healthcare system accounts for 4 percent of United Kingdom (UK) greenhouse gas (GHG) emissions annually. In response to climate change, the National Health Service (NHS) is calling for less carbon-intensive care practices through prevention. Respiratory Syncytial Virus (RSV), a leading cause of infant hospitalization, currently has no widespread immunization program in the UK. This study estimates the impact on GHG emissions generated within the care pathway from an immunization against RSV in all infants in the UK with nirsevimab, a new monoclonal antibody used in prophylaxis.

Methods: A novel approach was applied, mapping care pathway emissions from immunization and avoiding RSV-related primary and secondary care burden. Avoided healthcare resources were estimated using a published health economic model for nirsevimab versus standard of care (SoC), which is characterized as receiving palivizumab or having no immunization intervention, assuming different universal immunization scenarios. NHS England GHG emission factors were applied to each health outcome to measure the GHG emissions associated with a nirsevimab versus SoC strategy.

Results: Compared with SoC, a universal immunization program using nirsevimab leads to avoided GHG emissions, amounting to ~22 kilotons of CO₂ equivalents per year, with immunizing all UK infants at birth leading to the greatest reduction. About 40 percent of avoided emissions were from reductions in inpatient hospitalizations.

Conclusions: This study shows how prevention can deliver benefits to people, NHS system capacity, and the environment. However, avoided patient care pathway emissions must be considered alongside drug lifecycle emissions, which are not included here.