Potential Impact of Nirsevimab on RSV Transmission and Medically Attended Lower Respiratory Tract Illness Caused by RSV: A Disease Transmission Model

Nicolas Voirin; Victor Virlogeux; Clarisse Demont; Alexia Kieffer

doi:10.1007/s40121-021-00566-9

Potential Impact of Nirsevimab on RSV Transmission and Medically Attended Lower Respiratory Tract Illness Caused by RSV: A Disease Transmission Model

Infect Dis Ther. 2022 Feb;11(1):277-292. doi: 10.1007/s40121-021-00566-9. Epub 2021 Nov 23.

Authors

Nicolas Voirin¹, Victor Virlogeux^{1

2}, Clarisse Demont³, Alexia Kieffer⁴

Affiliations

¹ Epidemiology and Modelling in Infectious Diseases (EPIMOD), Lent, France.
² Hospices Civils de Lyon, Lyon, France.
³ Vaccine and Epidemiology Modelling, Sanofi Pasteur, Lyon, France.
⁴ Health Economics and Value Assessment, Sanofi Pasteur, Siège Mondial, 14 Espace Henry Vallée, 69007, Lyon, France. alexia.kieffer@sanofi.com.

Abstract

Introduction: Respiratory syncytial virus (RSV) is associated with significant morbidity worldwide, especially among infants. We evaluated the potential impact of prophylactic nirsevimab, a monoclonal antibody, in infants experiencing their first RSV season, and the number of medically-attended lower respiratory tract infection episodes caused by RSV (RSV-MALRTI) in the USA.

Methods: We developed an age-structured, dynamic, deterministic compartmental model reflecting RSV natural history, incorporating USA demographic data and an age-specific contact matrix. We assumed either no effect of nirsevimab on transmission (scenario 1) or a 50% reduction of viral shedding (scenario 2). Model outcomes were RSV-MALRTIs, ICD-9 coded in the Marketscan^® database by month. We focused on age groups corresponding to the first 2 years of life, during seven RSV seasons (2008-2015).

Results: Scenario 1 illustrated the direct individual benefit when a universal immunization strategy is applied to all infants. In scenario 2, herd protection was observed across age groups, with 15.5% of all avoided cases due to reduced transmission; the greatest impact was in the youngest age group and a benefit was observed in those aged 65+ years.

Conclusion: These preliminary data suggest that single-dose nirsevimab will benefit infants experiencing their first RSV season, with a potential increase in effectiveness dependent on nirsevimab's mechanism of action.

Keywords: Disease transmission model; Immunization/prophylaxis strategy; Medically attended lower respiratory tract illness; Nirsevimab; RSV.