Efficacy of nirsevimab against respiratory syncytial virus lower respiratory tract infections in preterm and term infants, and pharmacokinetic extrapolation to infants with congenital heart disease and chronic lung disease: a pooled analysis of randomised controlled trials

aChildren's Hospital Colorado, Aurora, CO, USA

bSouth African Medical Research Council Vaccines and Infectious Diseases Analytics Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

cAnn & Robert H Lurie Children's Hospital of Chicago and Northwestern University Feinberg School of Medicine, Chicago, IL, USA

dDr Georgi Stranski University Hospital, Pleven, Bulgaria

eUniversity Multiprofile Hospital for Active Treatment Sv Georgi Medical University, Plovdiv, Bulgaria

fQuironsalud Madrid University Hospital, Madrid, Spain

gQuirónsalud Málaga Hospital, Malaga, Spain

hState University of New York Upstate Medical University, Syracuse, NY, USA

iUniversity Hospital Severo Ochoa, Madrid, Spain

jBērnu Klīniskā Universitātes Slimnīca, Riga, Latvia

kHospices Civils de Lyon, Neonatal Intensive Care Units and CIC 1407, Lyon, France

lDepartment of Paediatrics and Child Health, Red Cross Children's Hospital, Cape Town, South Africa

mSA-MRC Unit on Child and Adolescent Health, University of Cape Town, Cape Town, South Africa

nBiometrics, Vaccines & Immune Therapies, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden

pClinical Development, Vaccines & Immune Therapies, Biopharmaceuticals R&D, AstraZeneca, Durham, NC, USA

qClinical Development, Vaccines & Immune Therapies, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA

qClinical Development, Vaccines & Immune Therapies, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA

rBiometrics, Vaccines & Immune Therapies, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA

oClinical Pharmacology and Quantitative Pharmacology, R&D, AstraZeneca, Gothenburg, Sweden

qClinical Development, Vaccines & Immune Therapies, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA

qClinical Development, Vaccines & Immune Therapies, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA

This manuscript has associated data in a repository. Data underlying the findings described in this manuscript, including individual de-identified participant data, protocols, and clinical trial documents, can be obtained in accordance with AstraZeneca's data sharing policy through Vivli.

In a phase 2b trial and the phase 3 MELODY trial, nirsevimab, an extended half-life, monoclonal antibody against respiratory syncytial virus (RSV), protected healthy infants born preterm or at full term against medically attended RSV lower respiratory tract infection (LRTI). In the MEDLEY phase 2–3 trial in infants at higher risk for severe RSV infection, nirsevimab showed a similar safety profile to that of palivizumab. The aim of the current analysis was to assess the efficacy of nirsevimab using a weight-banded dosing regimen in infants born between 29 weeks gestational age and full term.

Infants enrolled in the phase 2b and MELODY trials were randomised (2:1) to receive a single intramuscular injection of nirsevimab (infants weighing Table 1

Demographics and baseline characteristics (intention-to-treat population)

Efficacy of nirsevimab weight-band dose on different case definitions of medically attended LRTI to 150 days post-dose (intention-to-treat population)