Coadministration of Anti-Viral Monoclonal Antibodies With Routine Pediatric Vaccines and Implications for Nirsevimab Use: A White Paper

Comprehensive Summary of Safety Data on Nirsevimab in Infants and Children from All Pivotal Randomized Clinical Trials

BACKGROUND

Nirsevimab is approved in the US for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants during their first RSV season and in children aged ≤24 months who remain vulnerable to severe RSV disease through their second RSV season. We summarize a pre-specified analysis of nirsevimab safety data from three randomized controlled trials: Phase 2b (NCT02878330; healthy infants born ≥29 to <35 weeks' gestational age [wGA]); Phase 3 MELODY (NCT03979313; healthy infants born ≥35 wGA); and Phase 2/3 MEDLEY (NCT03959488; infants with congenital heart disease [CHD] and/or chronic lung disease of prematurity [CLD] or born ≤35 wGA).

METHODS

Participants (randomized 2:1) received a single intramuscular dose of nirsevimab or comparator (placebo, Phase 2b/MELODY; 5× once-monthly palivizumab, MEDLEY) before their first RSV season (recipients < 5 kg, nirsevimab 50 mg; ≥5 kg, nirsevimab 100 mg). In MEDLEY, children with CHD/CLD continued to a second RSV season: first-season nirsevimab recipients received nirsevimab 200 mg; first-season palivizumab recipients were re-randomized 1:1 to receive nirsevimab 200 mg or 5× once-monthly palivizumab.

RESULTS

The incidence, severity, and nature of AEs were similar across treatments (nirsevimab, n = 3184; placebo, n = 1284; palivizumab, n = 304). Most AEs were mild to moderate in severity, with ≥98% unrelated to treatment. AEs of special interest occurred infrequently (<1%): no anaphylaxis or thrombocytopenia were treatment-related, and no immune complex disease was reported. Deaths (incidence < 1.0%) were all unrelated to treatment.

CONCLUSIONS

A single dose per season of nirsevimab for the prevention of RSV disease had a favorable safety profile, irrespective of wGA or comorbidities.

Epidemiological and Genetic Characteristics of Respiratory Viral Coinfections with Different Variants of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)

This study aimed to determine the incidence and etiological, seasonal, and genetic characteristics of respiratory viral coinfections involving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Between October 2020 and January 2024, nasopharyngeal samples were collected from 2277 SARS-CoV-2-positive patients. Two multiplex approaches were used to detect and sequence SARS-CoV-2, influenza A/B viruses, and other seasonal respiratory viruses: multiplex real-time polymerase chain reaction (PCR) and multiplex next-generation sequencing. Coinfections of SARS-CoV-2 with other respiratory viruses were detected in 164 (7.2%) patients. The most common co-infecting virus was respiratory syncytial virus (RSV) (38 cases, 1.7%), followed by bocavirus (BoV) (1.2%) and rhinovirus (RV) (1.1%). Patients ≤ 16 years of age had the highest rate (15%) of mixed infections. Whole-genome sequencing produced 19 complete genomes of seasonal respiratory viral co-pathogens, which were subjected to phylogenetic and amino acid analyses. The detected influenza viruses were classified into the genetic groups 6B.1A.5a.2a and 6B.1A.5a.2a.1 for A(H1N1)pdm09, 3C.2a1b.2a.2a.1 and 3C.2a.2b for A(H3N2), and V1A.3a.2 for the B/Victoria lineage. The RSV-B sequences belonged to the genetic group GB5.0.5a, with HAdV-C belonging to type 1, BoV to genotype VP1, and PIV3 to lineage 1a(i). Multiple amino acid substitutions were identified, including at the antibody-binding sites. This study provides insights into respiratory viral coinfections involving SARS-CoV-2 and reinforces the importance of genetic characterization of co-pathogens in the development of therapeutic and preventive strategies.

Safety and Efficacy of Nirsevimab in a Universal Prevention Program of Respiratory Syncytial Virus Bronchiolitis in Newborns and Infants in the First Year of Life in the Valle d'Aosta Region, Italy, in the 2023-2024 Epidemic Season

Respiratory syncytial virus (RSV) bronchiolitis remains a significant global health burden, particularly in newborns and infants during their first year of life. The quest for an effective preventive strategy against RSV has long been sought, and recent developments have shown promise in the form of nirsevimab, a monoclonal antibody specifically designed for RSV prophylaxis. Valle d'Aosta was the first Italian region to propose universal prophylaxis with nirsevimab for newborns and infants in their first epidemic season as early as 2023-2024. This study describes the effectiveness and safety of the universal prevention program of RSV bronchiolitis using the monoclonal antibody nirsevimab in children resident in Valle d'Aosta born during the 2023-2024 epidemic season. There were 556 neonates born from 1 May 2023 to 15 February 2024. The risk of hospitalization for RSV bronchiolitis in 2023-2024 was 3.2%, compared to 7% in the 2022-2023 epidemic season (p < 0.001). After the start of the prophylaxis campaign with nirsevimab, the risk of hospitalization was 8.3% in the sample of infants who did not adhere to the prophylaxis, while no child in the sample of those treated (p < 0.001) was hospitalized for bronchiolitis. Few mild transient side effects were reported. This study shows the efficacy and safety of universal prophylaxis with nirsevimab in neonates, making Valle d'Aosta the first Italian region to offer universal prophylaxis to newborns without risk factors for RSV complications. Future research could further explore its long-term impact and cost-effectiveness.

Formulary Drug Reviews: Nirsevimab

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Nirsevimab: A Review

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in people of all ages and is the leading cause of hospitalization among infants in the United States. The year 2023 was exciting for RSV prevention. The Food and Drug Administration (FDA) approved 3 new tools for preventing severe lower respiratory tract RSV infections in infants, young children, and elderly persons. In May 2023, the FDA approved 2 vaccines, RSVpreF3 (Arexvy™, GSK) and RSVpreF (Abrysvo™, Pfizer), for adults ages 60 years or older to be given as a single-dose intramuscular injection. July 2023 brought the approval of the first long-acting monoclonal antibody nirsevimab (Beyfortus™, Sanofi and AstraZeneca) for the prevention of RSV disease in infants and young children. Then in August, the FDA approved a vaccine (Abrysvo™, Pfizer) to be given to pregnant women to protect their newborns through passive immunity. This article focuses on nirsevemab that has been recommended by the Advisory Committee on Immunization Practices (ACIP) and American Academy of Pediatrics (AAP) to be administered for all infants <8 months of age and for children 8 to 19 months of age who are at increased risk for severe RSV disease.

Respiratory Syncytial Virus Vaccines: A Review of the Candidates and the Approved Vaccines

Respiratory syncytial virus (RSV) is responsible for a significant proportion of global morbidity and mortality affecting young children and older adults. In the aftermath of formalin-inactivated RSV vaccine development, the effort to develop an immunizing agent was carefully guided by epidemiologic and pathophysiological evidence of the virus, including various vaccine technologies. The pipeline of RSV vaccine development includes messenger ribonucleic acid (mRNA), live-attenuated (LAV), subunit, and recombinant vector-based vaccine candidates targeting different virus proteins. The availability of vaccine candidates of various technologies enables adjustment to the individualized needs of each vulnerable age group. Arexvy® (GSK), followed by Abrysvo® (Pfizer), is the first vaccine available for market use as an immunizing agent to prevent lower respiratory tract disease in older adults. Abrysvo is additionally indicated for the passive immunization of infants by maternal administration during pregnancy. This review presents the RSV vaccine pipeline, analyzing the results of clinical trials. The key features of each vaccine technology are also mentioned. Currently, 24 vaccines are in the clinical stage of development, including the 2 licensed vaccines. Research in the field of RSV vaccination, including the pharmacovigilance methods of already approved vaccines, promotes the achievement of successful prevention.

Use of Nirsevimab for the Prevention of Respiratory Syncytial Virus Disease Among Infants and Young Children: Recommendations of the Advisory Committee on Immunization Practices - United States, 2023

Respiratory syncytial virus (RSV) is the leading cause of hospitalization among U.S. infants. In July 2023, the Food and Drug Administration approved nirsevimab, a long-acting monoclonal antibody, for passive immunization to prevent RSV-associated lower respiratory tract infection among infants and young children. Since October 2021, the Advisory Committee on Immunization Practices (ACIP) Maternal and Pediatric RSV Work Group has reviewed evidence on the safety and efficacy of nirsevimab among infants and young children. On August 3, 2023, ACIP recommended nirsevimab for all infants aged <8 months who are born during or entering their first RSV season and for infants and children aged 8-19 months who are at increased risk for severe RSV disease and are entering their second RSV season. On the basis of pre-COVID-19 pandemic patterns, nirsevimab could be administered in most of the continental United States from October through the end of March. Nirsevimab can prevent severe RSV disease among infants and young children at increased risk for severe RSV disease.

Monoclonal antibodies for prophylaxis and therapy of respiratory syncytial virus, SARS-CoV-2, human immunodeficiency virus, rabies and bacterial infections: an update from the World Association of Infectious Diseases and Immunological Disorders and the Italian Society of Antinfective Therapy

Monoclonal antibodies (mABs) are safe and effective proteins produced in laboratory that may be used to target a single epitope of a highly conserved protein of a virus or a bacterial pathogen. For this purpose, the epitope is selected among those that play the major role as targets for prevention of infection or tissue damage. In this paper, characteristics of the most important mABs that have been licensed and used or are in advanced stages of development for use in prophylaxis and therapy of infectious diseases are discussed. We showed that a great number of mABs effective against virus or bacterial infections have been developed, although only in a small number of cases these are licensed for use in clinical practice and have reached the market. Although some examples of therapeutic efficacy have been shown, not unlike more traditional antiviral or antibacterial treatments, their efficacy is significantly greater in prophylaxis or early post-exposure treatment. Although in many cases the use of vaccines is more effective and cost-effective than that of mABs, for many infectious diseases no vaccines have yet been developed and licensed. Furthermore, in emergency situations, like in epidemics or pandemics, the availability of mABs can be an attractive adjunct to our armament to reduce the impact. Finally, the availability of mABs against bacteria can be an important alternative, when multidrug-resistant strains are involved.

New strategies for the prevention of respiratory syncytial virus (RSV)

Respiratory Syncytial Virus (RSV) is the main cause of lower respiratory tract infections (LRTIs) in newborns in the first two years of life. RSV disease has a traditional seasonal trend, with an onset and offset, duration and peak. Prematurity, male gender, bronchopulmonary dysplasia (BPD), critical congenital cardiovascular disorders (CCHD), neuromuscular diseases, congenital and inherited airways anatomical anomalies are the main risk factors for increased severity of this infection. RSV infection is associated with negative long-term respiratory outcomes, with excess of morbidity, resulting in reduced quality of life of the infected children and representing a burden for the healthcare costs and resources. Despite all the efforts, prevention remains, to date, the most effective strategy to reduce RSV-related morbidity. Among the current prevention strategies, strict hygiene, breastfeeding and passive immunization with the monoclonal antibody Palivizumab are the cornerstone. In the next future, it is likely that new possibilities of prevention will add, including use of more potent and longer-acting monoclonal antibodies, implementation of maternal vaccination in pregnancy, and active immunization in children. The purpose of this review is to provide an overview of the main current and future prevention strategies against RSV.

Parental knowledge about respiratory syncytial virus (RSV) and attitudes to infant immunization with monoclonal antibodies

BACKGROUND

Ninety percent of all children are infected with respiratory syncytial virus (RSV) within their first two years of life. RSV is the main cause behind hospitalization of infants with lower respiratory tract infections. A new monoclonal antibody (mAb) immunization may prevent RSV in all infants. This cross-national study aimed to examine parental knowledge about RSV and attitudes to such RSV immunization.

RESEARCH DESIGN AND METHODS

Based on a literature study, a questionnaire was designed and applied in a survey carried out in China, France, Germany, Italy, Japan, Spain, the UK, and the US. Eligible respondents were expecting their first baby or parents of children <24 months old who were open to vaccination.

RESULTS

Parental acceptance of immunizations relies on perceptions of the preventable disease. In 5627 parents, only 35% reported basic or good level of knowledge about RSV. Recommendation from health care professionals and inclusion in immunization programs were crucial to their acceptance of RSV immunization. If recommended and informed about its efficacy and safety, most parents would accept RSV mAb immunization for their infants.

CONCLUSIONS

Infant RSV infections are highly prevalent, yet parental awareness of RSV is poor. Country variations call for targeted communication about RSV and immunization.