Lower Respiratory Tract Illness Research Articles

Respiratory syncytial virus co-opts hypoxia-inducible factor-1α-mediated glycolysis to favor the production of infectious virus.

Respiratory syncytial virus (RSV) is the leading etiological agent of lower respiratory tract illness. However, efficacious vaccines or antiviral drugs for treating RSV infections are currently not available. Indeed, RSV depends on host cells to provide energy needed to produce progeny virions. Glycolysis is a series of oxidative reactions used to metabolize glucose and provide energy to host cells. Therefore, glycolysis may be helpful for RSV infection. In this study, we show that RSV increases glycolysis by inducing the stabilization, transcription, translation, and activation of hypoxia-inducible factor (HIF)-1α in infected cells, which is important for the production of progeny RSV virions. This study contributes to understanding the molecular mechanism by which HIF-1α-mediated glycolysis controls RSV infection and reveals an effective target for the development of highly efficient anti-RSV drugs.

Utilization of cloves, Mentha, cinnamon and other essential oils in quick remedies of nasal congestion

With the rise of MDR bacteria and antibiotic resistance, there is a constant need to find novel medications and treatment methods for infectious diseases. One possible answer to this international issue is to study the antibacterial properties of essential oil (EOs), which are widely employed in modern cosmetics, healthcare, traditional medicine, and the food sector. Due to their multifaceted make-up, EOs operate in a complicated fashion. Infectious and inflammatory illnesses of the respiratory tract (RTDs) afflict a vast number of individuals of all ages all over the globe. Due to their low volatility, EOs are readily inhaled and spread throughout both the lower and upper respiratory tracts. In addition, they provide excellent therapy for infections of the respiratory tract (RTIs) owing to their antibacterial and anti-inflammatory properties. This article's goals are to (1) discuss the most common lower and upper respiratory tract illnesses and (2) illustrate the techniques used to ascertain the antibacterial capacity of EOs through gaseous contact. In addition to their anti-inflammatory effects, the mechanism by which EOs kill bacteria is examined. Recent in vivo animal investigations and clinical trials in humans are also described. In addition, patents are shown that discuss the use of EOs and its volatile components in the management of RTIs. The overarching goal of this study was to demonstrate the efficacy of EOs as antibacterial and anti-inflammatory medicines, hence reducing the discomfort associated with RTDs such as RTIs. John Wiley and Sons, Ltd., Copyright, 2015

Snapshots of ID Week 2022

Snapshots of ID Week 2022

Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants

BackgroundWhether vaccination during pregnancy could reduce the burden of respiratory syncytial virus (RSV)–associated lower respiratory tract illness in newborns and infants is uncertain.MethodsIn this phase 3, double-blind trial conducted in 18 countries, we randomly assigned, in a 1:1 ratio, pregnant women at 24 through 36 weeks’ gestation to receive a single intramuscular injection of 120 μg of a bivalent RSV prefusion F protein–based (RSVpreF) vaccine or placebo. The two primary efficacy end points were medically attended severe RSV-associated lower respiratory tract illness and medically attended RSV-associated lower respiratory tract illness in infants within 90, 120, 150, and 180 days after birth. A lower boundary of the confidence interval for vaccine efficacy (99.5% confidence interval [CI] at 90 days; 97.58% CI at later intervals) greater than 20% was considered to meet the success criterion for vaccine efficacy with respect to the primary end points.ResultsAt this prespecified interim analysis, the success criterion for vaccine efficacy was met with respect to one primary end point. Overall, 3682 maternal participants received vaccine and 3676 received placebo; 3570 and 3558 infants, respectively, were evaluated. Medically attended severe lower respiratory tract illness occurred within 90 days after birth in 6 infants of women in the vaccine group and 33 infants of women in the placebo group (vaccine efficacy, 81.8%; 99.5% CI, 40.6 to 96.3); 19 cases and 62 cases, respectively, occurred within 180 days after birth (vaccine efficacy, 69.4%; 97.58% CI, 44.3 to 84.1). Medically attended RSV-associated lower respiratory tract illness occurred within 90 days after birth in 24 infants of women in the vaccine group and 56 infants of women in the placebo group (vaccine efficacy, 57.1%; 99.5% CI, 14.7 to 79.8); these results did not meet the statistical success criterion. No safety signals were detected in maternal participants or in infants and toddlers up to 24 months of age. The incidences of adverse events reported within 1 month after injection or within 1 month after birth were similar in the vaccine group (13.8% of women and 37.1% of infants) and the placebo group (13.1% and 34.5%, respectively).ConclusionsRSVpreF vaccine administered during pregnancy was effective against medically attended severe RSV-associated lower respiratory tract illness in infants, and no safety concerns were identified. (Funded by Pfizer; MATISSE ClinicalTrials.gov number, NCT04424316.)

Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults

BackgroundRespiratory syncytial virus (RSV) infection causes considerable illness in older adults. The efficacy and safety of an investigational bivalent RSV prefusion F protein–based (RSVpreF) vaccine in this population are unknown.MethodsIn this ongoing, phase 3 trial, we randomly assigned, in a 1:1 ratio, adults (≥60 years of age) to receive a single intramuscular injection of RSVpreF vaccine at a dose of 120 μg (RSV subgroups A and B, 60 μg each) or placebo. The two primary end points were vaccine efficacy against seasonal RSV-associated lower respiratory tract illness with at least two or at least three signs or symptoms. The secondary end point was vaccine efficacy against RSV-associated acute respiratory illness.ResultsAt the interim analysis (data-cutoff date, July 14, 2022), 34,284 participants had received RSVpreF vaccine (17,215 participants) or placebo (17,069 participants). RSV-associated lower respiratory tract illness with at least two signs or symptoms occurred in 11 participants in the vaccine group (1.19 cases per 1000 person-years of observation) and 33 participants in the placebo group (3.58 cases per 1000 person-years of observation) (vaccine efficacy, 66.7%; 96.66% confidence interval [CI], 28.8 to 85.8); 2 cases (0.22 cases per 1000 person-years of observation) and 14 cases (1.52 cases per 1000 person-years of observation), respectively, occurred with at least three signs or symptoms (vaccine efficacy, 85.7%; 96.66% CI, 32.0 to 98.7). RSV-associated acute respiratory illness occurred in 22 participants in the vaccine group (2.38 cases per 1000 person-years of observation) and 58 participants in the placebo group (6.30 cases per 1000 person-years of observation) (vaccine efficacy, 62.1%; 95% CI, 37.1 to 77.9). The incidence of local reactions was higher with vaccine (12%) than with placebo (7%); the incidences of systemic events were similar (27% and 26%, respectively). Similar rates of adverse events through 1 month after injection were reported (vaccine, 9.0%; placebo, 8.5%), with 1.4% and 1.0%, respectively, considered by the investigators to be injection-related. Severe or life-threatening adverse events were reported in 0.5% of vaccine recipients and 0.4% of placebo recipients. Serious adverse events were reported in 2.3% of participants in each group through the data-cutoff date.ConclusionsRSVpreF vaccine prevented RSV-associated lower respiratory tract illness and RSV-associated acute respiratory illness in adults (≥60 years of age), without evident safety concerns. (Funded by Pfizer; RENOIR ClinicalTrials.gov number, NCT05035212; EudraCT number, 2021-003693-31.)

91. Establishing Proof of Concept for a Bivalent RSVpreF Subunit Vaccine for Maternal Immunization

Abstract Background Respiratory syncytial virus (RSV) is a major cause of infant morbidity and mortality worldwide and could be preventable by vaccination in pregnancy. Methods We conducted a randomized, placebo-controlled phase 2b trial evaluating safety, immunogenicity, and potential efficacy of a bivalent RSV prefusion F vaccine (RSVpreF) in pregnant women and their infants. Participants were randomized between 24- and 36-weeks’ gestation to receive 120 or 240 µg RSVpreF, with or without aluminum hydroxide, or placebo. Results This final analysis includes 579 women and 572 infants in 4 countries (Argentina, Chile, South Africa, and the US); 462 (79.8%) women received RSVpreF. Postvaccination reactions, most commonly injection site pain, fatigue, and myalgia, were generally mild-to-moderate. Adverse events (AEs) in the month following vaccination (maternal) or birth (infant) were mostly anticipated events in pregnancy and the neonatal period, respectively, and were similar between vaccine and placebo groups. No AEs were considered related to vaccination. For all RSVpreF groups, 50% neutralizing titers for both RSV-A and RSV-B rose sharply by 2 weeks after vaccination. At delivery occurring a mean of ∼8 weeks later, geometric mean titer (GMT) ratios for combined RSV-A/B between vaccine and placebo recipients’ infants were 10.9 to 13.6. Transplacental transfer ratios (all groups) were 1.39 to 1.83. Infant GMTs were higher in infants whose mothers had received RSVpreF versus placebo through 6 months of life; the estimated half-life of infant combined 50% RSV-A/B neutralizing titers was 41 days. Infants of women immunized across the range of assessed gestational ages had similar cord blood titers and transplacental transfer ratios. Observed efficacy (95% CI) against medically attended and severe medically attended infant RSV lower respiratory tract illness (LRTI) through 180 days in an exploratory analysis was 84.7% (21.5%, 97.6%) and 91.5% (-5.6%, 99.8%), respectively. Conclusion RSVpreF was well-tolerated in pregnant women, elicited robust neutralizing responses with efficient transplacental transfer, and has the potential to prevent infant RSV LRTI. Disclosures Eric A. F. Simões, MD, M.B., B.S., DCH, Abbvie: DSMB|Astra Zeneca: Grant/Research Support|Bill and Melinda Gates Foundation: Grant/Research Support|Bill and Melinda Gates Foundation: DSMB|GSK Inc.: DSMB|Johnson and Johnson: Grant/Research Support|Merck Inc: Advisor/Consultant|Merck Inc: Grant/Research Support|Nivavax: Grant/Research Support|Pfizer Inc: Advisor/Consultant|Pfizer Inc: Grant/Research Support|Regeneron: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Shabir A. Madhi, MBBCh, FCPaeds, MMed, PhD, AstraZeneca: Funding to institution for conduct of study Kimberly J. Center, M.D., Pfizer: Employee|Pfizer: Stocks/Bonds Jose M. Novoa Pizarro, MD, AstraZeneca: Grant/Research Support|Medimmune: Grant/Research Support|MSD: Grant/Research Support|Pfizer: Grant/Research Support|Regeneron: Grant/Research Support Kena A. Swanson, Ph.D., Pfizer: employee of Pfizer David Radley, MS, Pfizer: Employee|Pfizer: Stocks/Bonds Stephanie B. McGrory, B.S.N., Pfizer: Employee|Pfizer: Stocks/Bonds Emily A. Gomme, Ph.D., Pfizer: Stocks/Bonds Daniel A. Scott, MD, Pfizer: Employee|Pfizer: Stocks/Bonds Kathrin U. Jansen, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds William C. Gruber, MD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Alejandra C. Gurtman, M.D., Pfizer: employee of Pfizer.

LB748. Efficacy And Safety Of Bivalent Respiratory Syncytial Virus (RSVpreF) Vaccine In Older Adults

Abstract Background Respiratory syncytial virus (RSV) is an important cause of disease in older adults and is associated with high morbidity and mortality, especially in those with high-risk conditions. Illness can vary from mild upper respiratory tract symptoms to more severe lower respiratory tract disease. After over 50 years of research, there is now hope for an RSV vaccine for any population, including older adults. An investigational bivalent RSV A and B, stabilized RSV prefusion F subunit vaccine (RSVpreF) was assessed successfully in a pivotal phase 3 efficacy study in older adults. (NCT05035212). Methods The primary efficacy objective of this Phase 3, global, multicenter, randomized, double-blinded, placebo-controlled study was to evaluate the prevention of RSV associated lower respiratory tract illness (LRTI-RSV) in up to 40,000 adults ≥60 years of age during the first winter season (September 2021-June 2022). Two primary endpoints were tested sequentially – LRTI-RSV with ≥2 and ≥3 symptoms. A pre-planned efficacy interim analysis (IA) was to be conducted by an external Data Monitoring Committee (DMC) upon accrual of at least 29 cases of LRTI-RSV with ≥2 symptoms. With efficacy demonstrated for cases with ≥2 symptoms and sufficient cases with ≥ 3 symptoms accrued, an efficacy analysis of cases with ≥ 3 symptoms was to be conducted. The ongoing study is collecting additional safety and descriptive efficacy data. Results At the time of the IA, approximately 34,000 participants received either RSVpreF 120 µg (60 µg each of RSVpreF from RSV A and RSV B) or placebo (1:1 randomization). Forty-four LRTI-RSV cases with ≥2 symptoms were accrued with 11 cases in the RSVpreF group and 33 cases in the placebo group corresponding to a VE of 66.7% (96.66% CI: 28.8%, 85.8%). Sixteen LRTI-RSV cases with ≥3 symptoms were accrued with 2 cases in the RSVpreF group and 14 cases in the placebo group corresponding to a VE of 85.7% (96.66% CI: 32.0%, 98.7%). The investigational vaccine was well-tolerated with no safety concerns. Conclusion Despite unpredictable RSV activity due to the COVID-19 pandemic, the primary objective of the study was met demonstrating that RSVpreF had a favorable safety profile and was highly efficacious in preventing LRTI-RSV with ≥2 symptoms and ≥3 symptoms in older adults 60 years and older. Disclosures Edward E. Walsh, MD, Janssen: Honoraria|Merck: Grant/Research Support|Pfizer: Grant/Research Support Fernando Polack, MD, I-trials: Ownership Interest|Pfizer: Grant/Research Support Agnieszka Zareba, MD PhD, Pfizer: employee of Pfizer Ann R. Falsey, MD, BioFire Diagnostics: Grant/Research Support|Janssen: Grant/Research Support|Merck Sharp & Dohme: Grant/Research Support|Novavax: Advisor/Consultant|Pfizer: Grant/Research Support Gonzalo Perez Marc, MD, I-trials: Board Member|I-trials: Ownership Interest|Pfizer: Grant/Research Support Qin Jiang, PhD, Pfizer: employee of Pfizer Kathy Schneider, PhD, Pfizer: employee of Pfizer David Cooper, PhD, Pfizer: employee of Pfizer Maria Maddalena Lino, PhD, Pfizer: employee of Pfizer Annaliesa S. Anderson, PhD, Pfizer: employee of Pfizer|Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Katherin U Jensen, PhD, Pfizer: employee of Pfizer Kena A. Swanson, Ph.D., Pfizer: employee of Pfizer Alejandra C. Gurtman, M.D., Pfizer: employee of Pfizer William C. Gruber, MD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Beate Schmoele-Thoma, MD, Pfizer: employee of Pfizer.

Disease burden caused by respiratory syncytial virus compared with influenza among adults: a retrospective cohort study from Eastern Finland in 2017–2018

ObjectivesRespiratory syncytial virus (RSV) is one of the most important causes of lower respiratory tract illnesses. In this study, we examined the number and severity of RSV infections among adult...

Lower respiratory illnesses in childhood are associated with the presence of air trapping in early adulthood

Several factors occurring in early life, including lower respiratory tract illnesses (LRIs), are involved in determining lung structure and function in adulthood, but the effects of these factors on lung development remain largely unknown. Hereby, we evaluated the parameters from computed tomography (CT) scans performed at the age of 26 years in 39 subjects from the birth cohort of the Tucson Children's Respiratory Study (TCRS) in order to determine the relationship between early childhood factors and lung structural changes in young adult life. We found that participants with LRIs in childhood had increased air trapping at the age of 26 suggesting an association between childhood infections and lung development.

The emergence of human metapneumovirus G gene duplication in hospitalized patients with respiratory tract infection, India, 2016–2018

BackgroundHuman metapneumovirus (HMPV) belongs to the family Pneumoviridae. It is one of the emerging respiratory viruses causing both upper and lower respiratory tract illnesses. HMPV has two genotypes: A and B. These genotypes are classified into lineage A1, A2, B1 and B2. Lineage-A2 is further classified as A2a, A2b and A2c. Similarly, B2 is classified as B2a and B2b. Studies have shown the circulation of A2b, B1 and B2 lineages in India. However, a limited amount of data is available on the current circulating genotypes of HMPV in India.MethodsThroat swab samples positive for HMPV by real-time RT- PCR, archived at Manipal Institute of Virology as a part of a hospital-based acute febrile illness surveillance study, was used from April 2016 to August 2018 by purposive sampling method. We performed the conventional reverse transcriptase-polymerase chain reaction for twenty samples targeting the G gene and then subjected them to sequencing. Phylogenetic analysis was done using MEGA X software by the Maximum Likelihood method.ResultsAll the twenty sequences belonged to the A2c subgroup. Phylogenetic analysis showed that strains from the study have genetic relation with circulating strains in Japan, China and Croatia. Seven out of the twenty sequences showed 180-nucleotide duplication and eleven sequences showed 111-nucleotide duplication. Two sequences did not show any duplications.ConclusionIn the current study, we report that A2c is the sub-lineage in India from April 2016 to August 2018. This study is the first retrospective study reporting the circulation of the A2c sub-lineage among adults in India with 180- and 111-nucleotide duplications in the G gene of human metapneumovirus.

The burden and surveillance of RSV disease in young children in Belgium-expert opinion.

The Belgian population-based RSV surveillance should be improved, and a hospital-led reporting system should be put in place to enable the evaluation of the true burden of RSV disease in Belgium and to improve disease management in the future. • RSV bronchiolitis is a very important cause of infant hospitalization. • The burden of disease in the community is poorly studied and underestimated. • This expert opinion summarizes knowledge gaps and offers insights that allow improvement of local surveillance systems in order to establish a future-proof RSV surveillance system.

Expected Impact of Universal Immunization With Nirsevimab Against RSV-Related Outcomes and Costs Among All US Infants in Their First RSV Season: A Static Model.

BackgroundRespiratory syncytial virus (RSV) is associated with substantial morbidity in the United States, especially among infants. Nirsevimab, an investigational long-acting monoclonal antibody, was evaluated as an immunoprophylactic strategy for infants in their first RSV season and for its potential impact on RSV-associated, medically attended lower respiratory tract illness (RSV-MALRTI) and associated costs.MethodsA static decision-analytic model of the US birth cohort during its first RSV season was developed to estimate nirsevimab’s impact on RSV-related health events and costs; model inputs included US-specific costs and epidemiological data. Modelled RSV-related outcomes included primary care and emergency room visits, hospitalizations including intensive care unit admission and mechanical ventilations, and RSV-related mortality.ResultsUnder current standard of care, RSV caused 529 915 RSV-MALRTIs and 47 281 hospitalizations annually, representing $1.2 billion (2021 US dollars [USD]) in costs. Universal immunization of all infants with nirsevimab is expected to reduce 290 174 RSV-MALRTI, 24 986 hospitalizations, and expenditures of $612 million 2021 USD.ConclusionsAn all-infant immunization strategy with nirsevimab could substantially reduce the health and economic burden for US infants during their first RSV season. While this reduction is driven by term infants, all infants, including palivizumab-eligible and preterm infants, would benefit from this strategy.

An outbreak of human Rhinovirus-A21 infection in a psychiatric ward during COVID-19 pandemic.

A cluster of acute respiratory illnesses involving 12 inpatients and 3 healthcare workers occurred in a psychiatric ward. Eight of them were identified as HRV-A21. Fever and cough were the most common symptoms. The study also provides further evidence of the impact of HRV on lower respiratory tract illness.

Lung lavage inflammatory patterns and pathogen profiles in preschool children with problematic wheeze

Practicing clinicians regularly encounter the preschool child with intermittent episodes of wheeze. Preschool wheezing episodes account for a large burden of unscheduled ambulatory care visits and hospitalizations across the globe. Recurrent episodes of acute wheeze are often referred to as “problematic.” However, guidelines to treat these children are not based on solid evidence. There are few clinical trials applicable to real-world practice to direct treatment of problematic wheeze. 1 Bacharier LB Guilbert TW Mauger DT Boehmer S Beigelman A Fitzpatrick AM et al. Early administration of azithromycin and prevention of severe lower respiratory tract illnesses in preschool children with a history of such illnesses: a randomized clinical trial. JAMA. 2015; 314: 2034-2044 Crossref PubMed Scopus (193) Google Scholar , 2 Fitzpatrick AM Jackson DJ Mauger DT Boehmer SJ Phipatanakul W Sheehan WJ et al. Individualized therapy for persistent asthma in young children. J Allergy Clin Immunol. 2016; 138 (1608-1618.e12) Abstract Full Text Full Text PDF PubMed Scopus (164) Google Scholar , 3 Wallace A Sinclair O Shepherd M Neutze J Trenholme A Tan E et al. Impact of oral corticosteroids on respiratory outcomes in acute preschool wheeze: a randomised clinical trial. Arch Dis Child. 2021; 106: 339-344 Crossref PubMed Scopus (4) Google Scholar A helpful study by Bacharier et al 1 Bacharier LB Guilbert TW Mauger DT Boehmer S Beigelman A Fitzpatrick AM et al. Early administration of azithromycin and prevention of severe lower respiratory tract illnesses in preschool children with a history of such illnesses: a randomized clinical trial. JAMA. 2015; 314: 2034-2044 Crossref PubMed Scopus (193) Google Scholar found that a burst of azithromycin given early during an episode of virus-triggered wheeze in preschool children with a history of recurrent wheeze was effective in preventing the progression of symptoms. Azithromycin treatment was effective in not only the first but subsequent wheeze episodes over 1 year. Although guidelines on the management of preschool wheeze have been published, inconsistencies prevail as to the endorsement of azithromycin to treat acute exacerbations.

Human rhinovirus promotes STING trafficking to replication organelles to promote viral replication

Human rhinovirus (HRV), like coronavirus (HCoV), are positive-strand RNA viruses that cause both upper and lower respiratory tract illness, with their replication facilitated by concentrating RNA-synthesizing machinery in intracellular compartments made of modified host membranes, referred to as replication organelles (ROs). Here we report a non-canonical, essential function for stimulator of interferon genes (STING) during HRV infections. While the canonical function of STING is to detect cytosolic DNA and activate inflammatory responses, HRV infection triggers the release of STIM1-bound STING in the ER by lowering Ca2+, thereby allowing STING to interact with phosphatidylinositol 4-phosphate (PI4P) and traffic to ROs to facilitates viral replication and transmission via autophagy. Our results thus hint a critical function of STING in HRV viral replication and transmission, with possible implications for other RO-mediated RNA viruses.

Risk of persistent and new clinical sequelae among adults aged 65 years and older during the post-acute phase of SARS-CoV-2 infection: retrospective cohort study

ObjectiveTo characterize the risk of persistent and new clinical sequelae in adults aged ≥65 years after the acute phase of SARS-CoV-2 infection.DesignRetrospective cohort study.SettingUnitedHealth Group Clinical Research Database: deidentified administrative...

Frequency and Risk of Emergency Medical Service Interhospital Transportation of Patients With Acute Lower Respiratory Tract Illness During the COVID-19 Pandemic in the US

This study compares the frequency of hospital-to-hospital transportation events and associated life-threatening deterioration during transport among patients with acute lower respiratory tract illness during vs before the COVID-19 pandemic.

POSA197 Modeled Impact of Nirsevimab Against Respiratory Syncytial Virus (RSV) Among UK Infants Experiencing Their First RSV Season

Respiratory syncytial virus (RSV) is the leading cause of viral lower respiratory tract illness (LRTI) in young children and is associated with significant morbidity, especially among infants. Nirsevimab is a monoclonal antibody being developed as a passive immunization for the prevention of medically attended RSV-LRTI (RSV MALRTI). Understanding its health economic impact under different scenarios is important to determine the optimal implementation strategy to protect all infants entering their first RSV season.

POSB191 Modeled Impact of Nirsevimab Against Respiratory Syncytial Virus (RSV) Among French Infants Experiencing Their First RSV Season

Respiratory syncytial virus (RSV) is the leading cause of viral lower respiratory tract illness (LRTI) in young children and is associated with significant morbidity, especially among infants, and important burden on health care systems. Nirsevimab is a monoclonal antibody being developed as a passive immunization for the prevention of medically attended RSV-LRTI (RSV MALRTI). Understanding its health economic impact under different scenarios is important to determine the optimal implementation strategy to protect infants entering their first RSV season.

Breakthrough therapy designation of nirsevimab for the prevention of lower respiratory tract illness caused by respiratory syncytial virus infections (RSV)

ABSTRACT Introduction Respiratory syncytial virus (RSV) is a leading cause of serious lower respiratory tract infection (LRTI) in infants and young children. Palivizumab is an RSV-specific prophylactic for use in high-risk infants but treatment requires monthly injections and only modestly reduces hospitalization. Thus, new immunoprophylactic candidates are under development. Nirsevimab (MEDI8897) is a monoclonal antibody with an extended half-life developed to protect infants for an entire RSV season with a single dose. Areas Covered This review summarizes clinical trial data on nirsevimab. The authors introduce RSV and surface viral proteins involved in infection, then discuss the development and achievements of nirsevimab in clinical trials concluding with expert opinion. Information was compiled from PubMed, clinicaltrials.gov, and press releases from AstraZeneca and Sanofi. Expert opinion Nirsevimab (MEDI8897) is an RSV F protein monoclonal antibody and the next-generation RSV medicine having an extended half-life developed for the prevention of LRTI caused by RSV. Nirsevimab will supplant the current standard of care for RSV prevention. Importantly, nirsevimab requires a single dose to last the entire RSV season and may be given to term, preterm, and high-risk infants. However, even with nirsevimab approval there remains a need for an efficacious RSV vaccine and treatments.