Balanced on the Biggest Wave: Nirsevimab for Newborns

Respiratory syncytial virus (RSV) is the leading cause of hospitalization in infancy in the United States. Nearly all infants are infected by 2 years of age, with bronchiolitis requiring hospitalization often occurring in previously healthy children and long-term consequences of severe disease including delayed speech development and asthma. Incomplete passage of maternal immunity and a high degree of genetic variability within the virus contribute to morbidity and have also prevented successful neonatal vaccine development. Monoclonal antibodies reduce the risk of hospitalization from severe RSV disease, with palivizumab protecting high-risk newborns with comorbidities including chronic lung disease and congenital heart disease. Unfortunately, palivizumab is costly and requires monthly administration of up to five doses during the RSV season for optimal protection.Rapid advances in the past two decades have facilitated the identification of antibodies with broad neutralizing activity and allowed manipulation of their genetic code to extend half-life. These advances have culminated with nirsevimab, a monoclonal antibody targeting the Ø antigenic site on the RSV prefusion protein and protecting infants from severe disease for an entire 5-month season with a single dose. Four landmark randomized controlled trials, the first published in July 2020, have documented the efficacy and safety of nirsevimab in healthy late-preterm and term infants, healthy preterm infants, and high-risk preterm infants and those with congenital heart disease. Nirsevimab reduces the risk of RSV disease requiring medical attention (number needed to treat [NNT] 14-24) and hospitalization (NNT 33-63) with rare mild rash and injection site reactions. Consequently, the Centers for Disease Control and Prevention has recently recommended nirsevimab for all infants younger than 8 months of age entering or born during the RSV season and high-risk infants 8-19 months of age entering their second season. Implementing this novel therapy in this large population will require close multidisciplinary collaboration. Equitable distribution through minimizing barriers and maximizing uptake must be prioritized.

Palivizumab prophylaxis in preterm infants and subsequent wheezing/asthma: 10-year follow-up study

BACKGROUND

Respiratory syncytial virus (RSV) causes not only infantile recurrent wheezing but also the development of asthma. To investigate whether palivizumab, an anti-RSV monoclonal antibody, prophylaxis given to preterm infants during the first RSV season reduces the incidence of subsequent recurrent wheezing and/or development of asthma, at 10 years of age.

METHODS

We conducted an observational prospective multicenter (52 registered hospitals in Japan) case-control study in preterm infants with a gestational age between 33 and 35 weeks followed for 6 years. During the 2007-2008 RSV season, the decision to administer palivizumab was made based on standard medical practice (SCELIA study). Here, we followed these subjects until 10 years of age. Parents of study subjects reported the patients' physician's assessment of recurrent wheezing/asthma, using a report card and a novel mobile phone-based reporting system using the internet. The relationship between RSV infection and asthma development, as well as the relationship between other factors and asthma development, were investigated.

RESULTS

Of 154 preterm infants enrolled, 113 received palivizumab during the first year of life. At 10 years, although both recurrent wheezing and development of asthma were not significantly different between the treated and untreated groups, maternal smoking with aeroallergen sensitization of the patients was significantly correlated with physician-diagnosed asthma.

CONCLUSIONS

In contrast to the prior study results at 6 years, by 10 years palivizumab prophylaxis had no impact on recurrent wheezing or asthma, but there was a significant correlation between maternal passive smoking with aeroallergen sensitization and development of asthma by 10 years of age.

Efficacy of Palivizumab Immunoprophylaxis for Reducing Severe RSV Outcomes in Children with Immunodeficiencies: A Systematic Review

BACKGROUND

Palivizumab is recommended for prevention of severe respiratory syncytial virus (RSV) disease in immunocompromised children, despite a lack of strong supporting evidence. The recent approval of substitute RSV-neutralizing monoclonal antibodies against RSV, offers an opportunity to synthesize the most current evidence supporting the palivizumab standard of care.

OBJECTIVE

To evaluate the efficacy of palivizumab in preventing acute respiratory tract infection- or RSV-related hospitalization, or mortality in immunocompromised children.

METHODS

We searched Ovid MEDLINE and EMBASE for published clinical studies that investigated outcomes of palivizumab use in children. We included clinical trials, cohort studies, and case-control studies. The primary outcomes were RSV-related or respiratory viral infection-related hospitalizations, or RSV-related mortality. This systematic review was registered in PROSPERO (ID CRD42021248619) and is reported in accordance with the PRISMA guidelines.

RESULTS

From the 1993 records, six studies were eligible and included, for a total of 625 immunocompromised children with an heterogeneous composition of primary and acquired immunodeficiencies enrolled from palivizumab programs. There were no intervention studies. None of the studies included a control group. RSV hospitalizations were infrequent (0%-3.1% of children). Most children included received palivizumab, although one study (n = 56) did not specify how many received palivizumab. RSV mortality was neither observed, in three studies, nor reported, in three other studies.

CONCLUSIONS

The evidence supporting the use of palivizumab for prevention of severe RSV disease in immunocompromised children remains extremely limited and appears insufficient to justify prioritizing this intervention as the current standard of care over alternative interventions.

Nirsevimab Immunization to Prevent Respiratory Syncytial Virus-Associated Lower Respiratory Tract Infections in Infants and Children up to 24 Months of Age

Respiratory syncytial virus (RSV) infects nearly all infants in their first year of life and is the leading cause of hospitalization for infants younger than 1 year of age in the United States. Historically, the only option for RSV prevention was palivizumab. However, not all infants are eligible for palivizumab, it requires multiple doses per RSV season, and it is costly. In July 2023, the U.S. Food and Drug Administration approved nirsevimab for the prevention of RSV-associated lower respiratory tract infections for all infants. Nirsevimab inhibits RSV from fusing to cellular membranes and thereby neutralizes the virus in the body. Nirsevimab is expected to significantly reduce the health and economic burdens of RSV. This article provides an overview of nirsevimab, potential adverse effects, and implications for nursing practice.

Corrigendum: Wastewater-based surveillance identifies start to the pediatric respiratory syncytial virus season in two cities in Ontario, Canada

[This corrects the article DOI: 10.3389/fpubh.2023.1261165.].

Efficacy and Safety of Palivizumab as a Prophylaxis for Respiratory Syncytial Virus (RSV) Disease: An Updated Systemic Review and Meta-Analysis

This systematic review and meta-analysis aimed to summarize the current evidence regarding the efficacy and safety of palivizumab as a prophylaxis for respiratory syncytial virus (RSV) disease. We searched MEDLINE via PubMed, Scopus, Cochrane, Web of Science, Embase, and Science Direct from inception till November 2023. Studies that assessed the efficacy and safety of palivizumab in infants aged between 28 days and three months of age were included. We analyzed the data using Review Manager 5.4 software, with results pooled across studies and expressed as risk ratios (RR) with 95% confidence intervals (CI). A total of 10 studies were included. The effect estimates favored palivizumab over placebo regarding the hospitalization for RSV infection (RR=0.51, 95% CI: 0.40 to 0.65; P<0.00001) and ICU admission (RR=0.49, 95% CI: 0.30 to 0.81; P=0.005). On the other hand, the effect estimate showed no significant difference between palivizumab and placebo regarding all-cause mortality (RR=0.69, 95% CI: 0.42 to 1.15; P=0.16), lower respiratory tract infection (RR=0.42, 95% CI: 0.11 to 1.69; P=0.22), and need for mechanical ventilation (RR=0.75, 95% CI: 0.34 to 1.67; P=0.48). Palivizumab can be considered a prophylaxis for RSV disease in young children as it is safe, well-tolerated, and effective in reducing RSV hospitalizations. However, further research through high-quality randomized controlled trials is required to determine its efficacy as a therapeutic agent for established RSV infections.

Aerosol Delivery of Palivizumab in a Neonatal Lamb Model of Respiratory Syncytial Virus Infection

(1) Background: Palivizumab has been an approved preventative monoclonal antibody for respiratory syncytial virus (RSV) infection for over two decades. However, due to its high cost and requirement for multiple intramuscular injections, its use has been limited mostly to high-income countries. Following our previous study showing the successful lung deposition of aerosolised palivizumab in lambs, this current study evaluated the "proof-of-principle" effect of aerosolised palivizumab delivered as a therapeutic to neonatal lambs following RSV infection. (2) Methods: Neonatal lambs were intranasally inoculated with RSV-A2 on day 0 (day 3 post-birth) and treated with aerosolised palivizumab 3 days later (day 3 post-inoculation). Clinical symptoms, RSV viral load and inflammatory response were measured post-inoculation. (3) Results: Aerosolised therapeutic delivery of palivizumab did not reduce RSV viral loads in the nasopharynx nor the bronchoalveolar lavage fluid, but resulted in a modest reduction in inflammatory response at day 6 post-inoculation compared with untreated lambs. (4) Conclusions: This proof-of-principle study shows some evidence of aerosolised palivizumab reducing RSV inflammation, but further studies using optimized protocols are needed in order to validate these findings.

The rapidly changing landscape of respiratory syncytial virus prophylaxis

The introduction of nirsevimab (a respiratory syncytial virus [RSV] monoclonal antibody that can protect for minimum 5 months with a single dose) and RSV maternal vaccines to protect young infants has the potential to dramatically decrease RSV hospitalizations in Canada. However, there remain many unanswered questions before optimal use of these products can be assured.

Respiratory-syncytial virus immunoprophylaxis on asthma symptoms development in prematurity with bronchopulmonary dysplasia

Background

Infants with respiratory-syncytial virus bronchiolitis hospitalization are more likely to develop wheezing and subsequent asthma. Reportedly, palivizumab prophylaxis effectively prevents respiratory-syncytial virus hospitalization in high-risk children-such as premature infants or infants with bronchopulmonary dysplasia (BPD).

Objective

We sought to explore the effect of respiratory-syncytial virus immunoprophylaxis on the risk of asthma development in premature infants with BPD in subtropical areas.

Methods

This case-control study included preterm children with BPD born at Mackay Memorial Hospital, Taipei, Taiwan, from 1999 to 2015. Overall, medical records of 616 eligible participants were retrospectively collected from their birth to the time they attained an age of 5 to 20 years. The primary outcome was onset of active asthma.

Results

Overall, 576 consecutive cases met the inclusion criteria. Of these, 306 (53.2%) patients had palivizumab exposure and 191 (33.2%) were diagnosed with asthma. Patients with history of respiratory-syncytial virus bronchiolitis hospitalization had a higher risk of developing asthma in the future (adjusted odds ratio, 3.77; 95% CI, 2.30-6.20, P < .001; hazard ratio, 2.56; 95% CI, 1.81-3.62, P < .001). Palivizumab prophylaxis reduced future asthma development through the inhibition of respiratory-syncytial virus bronchiolitis hospitalization (coefficient, -0.021; 95% CI, -0.031 to -0.011, P = .027). Asthmatic children who received palivizumab immunoprophylaxis had a lesser active asthma duration than those who did not (P = .005).

Conclusions

Children with BPD with hospitalization for respiratory-syncytial virus bronchiolitis had higher risk of developing asthma compared with those without respiratory-syncytial virus infection. Prophylactic palivizumab might reduce later asthma development through inhibition of respiratory-syncytial virus bronchiolitis hospitalization. For those already developing asthma, palivizumab could reduce active asthma duration.

Potential Benefits of Expanded Palivizumab in American Indian Children Under the Age of 2 Years

Severe respiratory syncytial virus (RSV) infections disparately impact American Indian communities. We implemented a program that expanded palivizumab to all children under 2 years of age that led to significant reductions in RSV infections and hospitalizations for both high-risk and non-high-risk recipients in a rural American Indian community in Eastern Arizona.

Wastewater-based surveillance identifies start to the pediatric respiratory syncytial virus season in two cities in Ontario, Canada

Introduction

Detection of community respiratory syncytial virus (RSV) infections informs the timing of immunoprophylaxis programs and hospital preparedness for surging pediatric volumes. In many jurisdictions, this relies upon RSV clinical test positivity and hospitalization (RSVH) trends, which are lagging indicators. Wastewater-based surveillance (WBS) may be a novel strategy to accurately identify the start of the RSV season and guide immunoprophylaxis administration and hospital preparedness.

Methods

We compared citywide wastewater samples and pediatric RSVH in Ottawa and Hamilton between August 1, 2022, and March 5, 2023. 24-h composite wastewater samples were collected daily and 5 days a week at the wastewater treatment facilities in Ottawa and Hamilton, Ontario, Canada, respectively. RSV WBS samples were analyzed in real-time for RSV by RT-qPCR.

Results

RSV WBS measurements in both Ottawa and Hamilton showed a lead time of 12 days when comparing the WBS data set to pediatric RSVH data set (Spearman's ρ = 0.90). WBS identify early RSV community transmission and declared the start of the RSV season 36 and 12 days in advance of the provincial RSV season start (October 31) for the city of Ottawa and Hamilton, respectively. The differing RSV start dates in the two cities is likely associated with geographical and regional variation in the incidence of RSV between the cities.

Discussion

Quantifying RSV in municipal wastewater forecasted a 12-day lead time of the pediatric RSVH surge and an earlier season start date compared to the provincial start date. These findings suggest an important role for RSV WBS to inform regional health system preparedness, reduce RSV burden, and understand variations in community-related illness as novel RSV vaccines and monoclonal antibodies become available.

Review of the Safety, Efficacy and Tolerability of Palivizumab in the Prevention of Severe Respiratory Syncytial Virus (RSV) Disease

Respiratory Syncytial Virus (RSV) is a major global cause of childhood morbidity and mortality. Palivizumab, a monoclonal antibody that provides passive immunity against RSV, is currently licensed for prophylactic use in specific "high-risk" populations, including congenital heart disease, bronchopulmonary dysplasia and prematurity. Available research suggests palivizumab use in these high-risk populations can lead to a reduction in RSV-related hospitalization. However, palivizumab has not been demonstrated to reduce mortality, adverse events or length of hospital stay related to RSV. In this article, we review the management of RSV, indications for palivizumab prophylaxis, the safety, cost-effectiveness and efficacy of this preventative medication, and emerging therapeutics that could revolutionize future prevention of this significant pathogen.

Safety of Re-dosing Nirsevimab Prior to RSV Season 2 in Children With Heart or Lung Disease

In children with congenital heart disease and/or chronic lung disease entering their second respiratory syncytial virus (RSV) season, 200 mg nirsevimab had a similar safety profile to that of palivizumab and resulted in nirsevimab serum exposures associated with efficacy in healthy infants, supporting efficacy in this population at risk of severe RSV disease.

Immune Prophylaxis Targeting the Respiratory Syncytial Virus (RSV) G Protein

The respiratory syncytial virus (RSV) causes significant respiratory disease in young infants and the elderly. Immune prophylaxis in infants is currently limited to palivizumab, an anti-RSV fusion (F) protein monoclonal antibody (mAb). While anti-F protein mAbs neutralize RSV, they are unable to prevent aberrant pathogenic responses provoked by the RSV attachment (G) protein. Recently, the co-crystal structures of two high-affinity anti-G protein mAbs that bind the central conserved domain (CCD) at distinct non-overlapping epitopes were solved. mAbs 3D3 and 2D10 are broadly neutralizing and block G protein CX3C-mediated chemotaxis by binding antigenic sites γ1 and γ2, respectively, which is known to reduce RSV disease. Previous studies have established 3D3 as a potential immunoprophylactic and therapeutic; however, there has been no similar evaluation of 2D10 available. Here, we sought to determine the differences in neutralization and immunity to RSV Line19F infection which recapitulates human RSV infection in mouse models making it useful for therapeutic antibody studies. Prophylactic (24 h prior to infection) or therapeutic (72 h post-infection) treatment of mice with 3D3, 2D10, or palivizumab were compared to isotype control antibody treatment. The results show that 2D10 can neutralize RSV Line19F both prophylactically and therapeutically, and can reduce disease-causing immune responses in a prophylactic but not therapeutic context. In contrast, 3D3 was able to significantly (p < 0.05) reduce lung virus titers and IL-13 in a prophylactic and therapeutic regimen suggesting subtle but important differences in immune responses to RSV infection with mAbs that bind distinct epitopes.

Impact of using the International Risk Scoring Tool on the cost-utility of palivizumab for preventing severe respiratory syncytial virus infection in Canadian moderate-to-late preterm infants

BACKGROUND AND OBJECTIVE

To assess the cost-utility of palivizumab versus no prophylaxis in preventing severe respiratory syncytial virus (RSV) infection in Canadian moderate-to-late preterm (32-35 weeks' gestational age) infants using an: i) International Risk Scoring Tool (IRST); ii) Canadian RST (CRST).

METHODS

A decision tree was developed to assess cost-utility. Infants assessed at moderate- and high-risk of RSV-related hospitalization (RSVH) by the IRST or CRST received palivizumab or no prophylaxis and then progressed to either: i) RSVH; ii) emergency room/outpatient medically attended RSV-infection (MARI); or, iii) were uninfected/non-medically attended. Infants admitted to intensive care could incur mortality (0.43%). Respiratory morbidity was accounted in all uninfected surviving infants for 6 years or 18 years (RSVH/MARI). Palivizumab efficacy (72.2% RSVH reduction) and hospital outcomes were from the Canadian CARESS, PICNIC and RSV-Quebec studies. Palivizumab costs (50mg: CAN$752; 100mg: $1,505) were calculated from Canadian birth statistics combined with a growth algorithm. Healthcare/payer and societal costs (May 2022; 1.5% discounting) were included.

RESULTS

Cost per quality-adjusted life year (QALY) was $29,789 with the IRST (0.79 probability of being <$50,000) and $15,833 with the CRST (0.96 probability). The model was most sensitive to utility scores, long-term sequelae, and palivizumab cost. Vial sharing improved the incremental cost-utility ratio (IRST: $22,319; CRST: $9,231).

CONCLUSIONS

Palivizumab was highly cost-effective (vs no prophylaxis) in Canadian moderate-to-late preterm infants using either the IRST or CRST. The IRST has fewer risk factors than the CRST (3 vs 7, respectively), captures more potential RSVHs (85% vs 54%) and provides another option to guide cost-effective RSV prophylaxis in Canada.

How has the SARS-CoV-2 pandemic changed the epidemiology and management of acute bronchiolitis?

OBJECTIVE

SARS-COV-2 pandemic profoundly impacted acute bronchiolitis epidemiology worldwide, especially respiratory syncytial virus (RSV) diffusion and the burden of disease, with remarkable implications on the management of health resources. We aimed to study the epidemiology and clinical course of bronchiolitis in the past 5 years in our region and to assess the trends that occurred during and after the SARS-COV-2 pandemic.

METHODS

We conducted an observational study including all children aged 0-2 years with bronchiolitis admitted to a tertiary children's hospital during the last 5 years. Demographic, clinical, and microbiological data were collected. Comparisons between patient subgroups were carried out.

RESULTS

A total of 647 patients admitted for bronchiolitis were included (median age 78 days). Molecular diagnostic tests were performed in 617 patients (95.4%) with RSV detected in 51.5% of patients in prepandemic years and 74.5% in pandemic years. Through the study period, we observed a progressive increase in the number of children requiring respiratory support, RSV infections, and children with a history of prematurity. Conversely, this was not true for mechanical ventilation, duration of respiratory support, intensive care unit admission, and length of stay.

CONCLUSIONS

Clinical course and epidemiology of bronchiolitis showed a significant change through the study years with a heavy impact during the 2021-2022 season. The increase in the number of patients requiring respiratory support, although not associated with an increase in mechanical ventilation, may be explained by the higher prevalence of RSV. The change in epidemiology highlights the importance of surveillance systems to monitor RSV circulation, to plan prophylactic strategies, and prepare healthcare systems.

Home Immunization with Palivizumab-A Randomized Pilot Study Describing Safety Aspects and Parents' Preferences

Among prematurely born infants and newborns with chronic conditions, a respiratory syncytial virus (RSV) infection may cause (re-)admission and later respiratory complications. Therapeutic protection is possible with monthly injections of a specific monoclonal antibody, palivizumab, during RSV season. Standard care is giving up to five injections in clinic-based settings. Immunization at home could be an alternative to standard care for vulnerable infants to reduce the number of revisits and associated risk of RSV infection. The aim of this randomized pilot trial was to evaluate safety aspects and explore parents' preferences of home versus hospital immunization with palivizumab during one RSV season. Immediate adverse events (AEs) were observed and registered by a pediatric specialist nurse. Late-onset AEs were reported by parents. Parents' perceptions were collected through a questionnaire and analyzed using content analysis. The study population consisted of 43 infants in 38 families. No immediate AEs occurred. Three late-onset AEs were reported in two infants in the intervention group. Three categories emerged in the content analysis: (1) protect and watch over the infant, (2) optimal health and well-being for the whole family, and (3) avoid suffering for the infant. The study results show that home immunization with palivizumab is feasible if safety aspects are considered and that parental involvement in the choice of place for immunization after a neonatal intensive care experience can be important.

Temporal-spatial analysis of hospitalizations for bronchiolitis in Brazil: prediction of epidemic regions and periods for immunization against the Respiratory Syncytial Virus

OBJECTIVE

Due to the high cost and short term of passive immunization against the respiratory syncytial virus, the main virus causing acute viral bronchiolitis, predicting epidemic regions and epidemic months is extremely important. The objective of this study is to identify both the month when the seasonal peak begins and Brazilian regions and states with the highest incidence of monthly hospitalizations due acute viral bronchiolitis.

METHODS

Based on data obtained from DATASUS, monthly hospitalization rates due acute viral bronchiolitis were calculated for every 10,000 live births to children under 12 months of age in all Brazilian states and the Federal District between 2000 and 2019. Seasonal autoregressive integrated moving average models were estimated to forecast monthly hospitalization rates in 2020.

RESULTS

A higher incidence of hospitalizations was found for male children, especially under six months of age. As for Brazilian regions, between 2000 and 2019, the South region registered the highest incidence of hospitalizations, followed by the Southeast, Midwest, North and Northeast regions, in this order. Considering the seasonal peak, the period between March and July 2020 comprised the highest expected hospitalization rates.

CONCLUSIONS

Palivizumab is suggested to be started between February/March and June/July for most Brazilian states, with the exception of Rio Grande do Sul, which, in addition to presenting the highest rates of hospitalizations for acute viral bronchiolitis per 10,000 live births, has the longest seasonal peak between May and September.

Anti-G protein antibodies targeting the RSV G protein CX3C chemokine region improve the interferon response

Background

Respiratory syncytial virus (RSV) is a poor inducer of antiviral interferon (IFN) responses which result in incomplete immunity and RSV disease. Several RSV proteins alter antiviral responses, including the non-structural proteins (NS1, NS2) and the major viral surface proteins, that is, fusion (F) and attachment (G) proteins. The G protein modifies the host immune response to infection linked in part through a CX3 C chemokine motif. Anti-G protein monoclonal antibodies (mAbs), that is, clones 3D3 and 2D10 that target the G protein CX3C chemokine motif can neutralize RSV and inhibit G protein-CX3CR1 mediated chemotaxis.

Objectives

Determine how monoclonal antibodies against the RSV F and G proteins modify the type I and III IFN responses to RSV infection.

Design

As the G protein CX3 C motif is implicated in IFN antagonism, we evaluated two mAbs that block G protein CX3C-CX3CR1 interaction and compared responses to isotype mAb control using a functional cellular assay and mouse model.

Methods

Mouse lung epithelial cells (MLE-15 cells) and BALB/c mice were infected with RSV Line19 F following prophylactic mAb treatment. Cell supernatant or bronchoalveolar lavage fluid (BALF) were assayed for types I and III IFNs. Cells were interrogated for changes in IFN-related gene expression.

Results

Treatment with an anti-G protein mAb (3D3) resulted in improved IFN responses compared with isotype control following infection with RSV, partially independently of neutralization, and this was linked to upregulated SOCS1 expression.

Conclusions

These findings show that anti-G protein antibodies improve the protective early antiviral response, which has important implications for vaccine and therapeutic design.

Plain Language Summary

RSV is a leading cause of respiratory disease in infants and the elderly. The only Food and Drug Administration-approved prophylactic treatment is limited to an anti-F protein monoclonal antibody (mAb), that is, palivizumab which has modest efficacy against RSV disease. Accumulating evidence suggests that targeting the RSV attachment (G) protein may provide improved protection from RSV disease. It is known that the G protein is an IFN antagonist, and IFN has been shown to be protective against RSV disease. In this study, we compared IFN responses in mouse lung epithelial (MLE-15) cells and in mice infected with RSV Line19 F treated with anti-G protein or anti-F protein mAbs. The levels of type I and III IFNs were determined. Anti-G protein mAbs improved the levels of IFNs compared with isotype-treated controls. These findings support the concept that anti-G protein mAbs mediate improved IFN responses against RSV disease, which may enable improved treatment of RSV infections.

Characterisation of RSV Fusion Proteins from South African Patients with RSV Disease, 2019 to 2020

Respiratory syncytial virus (RSV) is classified into RSV-A and RSV-B, which are further classified into genotypes based on variability in the G gene. The fusion (F) protein is highly conserved; however, variability within antigenic sites has been reported. This study aimed to characterise F proteins from RSV strains detected in South Africa from 2019 to 2020. Patients of all ages, from whom respiratory samples were submitted to the National Health Laboratory Service at Charlotte Maxeke Johannesburg Academic Hospital, South Africa during 2019 to 2020, were included. Complete RSV F genes were amplified for next-generation sequencing. MEGA X software was used for phylogenetic analysis. The overall prevalence of RSV was 5.8% (101/1734). Among 101 RSV positive samples only 69.3% (70/101) were available for characterization of the RSV F protein gene. Among cases included for F gene characterisation, viral co-infections were observed in 50% (35/70) and 25.7% (18/70) were admitted to intensive care units (ICU). About 74.2% (23/31) of F gene sequences cluster with other African NA1/ON1 genotypes. At antigenic site I, the V384I mutation was replaced by V384T in South African strains. The S275F mutation was seen in a single South African strain. The N120 N-linked glycosylation site was present in 25.8% (8/31) of RSV-A F proteins described in this study. For the first time, we detected the rare S275F mutation that is associated with palivizumab resistance.

Impact of immunoprophylaxis with palivizumab on respiratory syncytial virus infection in preterm infants less than 35 weeks in Colombian hospitals

OBJECTIVE

To evaluate the impact of immunoprophylaxis with palivizumab in preterm infants less than 35 weeks in terms of hospitalization rate, intensive care unit requirement, and mortality.

METHODS

A prospective cohort study was conducted at six Colombian hospitals. Preterm infants less than 35 weeks who received at least one dose of palivizumab during the first 6 months of life were included. The primary outcome was the hospitalization rate related to respiratory syncytial virus (RSV) infection.

RESULTS

A total of 222 newborns participated in the study; 204 (91.8%) completed the 6-month follow-up, and three died during the study. 88.7% received a second dose of palivizumab, 79.7% a third, 34.7% a fourth, and 25.2% a fifth. The nonadjusted incidence rate of RSV infection was 2.4%, and the overall RSV-positive hospitalization rate was 1.9%. The proportion of patients that required Neonatal Intensive Care Unit (NICU) and mechanical ventilation in relation to RSV infection was 1.4%. Discharge with home oxygen, pulmonary dysplasia, and being younger than 6 months were significantly associated with respiratory infection. Furthermore, exposition to cigarette smoke was the only factor associated with increased risk of hospitalization. The group that required hospitalization received fewer doses of palivizumab (p = 0.049). No discontinuation of treatment due to adverse events were reported. No death was judged to be related to palivizumab.

CONCLUSION

The hospitalization rate and the need for NICU admission were lower than those reported in the literature. In this real-life setting, palivizumab appears to be effective in preventing serious cases of RSV infection.

Respiratory syncytial virus, recurrent wheeze and asthma: A narrative review of pathophysiology, prevention and future directions

Globally, respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in young children, and the association between severe RSV disease and later recurrent wheeze and asthma is well established. Whilst a causal link between RSV and wheeze/asthma is not yet proven, immunological evidence suggests skewing towards a Th2-type response, and dampening of IFN-γ antiviral immunity during RSV infection underpins airway hyper-reactivity in a subset of susceptible children after RSV infection. Age at primary RSV infection, viral co-infection and genetic influences may act as effect-modifiers. Despite the significant morbidity and mortality burden of RSV disease in children, there is currently no licensed vaccine. Recent advancements in RSV preventatives, including long-acting monoclonal antibodies and maternal vaccinations, show significant promise and we are on the cusp of a new era in RSV prevention. However, the potential impact of RSV preventatives on subsequent wheeze and asthma remains unclear. The ongoing COVID-19 pandemic and associated public health measures have disrupted the usual seasonality of RSV. Whilst this has posed challenges for health-care services it has also enhanced our understanding of RSV transmission. The near absence of RSV cases during the first year of the pandemic in the context of strict public health measures has provided a rare opportunity to study the impact of delayed age of primary RSV infection on asthma prevalence. In this review, we summarise current understanding of the association between RSV, recurrent wheeze and asthma with a focus on pathophysiology, preventative strategies and future research priorities.

Cost Savings Without Increased Risk of Respiratory Hospitalization for Preterm Children after the 2014 Palivizumab Policy Update

OBJECTIVE

 Our objective was to compare rates of hospitalizations for respiratory illnesses in preterm and full-term (FT) children for 4 years before and after the 2014 update to the American Academy of Pediatrics (AAP) respiratory syncytial virus (RSV) immunoprophylaxis guidance, which restricted eligibility among infants born at 29 to 34 weeks in the first winter and all preterm infants in the second winter after neonatal discharge.

STUDY DESIGN

 We conducted pre-post and interrupted time series analyses on claims data from a commercial national managed care plan. We compared the number of RSV and all respiratory hospital admissions in the first and second RSV seasons after neonatal discharge among a cohort of preterm children, regardless of palivizumab status, in the 4 years before and after the implementation of the 2014 palivizumab eligibility change. A FT group was included for reference.

RESULTS

 The cohort included 821 early preterm (EP, <29 weeks), 4,790 moderate preterm (MP, 29-34 weeks), and 130,782 FT children. Palivizumab use after the policy update decreased among MP children in the first and second RSV seasons after neonatal discharge, without any change in the odds of hospitalization with RSV or respiratory illness. For the EP group, there was no change in the rate of palivizumab or the odds of hospitalization with RSV or respiratory illness after the policy update. For the FT group, there was a slight decrease in odds of hospitalization post-2014 after the policy update. The interrupted time series did not reveal any secular trends over time in hospitalization rates among preterm children. Following the policy change, there were cost savings for MP children in the first and second RSV seasons, when accounting for the cost of hospitalizations and the cost of palivizumab.

CONCLUSION

 Hospitalizations for RSV or respiratory illness did not increase, and cost savings were obtained after the implementation of the 2014 AAP palivizumab prophylaxis policy.

KEY POINTS

· Palivizumab use decreased among children born moderate preterm (29 to34 weeks) after the 2014 palivizuamb policy update.. · There was no change in odds of hospitalization with respiratory syncitial virus or respiratory illness among preterm infants after the policy update when compared to before.. · There were cost savings, when accounting for the cost of hospitalizations and the cost of palivizumab, after the policy update among children born moderate preterm..

RSV Prevention in All Infants: Which Is the Most Preferable Strategy?

Respiratory syncytial virus (RSV) causes a spectrum of respiratory illnesses in infants and young children that may lead to hospitalizations and a substantial number of outpatient visits, which result in a huge economic and healthcare burden. Most hospitalizations happen in otherwise healthy infants, highlighting the need to protect all infants against RSV. Moreover, there is evidence on the association between early-life RSV respiratory illness and recurrent wheezing/asthma-like symptoms As such, RSV is considered a global health priority. However, despite this, the only prevention strategy currently available is palivizumab, a monoclonal antibody (mAb) indicated in a subset of preterm infants or those with comorbidities, hence leaving the majority of the infant population unprotected against this virus. Therefore, development of prevention strategies against RSV for all infants entering their first RSV season constitutes a large unmet medical need. The aim of this review is to explore different immunization approaches to protect all infants against RSV. Prevention strategies include maternal immunization, immunization of infants with vaccines, immunization of infants with licensed mAbs (palivizumab), and immunization of infants with long-acting mAbs (e.g., nirsevimab, MK-1654). Of these, palivizumab use is restricted to a small population of infants and does not offer a solution for all-infant protection, whereas vaccine development in infants has encountered various challenges, including the immaturity of the infant immune system, highlighting that future pediatric vaccines will most likely be used in older infants (>6 months of age) and children. Consequently, maternal immunization and immunization of infants with long-acting mAbs represent the two feasible strategies for protection of all infants against RSV. Here, we present considerations regarding these two strategies covering key areas which include mechanism of action, "consistency" of protection, RSV variability, duration of protection, flexibility and optimal timing of immunization, benefit for the mother, programmatic implementation, and acceptance of each strategy by key stakeholders. We conclude that, based on current data, immunization of infants with long-acting mAbs might represent the most effective approach for protecting all infants entering their first RSV season.

Respiratory syncytial virus bronchiolitis in congenital diaphragmatic hernia: A systematic review of prevalence rates and palivizumab prophylaxis

BACKGROUND

The seasonality of respiratory syncytial virus (RSV) epidemics have been disrupted during the COVID-19 pandemic, possibly because of lockdowns and social restrictions reducing viral transmission. Given uncertainties around the severity of upcoming RSV bronchiolitis epidemics, debate exists whether palivizumab (RSV prophylaxis) should be administered to infants with Congenital Diaphragmatic Hernia (CDH), who may be vulnerable due to lung hypoplasia and pulmonary hypertension.

AIM

To evaluate (1) if CDH infants have higher risk of admission with RSV bronchiolitis than infants in the general population; (2) if palivizumab prophylaxis may reduce this risk.

METHODS

We included all eligible studies examining the risk(s) of RSV-positive bronchiolitis requiring hospital admission in (1) CDH infants without palivizumab prophylaxis versus infants in the general population and (2) CDH infants with prophylaxis versus CDH infants without prophylaxis. The primary outcome evaluated was the risk of admission with RSV bronchiolitis. Data are reported descriptively and meta-analysed when appropriate.

RESULTS

Three eligible retrospective cohort studies were identified: one study found CDH to be an independent risk factor for RSV hospitalisation (odds ratio, 3.30; 95% confidence interval [CI], 2.01-4.4); two studies compared RSV hospitalisation rates in CDH patients who had palivizumab versus those that did not. The pooled risk ratio was 1.11 (95% CI, 0.29-4.23; p = .88). Overall, the quality of evidence was considered poor and one study was industry funded.

CONCLUSION

Whether CDH infants are at particular risk of severe bronchiolitis remains unclear. There is no evidence from this current systematic review that CDH infants should routinely receive palivizumab vaccination prophylaxis.

Risk Factors of Very Severe RSV Infections in a Multicenter Cohort of Very Preterm and Extreme Preterm Babies Receiving or Not Palivizumab

INTRODUCTION

Preterm infants are at risk of lower respiratory tract infections (LRTI), including Respiratory Syncytial Virus (RSV) associated bronchiolitis, for which palivizumab prophylaxis can be proposed. Our aim was to determine risk factors of very severe RSV disease in children born before 34 weeks of gestation.

METHODS

Among 2,101 infants born before 34 weeks of gestation in 3 maternity wards between 2012 and 2017, the laboratory confirmed RSV-infected patients requiring hospitalization before 12 months of corrected age were retrospectively included. We collected data about the neonatal period, the palivizumab prophylaxis and the hospitalization for a RSV-related LRTI. LRTI was considered as very severe (VS-LRTI) when patients required invasive or non-invasive positive pressure ventilation.

RESULTS

Among 86 included patients, 31 met the criteria of VS-LRTI. The VS-LRTI patients had a higher birth gestational age and weight but less heart disease and bronchopulmonary dysplasia. They received palivizumab prophylaxis less frequently than the other patients but the difference was not significant. At the onset of infection, VS-LRTI patients had a younger corrected age for prematurity and presented more frequently with apnea, bradycardia, life-threatening event, hemodynamic failure, hypercapnia. Using logistic regression, the main factor associated with VS-LRTI was a younger corrected age for prematurity at the onset of infection [Odd ratio for each month of corrected age = 0.77 (0.62; 0.93), p = 0.012].

CONCLUSION

Infants at the highest risk of VS-LRTI were infants with a younger corrected age for prematurity. Therefore, a better targeting of infants requiring palivizumab prophylaxis and early interventions at hospital discharge could limit VS-LRTI in these infants.

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

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.

Effect of delayed palivizumab administration on respiratory syncytial virus infection-related hospitalisation: A retrospective, observational study

Respiratory syncytial virus (RSV) infection is an important cause of hospitalization in infants and young children. Monthly administration of palivizumab during the RSV season is effective in preventing severe infections in children with comorbidities. However, determining the onset of the RSV season for starting palivizumab is often challenging. The present study aimed to evaluate the ideal timing to start palivizumab and its effect on hospitalization in the real world.We performed a retrospective, observational study to identify the relationship between the timing of the first dose of palivizumab administration and RSV-related hospitalization. Medical records from 2015 to 2019 were reviewed. We included patients who had indications for palivizumab as of July 1 in each year. We counted the proportion of children receiving palivizumab and the number of RSV infection-related hospitalizations each month. We also evaluated the differences in background and underlying disease between children with and without hospitalization.A total of 498 patients were included, and 105 (21.0%) completed the first dose in July when the RSV season usually begins in Japan. Twenty-three (4.6%) patients were hospitalized for RSV infection during the observation period, with 13 (56.5%) hospitalizations before their first dose of palivizumab. The remaining 10 patients were hospitalized after receiving 1 or more doses of palivizumab. Children living with siblings and children with cyanosis originating from congenital heart disease had a higher risk of RSV with odds ratios of 5.1 (95% confidence interval 1.48-17.6, P < .01) and 3.3 (95% confidence interval 1.33-7.94, P < .01), respectively.Delays in administering palivizumab at the beginning of the season increases the rate of RSV infection-related hospitalization. To maximize prophylactic effectiveness, administering the first dose as early as possible in the RSV season is crucial, with priority for cyanotic children or those with siblings.

Risk factors for recurrent wheezing in preterm infants who received prophylaxis with palivizumab

OBJECTIVE

To determine the prevalence of recurrent wheezing (RW) in preterm infants who received prophylaxis against severe infection with respiratory syncytial virus (RSV) and to identify genetic susceptibility (atopy or asthma) and risk factors for RW.

METHODS

This was a cross-sectional study involving preterm infants who received prophylaxis with palivizumab at a referral center in Brazil during the first two years of age. A structured questionnaire was administered in a face-to-face interview with parents or legal guardians.

RESULTS

The study included 410 preterm infants (median age = 9 months [0-24 months]). In the sample as a whole, 111 children (27.1%; [95% CI, 22.9-31.5]) had RW. The univariate analysis between the groups with and without RW showed no differences regarding the following variables: sex, ethnicity, maternal level of education, gestational age, birth weight, breastfeeding, number of children in the household, day care center attendance, pets in the household, and smoking caregiver. The prevalence of RW was twice as high among children with bronchopulmonary dysplasia (adjusted OR = 2.08; 95% CI, 1.11-3.89; p = 0.022) and almost five times as high among those with a personal/family history of atopy (adjusted OR = 4.96; 95% CI, 2.62-9.39; p < 0.001) as among those without these conditions.

CONCLUSIONS

Preterm infants who received prophylaxis with palivizumab but have a personal/family history of atopy or bronchopulmonary dysplasia are more likely to have RW than do those without these conditions.

Monoclonal Antibodies Against Infectious Microbes: So Long and Too Little!

Monoclonal antibodies (mAbs) as alternatives or more often as complementary to the conventional antimicrobials have been developed for the management of infectious conditions for the past two decades. These pharmacotherapeutic strategies are inevitable as the burden of antimicrobial resistance is far-reaching in recent times. MAbs are part of the targeted pharmacotherapy armamentarium with a high degree of specificity - hence, exert comparatively superior efficacy and tolerability than the conventional polyclonal antisera. So far, only five mAbs have been approved for the management of infectious states, since the marketing authorization (1998) given to palivizumab (Synagis®) for the prophylaxis of lower respiratory tract disease caused by a respiratory syncytial virus in pediatric patients. Ibalizumab-uiyk (Trogarzo™) used for the management of multidrug-resistant HIV-1 infection not yielding to at least 10 antiretroviral drugs, was approved recently. Among the three antibacterial mAbs, raxibacumab (ABthrax®/ Anthrin®) and obiltoxaximab (Anthim®) are indicated for the treatment and prophylaxis of inhalation anthrax due to Bacillus anthracis; bezlotoxumab (Zinplava®) is used to reduce the recurrence of Clostridium difficile infection. There are also around 30 and 15 mAbs in different phases of development for viral and bacterial conditions. As alternatives to the traditional antivirals and antibacterials, the antimicrobial mAbs are the need of the hour. These mAbs are more relevant to the management of conditions like emerging viral outbreaks wherein there is a lack of prophylactic vaccines. The current cutting-edge engineering technologies revolutionizing the production of mAbs include phagedisplayed antibody libraries, cloning from single-memory B cells or single-antibody-secreting plasma B cells, proteomics-directed cloning of mAbs from serum clubbed with high-throughput sequencing techniques. Yet, the cost of manufacture continues to be the main limiting factor. In this review, the different therapeutic monoclonal antibodies directed against the microbial pathogens are discussed.

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

Routine childhood vaccinations are key for the protection of children from a variety of serious and potentially fatal diseases. Current pediatric vaccine schedules mainly cover active vaccines. Active vaccination in infants is a highly effective approach against several infectious diseases; however, thus far, for some important viral pathogens, including respiratory syncytial virus (RSV), vaccine development and license by healthcare authorities have not been accomplished. Nirsevimab is a human-derived, highly potent monoclonal antibody (mAb) with an extended half-life for RSV prophylaxis in all infants. In this manuscript, we consider the potential implications for the introduction of an anti-viral mAb, such as nirsevimab, into the routine pediatric vaccine schedule, as well as considerations for coadministration. Specifically, we present evidence on the general mechanism of action of anti-viral mAbs and experience with palivizumab, the only approved mAb for the prevention of RSV infection in preterm infants, infants with chronic lung disease of prematurity and certain infants with hemodynamically significant heart disease. Palivizumab has been used for over two decades in infants who also receive routine vaccinations without any alerts concerning the safety and efficacy of coadministration. Immunization guidelines (Advisory Committee on Immunization Practices, Joint Committee on Vaccination and Immunization, National Advisory Committee on Immunization, Centers for Disease Control and Prevention, American Academy of Pediatrics, The Association of the Scientific Medical Societies in Germany) support coadministration of palivizumab with routine pediatric vaccines, noting that immunobiologics, such as palivizumab, do not interfere with the immune response to licensed live or inactivated active vaccines. Based on the mechanism of action of the new generation of anti-viral mAbs, such as nirsevimab, which is highly specific targeting viral antigenic sites, it is unlikely that it could interfere with the immune response to other vaccines. Taken together, we anticipate that nirsevimab could be concomitantly administered to infants with routine pediatric vaccines during the same clinic visit.

Unintended Consequences Following the 2014 American Academy of Pediatrics Policy Change for Palivizumab Prophylaxis among Infants Born at Less than 29 Weeks' Gestation

OBJECTIVE

The aim of this study is to compare outpatient respiratory syncytial virus (RSV) immunoprophylaxis (IP) use and relative RSV hospitalization (RSVH) rates for infants <29 weeks' gestational age (wGA) versus term infants before and after the 2014 American Academy of Pediatrics (AAP) policy change.

STUDY DESIGN

Infants were identified in the MarketScan Commercial and Multi-State Medicaid databases. Outpatient RSV IP receipt and relative <29 wGA/term hospitalization risks in 2012 to 2014 and 2014 to 2016 were assessed using rate ratios and a difference-in-difference model.

RESULTS

Outpatient RSV IP receipt by infants <29 wGA and aged <3 months in the Commercial and Medicaid populations and those aged 3 to <6 months in the Medicaid population declined after 2014. Relative RSVH risks for infants <29 wGA were numerically greater after 2014, with infants aged <3 months and Medicaid infants experiencing the greatest increases. Difference-in-difference results indicated a significantly increased relative risk of RSVH for infants <29 wGA versus term (both cohorts aged 0 to <6 months) in the Medicaid-insured population (1.68, p = 0.0054). A nonsignificant increase of similar magnitude occurred in the commercially insured population (1.57, p = 0.2867).

CONCLUSION

The 2014 policy change was associated with a decrease in RSV IP use and an increase in RSVH risk among otherwise healthy infants <29 wGA.

Effectiveness of palivizumab in preventing respiratory syncytial virus infection in high-risk children

To date, there is no consensus regarding palivizumab prophylaxis for respiratory syncytial virus infection. The purpose of this study is to assess the effectiveness of palivizumab prophylaxis to prevent respiratory syncytial virus-related infection consultations and hospitalizations in high-risk children <2 y. We studied children <2 y of age with risk factors who had indication of palivizumab prophylaxis over eight epidemic seasons (2011–2012 to 2018–2019) in Navarra, Spain. Children positives for respiratory syncytial virus by reverse-transcription polymerase chain reaction were compared to negative testers. Palivizumab was indicated in 1,214 children <2 y of age with risk factors during 2011–2012 to 2018–2019 seasons. A total of 142 high-risk children tested for respiratory syncytial virus were included in the study. From the 35 respiratory syncytial virus-positive confirmed cases, 20 (57%) had received palivizumab versus 82 (77%) from the 107 negative controls. The effectiveness of prophylactic palivizumab was 70% (95% CI, 19%-90%) in preventing confirmed clinical infection and 82% (95% CI, 29%-96%) in preventing hospitalized cases. Our results show that palivizumab is notably effective for preventing laboratory-confirmed cases of respiratory syncytial virus and hospitalization in high-risk children <2 y of age. For children who have received palivizumab, the risk of getting sick remains high; thus, other preventive measures are necessary.

Adherence to the 2014 American Academy of Pediatrics palivizumab prophylaxis recommendations

INTRODUCTION

This study aims to describe adherence rates to the 2014 American Academy of Pediatrics (AAP) Committee on Infectious Disease guidance document recommending which patients should receive palivizumab for prophylaxis against respiratory syncytial virus (RSV).

METHODS

A retrospective, single-center analysis of patients who received at least one dose of palivizumab between October 1, 2012, and March 1, 2017 was conducted. Data collected included demographics, medical history, palivizumab administration regimens, and incidence of RSV infection.

RESULTS

Data were collected on 457 patients who received palivizumab over five RSV seasons. Approximately half of the patients (45% and 55%, respectively) received palivizumab according to the AAP recommendations in place at the time (2012 or 2014 recommendations, respectively). One percent of patients had a breakthrough RSV infection after receiving at least one dose of palivizumab. There was no significant difference in the number of breakthrough infections before and after the 2014 recommendations were released (3 vs. 2).

CONCLUSIONS

Approximately half of the patients received prophylaxis in accordance with the 2014 AAP recommendations and infrequently suffered from a breakthrough RSV infection.

Passive Immunoprophylaxis against Respiratory Syncytial Virus in Children: Where Are We Now?

Respiratory syncytial virus (RSV) represents the main cause of acute respiratory tract infections in children worldwide and is the leading cause of hospitalization in infants. RSV infection is a self-limiting condition and does not require antibiotics. However hospitalized infants with clinical bronchiolitis often receive antibiotics for fear of bacteria coinfection, especially when chest radiography is performed due to similar radiographic appearance of infiltrate and atelectasis. This may lead to unnecessary antibiotic prescription, additional cost, and increased risk of development of resistance. Despite the considerable burden of RSV bronchiolitis, to date, only symptomatic treatment is available, and there are no commercially available vaccines. The only licensed passive immunoprophylaxis is palivizumab. The high cost of this monoclonal antibody (mAb) has led to limiting its prescription only for high-risk children: infants with chronic lung disease, congenital heart disease, neuromuscular disorders, immunodeficiencies, and extreme preterm birth. Nevertheless, it has been shown that the majority of hospitalized RSV-infected children do not fully meet the criteria for immune prophylaxis. While waiting for an effective vaccine, passive immune prophylaxis in children is mandatory. There are a growing number of RSV passive immunization candidates under development intended for RSV prevention in all infants. In this review, we describe the state-of-the-art of palivizumab's usage and summarize the clinical and preclinical trials regarding the development of mAbs with a better cost-effectiveness ratio.

Hospitalisations due to respiratory syncytial virus infection in children with Down syndrome before and after palivizumab recommendation in Japan

AIM

Down syndrome has been considered an independent risk factor for respiratory syncytial virus (RSV) infection. Palivizumab, an anti-RSV humanised monoclonal antibody, was currently approved for all children with Down syndrome in Japan. To investigate the change in RSV-associated hospitalisation (RSVH) rates before and after the universal approval of palivizumab in Japan in 2013, we conducted a nationwide retrospective survey.

METHODS

We conducted a nationwide, retrospective, questionnaire survey across paediatric institutions in Japan. The recruited children with Down syndrome were divided into two groups: those born April 2010 to March 2013 (2010-2012 cohort) and those born April 2013 to March 2016 (2013-2015 cohort).

RESULTS

Of the 664 institutions, 321 (48.3%) replied, and a total of 3929 children with Down syndrome were registered. The percentage of children who received palivizumab increased from 49.2% to 82.2%. The cumulative RSVH rate showed a decreased trend in the 2013-2015 cohort (OR, 0.83; 95%CI, 0.63-1.10), while the rate of these children (without CHD and born at a gestational age ≥ 36 weeks) was significantly decreased in the 2013-2015 cohort (OR, 0.56; 95%CI, 0.34-0.92).

CONCLUSION

The cumulative RSVH rate tended to be decreased after approval for all children with Down syndrome although the result was not significant.

Respiratory Syncytial Virus Immunoprophylaxis with Palivizumab: 12-Year Observational Study of Usage and Outcomes in Canada

OBJECTIVE

This study aimed to evaluate palivizumab (PVZ) use, trends in indications, and outcomes of respiratory illness hospitalizations (RIH) and respiratory syncytial virus hospitalizations (RSVH).

STUDY DESIGN

It involves a large, Canadian prospective (2005-2017) observational multicenter study of children at high risk for RSV infection.

RESULTS

A total of 25,003 infants (56.3% male) were enrolled at 32 sites; 109,579 PVZ injections were administered. Indications included: prematurity (63.3%); "miscellaneous" (17.8%); hemodynamically significant congenital heart disease (10.5%); bronchopulmonary dysplasia/chronic lung disease (8.4%). The "miscellaneous" group increased over time (4.4% in 2005-2006 to 22.5% in 2016-2017) and included: trisomy 21, airway anomalies, pulmonary disorders, cystic fibrosis, neurological impairments, immunocompromised, cardiac aged >2 years, multiple conditions, and a residual "unclassified" group. Adherence measured by expected versus actual doses plus correct interdose interval was 64.7%. A total of 2,054 RIH occurred (6.9%); 198 (9.6%) required intubation. Three hundred thirty-seven hospitalized children were RSV-positive (overall RSVH 1.6%). Risk factors for RSVH included having siblings, attending daycare, family history of atopy, smoking exposure, and crowded household. Infants with 5 risk factors were 9.0 times (95% CI or confidence interval 4.4-18.2; p < 0.0005) more likely to have RSVH than infants without risk factors. Three adverse events occurred; none were fatal.

CONCLUSION

Results are relevant to both clinicians and decision-makers. We confirmed the safety of PVZ. Use of PVZ increased steadily for children with miscellaneous conditions and medical complexity. Medical and social factors pose a risk for severe RIH and RSVH with accompanying burden of illness. A vaccine that protects against RSV is urgently required.

KEY POINTS

· Main indications were prematurity (63.3%); "miscellaneous" (17.8%); hemodynamically significant congenital heart disease (10.5%); bronchopulmonary dysplasia/chronic lung disease (8.4%).. · The proportion of children in the "miscellaneous" group, comprised of those with trisomy 21, airway anomalies, pulmonary disorders, cystic fibrosis, neurological impairments, immunocompromised, cardiac aged >2 years, multiple conditions, and a residual "unclassified" group, increased over time (4.4% in 2005-2006 to 22.5% in 2016-2017).. · Respiratory illness-related hospitalization occurred in 2,054 children (6.9%); 198 (9.6%) required intubation. Three hundred thirty-seven hospitalized children were RSV-positive (overall RSVH: 1.6%)..

The Human Nose Organoid Respiratory Virus Model: an Ex Vivo Human Challenge Model To Study Respiratory Syncytial Virus (RSV) and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Pathogenesis and Evaluate Therapeutics

There is an unmet need for preclinical models to understand the pathogenesis of human respiratory viruses and predict responsiveness to immunotherapies. Airway organoids can serve as an ex vivo human airway model to study respiratory viral pathogenesis; however, they rely on invasive techniques to obtain patient samples. Here, we report a noninvasive technique to generate human nose organoids (HNOs) as an alternative to biopsy-derived organoids. We made air-liquid interface (ALI) cultures from HNOs and assessed infection with two major human respiratory viruses, respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infected HNO-ALI cultures recapitulate aspects of RSV and SARS-CoV-2 infection, including viral shedding, ciliary damage, innate immune responses, and mucus hypersecretion. Next, we evaluated the feasibility of the HNO-ALI respiratory virus model system to test the efficacy of palivizumab to prevent RSV infection. Palivizumab was administered in the basolateral compartment (circulation), while viral infection occurred in the apical ciliated cells (airways), simulating the events in infants. In our model, palivizumab effectively prevented RSV infection in a concentration-dependent manner. Thus, the HNO-ALI model can serve as an alternative to lung organoids to study respiratory viruses and test therapeutics. IMPORTANCE Preclinical models that recapitulate aspects of human airway disease are essential for the advancement of novel therapeutics and vaccines. Here, we report a versatile airway organoid model, the human nose organoid (HNO), that recapitulates the complex interactions between the host and virus. HNOs are obtained using noninvasive procedures and show divergent responses to SARS-CoV-2 and RSV infection. SARS-CoV-2 induces severe damage to cilia and the epithelium, no interferon-λ response, and minimal mucus secretion. In striking contrast, RSV induces hypersecretion of mucus and a profound interferon-λ response with ciliary damage. We also demonstrated the usefulness of our ex vivo HNO model of RSV infection to test the efficacy of palivizumab, an FDA-approved monoclonal antibody to prevent severe RSV disease in high-risk infants. Our study reports a breakthrough in both the development of a novel nose organoid model and in our understanding of the host cellular response to RSV and SARS-CoV-2 infection.

Effectiveness of Palivizumab Against Respiratory Syncytial Virus Hospitalization Among Preterm Infants in a Setting With Year-Round Circulation

BACKGROUND

The year-round respiratory syncytial virus (RSV) circulation in tropical regions leads to different transmission patterns and burden of disease among infants born very preterm.

METHODS

We conducted a retrospective cohort study to estimate the effectiveness of palivizumab in preventing RSV hospitalization at 6 and 12 months after discharge, among infants born at <32 weeks' gestation in our tropical setting.

RESULTS

A total of 109 infants (26.3%) received palivizumab at discharge, of 415 who were eligible. All patients received ≥4 doses, with 105 infants (96.3%) completing 5 doses. Within 1 year after discharge, there were 35 RSV-associated admissions (3 [2.8%] in the palivizumab vs 32 [10.5%] in the nonpalivizumab group; P = .02). After adjustment for confounders, the effectiveness of palivizumab against RSV hospitalization was estimated to be 90% (95% confidence interval, 10%-99%) up to 6 months after discharge. The median time to RSV hospitalization was shorter in the nonpalivizumab than in the palivizumab group (median [range], 155 [15-358] vs 287 [145-359] days, respectively; P = .11). Five infants (14.3%), all from the nonpalivizumab group, required admission to the intensive care unit.

CONCLUSIONS

In our setting with year-round RSV circulation, palivizumab prophylaxis was effective in reducing RSV hospitalization among high-risk preterm infants of <32 weeks' gestation within the initial 6 months after discharge.

Feasibility and ethical issues: experiences and concerns of healthcare workers regarding a new RSV prophylaxis programme in Nunavik, Quebec

Background: The respiratory syncytial virus (RSV) is a major cause of hospitalisation in young Inuit children. Prophylaxis with palivizumab is routinely recommended for premature infants and those with severe pulmonary or cardiac diseases. In the fall 2016, the Quebec Ministry of Health expanded the criteria to include healthy full-term (HFT) newborns from Nunavik based on their high RSV hospitalisation rates.

Objectives: The aim of this study was to describe the impact of this programme on Nunavik health services during the first RSV season after its implementation (2016–2017) by studying challenges, concerns and needs of healthcare workers (HCWs).

Methods: An ethnographic approach was used. Semi-structured interviews focusing on HCWs experiences, and opinions to improve the new programme were conducted with 20 HCWs involved in its implementation.

Results: Main reported challenges and concerns were: additional work(over)load, lack of information and evidence about the need and efficacy of palivizumab in HFT newborns, communication issues between stakeholders, and ethical issues regarding the Inuit population.

Conclusion: The study revealed significant feasibility and acceptability issues. The programme was highly resource consuming. To address HCWs’ concerns, evidence-based data regarding palivizumab effectiveness in HFT infants, as well as consultation and involvement of Inuit population are warranted.

Update on respiratory syncytial virus hospitalizations among U.S. preterm and term infants before and after the 2014 American Academy of Pediatrics policy on immunoprophylaxis: 2011-2017

Palivizumab is the only licensed respiratory syncytial virus (RSV) immunoprophylaxis (IP) available to prevent severe RSV disease in high-risk pediatric populations, including infants born at 29-34 weeks' gestational age (wGA). In 2014, the American Academy of Pediatrics (AAP) stopped recommending RSV IP use for otherwise healthy 29-34 wGA infants and stated that 29-34 wGA infants and term infants have similar RSV hospitalization (RSVH) rates. This study aimed to compare RSV IP use and RSVH rates in 29-34 wGA infants and term infants during the 3 RSV seasons before and after the 2014 AAP policy change. RSV IP use in otherwise healthy infants 29-30, 31-32, and 33-34 wGA was estimated from pharmacy or outpatient medical claims for palivizumab. RSVH rates in the first 6 months of life were calculated per 100 infant-seasons. RSVH rate ratios were used to compare preterm infants and term infants before and after the policy change. Across infant cohorts (29-34 wGA) and chronologic age groups (<3 months and 3-<6 months), absolute decreases in RSV IP use between the combined 2011-2014 seasons and 2014-2017 seasons ranged from 7% to 38% and from 68% to 97%, respectively. Compared with 2011-2014, the RSVH risk increased 2.09-fold (P< .001) and 1.76-fold (P< .001) in 2014-2017 for infants born at 29-34 wGA and aged <6 months with commercial and Medicaid insurance, respectively. Overall, RSV IP use declined in the RSV seasons following the 2014 RSV IP policy change, and RSVH increased among 29-34 wGA infants aged <6 months.

Respiratory Syncytial Virus Disease: Immunoprophylaxis Policy Review and Public Health Concerns in Preterm and Young Infants

Globally, respiratory syncytial virus (RSV) is a leading cause of hospitalization due to severe respiratory infections in infants of all gestational ages and children aged 5 years and younger, and it is associated with a substantial health care burden. Approximately, 1% to 3% of infants younger than 1 year are hospitalized with severe RSV disease in the United States. With no specific treatment or vaccine, palivizumab is the only licensed immunoprophylaxis for the prevention of severe RSV disease in high-risk pediatric populations, including infants born at or before 35 weeks’ gestational age (wGA). In the United States, the American Academy of Pediatrics (AAP) periodically publishes its recommendation for the use of RSV immunoprophylaxis, which is largely followed by health care professionals and payers. In 2014, the AAP Committee on Infectious Diseases stopped recommending RSV immunoprophylaxis for otherwise healthy infants born at or after 29 wGA and stated that the RSV hospitalization rates in infants 29 to 34 wGA and full-term infants were similar. Several studies have demonstrated that a significant decline in palivizumab use following the AAP 2014 recommendations was accompanied by increases in rates of RSV hospitalization and disease severity and hospital costs in infants 29 to 34 wGA versus full-term infants. Despite the growing evidence demonstrating high RSV morbidity in infants 29 to 34 wGA, the AAP reaffirmed its 2014 policy in 2019. This article will discuss the critical roles and strategies of advocacy groups and nurses in providing the maximum protection with RSV immunoprophylaxis to all high-risk and label-eligible preterm infants.

Respiratory Syncytial Virus Prophylaxis in Infants With Congenital Diaphragmatic Hernia in the Canadian Respiratory Syncytial Virus Evaluation Study of Palivizumab, 2005-2017

BACKGROUND

Infants with congenital diaphragmatic hernia (CDH) are at an increased risk of respiratory morbidity from recurrent respiratory tract infections including those from respiratory syncytial virus (RSV). Prospective studies on RSV prophylaxis in CDH infants are limited. We determined the risk of respiratory illness- and RSV-related hospitalizations (RIH and RSVH, respectively) among infants prophylaxed for CDH, standard indications (SIs) and those without increased risk (NR).

METHODS

The prospective Canadian Respiratory Syncytial Virus Evaluation Study of Palivizumab (CARESS) registry was searched for infants who received palivizumab during 12 RSV seasons (2005-2017) in Canada. Cox proportional hazards analyses were conducted to compare RIH and RSVH risks across the groups adjusted for potential confounders.

RESULTS

In total, 21 107 infants (201 CDH, 389 NR, and 20 517 SI) were included. RIH incidences were 10.0% (CDH), 2.1% (NR), and 6.2% (SI). CDH patients had a significantly higher RIH hazard compared with NR (hazard ratio [HR], 3.6 [95% confidence interval {CI}, 1.5-8.8]; P = .005) but not SI (HR, 1.2 [95% CI, .8-2.0]; P = .379). RSVH incidences were 0.6%, 0.3%, and 1.5% for CDH, NR, and SI, respectively. RSVH risk was similar across groups (SI: HR, 0.0, P = .922; NR: HR, 0.0, P = .934).

CONCLUSIONS

CDH infants had a 3-fold increased risk of RIH compared to NR but not SI infants. RSVH risk was similar with low RSVH incidences across all groups, implying that CDH infants may benefit from palivizumab during the RSV season, similar to other high-risk groups.

CLINICAL TRIALS REGISTRATION

NCT00420966.

Purification of Antibodies From Human Milk and Infant Digestates for Viral Inhibition Assays

Oral administration of enteric pathogen-specific immunoglobulins may be an ideal approach for preventing infectious diarrhea in infants and children. For oral administration to be effective, antibodies must survive functionally intact within the highly proteolytic digestive tract. As an initial step toward assessing the viability of this approach, we examined the survival of palivizumab, a recombinant monoclonal antibody (IgG1κ), across infant digestion and its ability to neutralize respiratory syncytial virus (RSV). Human milk and infant digestive samples contain substances known to interfere with the RSV neutralization assay (our selected functional test for antibody survival through digestion), therefore, antibody extraction from the matrix was required prior to performing the assay. The efficacy of various approaches for palivizumab purification from human milk, infant's gastric and intestinal digestates, including casein precipitation, salting out, molecular weight cut-off, and affinity chromatography (protein A and G) were compared. Affinity chromatography using protein G with high-salt elution followed by 30-kDa molecular weight cut-off centrifugal filtration was the most effective technique for purifying palivizumab from human milk and infant digestates with a high yield and reduced background interference for the viral neutralization assay. This work is broadly applicable to the optimal isolation of antibodies from human milk and infant digesta for viral neutralization assays, enables the examination of how digestion affects the viral neutralization capacity of antibodies within milk and digestive samples, and paves the way for assessment of the viability of oral administration of recombinant antibodies as a therapeutic approach to prevent enteric pathogen-induced infectious diarrhea in infants.

Pulmonary Deposition of Radionucleotide-Labeled Palivizumab: Proof-of-Concept Study

Objective

Current prevention and/or treatment options for respiratory syncytial virus (RSV) infections are limited as no vaccine is available. Prophylaxis with palivizumab is very expensive and requires multiple intramuscular injections over the RSV season. Here we present proof-of-concept data using nebulized palivizumab delivery as a promising new approach for the prevention or treatment of severe RSV infections, documenting both aerosol characteristics and pulmonary deposition patterns in the lungs of lambs.

Design

Prospective animal study.

Setting

Biosecurity Control Level 2-designated large animal research facility at the Murdoch Children’s Research Institute, Melbourne, Australia.

Subjects

Four weaned Border-Leicester/Suffolk lambs at 5 months of age.

Interventions

Four lambs were administered aerosolized palivizumab conjugated to Tc-99m, under gaseous anesthesia, using either the commercially available AeroNeb Go^® or the investigational HYDRA device, placed in-line with the inspiratory limb of a breathing circuit. Lambs were scanned in a single-photon emission computed tomography (SPECT/CT) scanner in the supine position during the administration procedure.

Measurements and Main Results

Both the HYDRA and AeroNeb Go^® produced palivizumab aerosols in the 1–5 µm range with similar median (geometric standard deviation and range) aerosol droplet diameters for the HYDRA device (1.84 ± 1.40 μm, range = 0.54–5.41μm) and the AeroNeb Go^® (3.07 ± 1.56 μm, range = 0.86–10 μm). Aerosolized palivizumab was delivered to the lungs at 88.79–94.13% of the total aerosolized amount for all lambs, with a small proportion localized to either the trachea or stomach. No difference between devices were found. Pulmonary deposition ranged from 6.57 to 9.25% of the total dose of palivizumab loaded in the devices, mostly in the central right lung.

Conclusions

Aerosolized palivizumab deposition patterns were similar in all lambs, suggesting a promising approach in the control of severe RSV lung infections.

Partial Degradation of Recombinant Antibody Functional Activity During Infant Gastrointestinal Digestion: Implications for Oral Antibody Supplementation

Oral administration of engineered immunoglobulins has the potential to prevent enteric pathogen-induced diarrhea in infants. To prevent infection, these antibodies need to survive functionally intact in the proteolytic environment of the gastrointestinal tract. This research examined both ex vivo and in vivo the functional survival across infant digestion of palivizumab, a model FDA-approved recombinant antibody against respiratory syncytial virus (RSV) F protein. Palivizumab-fortified feed (formula or human milk), infant gastric, and intestinal samples were incubated to simulate in vivo digestion (ex vivo digestion). Palivizumab-fortified human milk was also fed to infants, followed by collection of gastric and intestinal samples (in vivo digestion). Palivizumab was purified from the samples of digestate using protein G spin columns followed by filtration through molecular weight cut-off membranes (30 kDa). Palivizumab functional survival across ex vivo and in vivo digestion was determined via an anti-idiotype ELISA and an RSV plaque reduction neutralization test. Palivizumab concentration and RSV neutralization capacity both decreased when incubated in intestinal samples (ex vivo study). The concentration and neutralization activity of orally-supplemented palivizumab also decreased across infant digestion (in vivo study). These results indicate that if recombinant IgGs were selected for oral supplementation to prevent enteric infections, appropriate dosing would need to account for degradation occurring in the digestive system. Other antibody formats, structural changes, or encapsulation could enhance survival in the infant gastrointestinal tract.

Cost-analysis of Withdrawing Immunoprophylaxis for Respiratory Syncytial Virus in Infants Born at 33-35 Weeks Gestational Age in Quebec: A Multicenter Retrospective Study

BACKGROUND

In 2015, the Quebec Ministry of Health limited palivizumab prophylaxis for respiratory syncytial virus (RSV) in premature infants to those born at <33 weeks gestational age (wGA), unless other indications were present. We compared RSV-related costs for 2 seasons before the change (2013-2014, 2014-2015) and 2 seasons after (2015-2016, 2016-2017) in premature infants 33-35 wGA.

METHODS

Using payer and societal perspectives, costs associated with hospitalizations for RSV and lower respiratory tract infection (LRTI) in infants born at 33-35 wGA were estimated. Inputs were from a 2013-2017 retrospective cohort study in 25 Quebec hospitals of RSV/LRTI hospitalizations among infants <6 months old at the start of, or born during, the RSV season. Resource utilization data (hospital stay, procedures, visits, transportation, out-of-pocket expenses and work productivity) were collected from charts and parent interviews allowing estimation of direct and indirect costs. Costs, including palivizumab administration, were derived from provincial sources and adjusted to 2018 Canadian dollars. Costs were modeled for preterm infants hospitalized for RSV/LRTI pre- and postrevision of guidelines and with matched term infants hospitalized for RSV/LRTI during 2015-2017 (comparator).

RESULTS

Average total direct and indirect costs for 33-35 wGA infants were higher postrevision of guidelines ($29,208/patient, 2015-2017; n = 130) compared with prerevision ($16,976/patient, 2013-2015; n = 105). Total costs were higher in preterm infants compared with term infants (n = 234) postrevision of guidelines ($29,208/patient vs. $10,291/patient).

CONCLUSIONS

Immunoprophylaxis for RSV in infants born at 33-35 wGA held a cost advantage for hospitalizations due to RSV/LRTI.