Respiratory syncytial virus prophylaxis in infants with congenital airway anomalies compared to standard indications and complex medical disorders

Effectiveness and Safety of Palivizumab for the Prevention of Serious Lower Respiratory Tract Infection Caused by Respiratory Syncytial Virus: A Systematic Review

OBJECTIVE

 Palivizumab is a humanized monoclonal antibody approved for the prevention of serious lower respiratory tract infection (LRTI) caused by respiratory syncytial virus (RSV) in infants and young children at high risk of RSV disease. This systematic review summarized evidence on the effectiveness and safety of palivizumab when used in approved populations.

STUDY DESIGN

 A systematic review of Phase III trials and observational studies was conducted according to the population, intervention, comparator, outcome, timing, setting (PICOTS) approach (PROSPERO, CRD42021281380). Target populations consisted of infants with a history of premature birth (≤35-week gestational age) and children aged <2 years with bronchopulmonary dysplasia (BPD) or with hemodynamically significant congenital heart disease (hs-CHD). Outcomes of interest included RSV-related hospitalization, admission to intensive care unit (ICU), requirement for mechanical ventilation, treatment-related adverse events (AEs), and RSV-related deaths. Information sources were literature search (Ovid MEDLINE and Embase), pragmatic searches, and snowballing (covering the period up to 07 September 2021).

RESULTS

 A total of 60 sources were included (5 Phase III trials and 55 observational studies). RSV-related hospitalization rates following palivizumab prophylaxis in Phase III trials were 1.8% in premature infants and 7.9% in children with BPD, which were significantly lower than rates in placebo arms. In the real-world setting, similar hospitalization rates were found (0.7-4.0% in premature infants [16 studies] and 0-5.5% in patients with BPD [10 studies]) with ICU admission reported in 0 to 33.3% of patients hospitalized for RSV. In Phase III trials, RSV-related mortality rates were 0.2 and 0.3%, while AEs occurred in 11% of premature and/or BPD patients and 7.2% of hs-CHD patients, consisting mainly of injection site reaction, fever, and diarrhea. Similar results were found in observational studies.

CONCLUSION

 This systematic review supports the effectiveness and safety of palivizumab in the indicated populations.

KEY POINTS

· Systematic review supports the positive benefit-risk profile of palivizumab in the indicated populations.. · Real-world safety and effectiveness of palivizumab are consistent with Phase III trials results.. · Palivizumab reduces RSV-related hospitalizations, ICU admissions, and need for mechanical ventilation..

Risk factors for respiratory syncytial virus bronchiolitis hospitalizations in children with chronic diseases

BACKGROUND

Respiratory syncytial virus (RSV) bronchiolitis is the most common lower respiratory tract disorder causing hospitalization in infants. Due to decreased hospitalization rates of premature infants following Palivizumab immune prophylaxis, the proportion of infants with chronic diseases not eligible for Palivizumab has increased.

AIM

To characterize infants hospitalized during 2014-2018 with RSV bronchiolitis, to compare between those with and without chronic conditions, and to identify risk factors for severe disease.

METHODS

This retrospective study analyzed demographic and clinical data of patients younger than 2 years admitted with bronchiolitis during four consecutive RSV seasons.

RESULTS

Of 1124 hospitalizations due to RSV bronchiolitis, 244 (22%) were in infants with chronic diseases. Although 20/1124 qualified for RSV prophylaxis, only eight received immune prophylaxis. Compared to otherwise healthy infants, children with chronic diseases had longer hospitalizations, median 4.8 days (interquartile range [IQR]: 3.4-8.3) versus 3.7 days (IQR: 2.7-5.1), p < .001; and higher pediatric intensive care unit (PICU) and readmission rates (9% vs. 4.5%, p = .007% and 3% vs. 1%, p = .055, respectively). Children with Down's syndrome comprised 2% of all hospitalizations, but 8% of PICU admissions; their median length of hospitalization was 10.7 days (IQR: 6.6-17.6). Respiratory tract malformations were present in 2% of hospitalizations, and comprised 4% of PICU admissions.

CONCLUSION

Among infants admitted with RSV bronchiolitis, those with chronic diseases had longer hospitalizations and higher rates of transfer to the PICU. Children with multiple comorbidities, and especially those with Down's syndrome, are at particularly high risk for severe hospitalization and may benefit from RSV immune prophylaxis.

Reappraisal of the Subtropical Guidelines on Palivizumab Prophylaxis in Congenital Heart Disease

Objective: To define the impact of associated abnormalities on the efficacy of the novel subtropical guidelines for palivizumab prophylaxis on respiratory syncytial virus (RSV)-related hospitalizations in patients with hemodynamically significant congenital heart disease (hsCHD). Method: This prospective study enrolled every patient seen at a tertiary care center for hsCHD, who was born between 2014 and 2018 and received at least 1 dose of palivizumab, according to the subtropical guidelines. The patients were followed until the age of 2 years. Results: A total of 772 patients (49% male) were enrolled. Cyanotic CHD was seen in 46% of patients, of whom 23% had associated abnormalities. Lung/airway abnormalities (14%) were the most common followed by the genetic syndromes associated with CHD (7.3%). Among the 772 patients, RSV-related hospitalizations occurred in 3.2 and 2.2% children aged ≤ 12 and 13-24 months, respectively. Most of the RSV infections occurred in patients no longer satisfying the criteria for palivizumab prophylaxis. The patients with associated abnormalities but not the type of CHD, patient age, and patient sex were risk factors for RSV-related hospitalizations. The rates of RSV-related hospitalizations, admission to the intensive care unit, and endotracheal intubation were higher for patients with associated anomalies than for other patients before 24 months of age (10.2 vs. 4.0%, 67 vs. 33%, and 39 vs. 4.2%, p = 0.004, 0.06, 0.013, respectively). Conclusion: Children with abnormalities, especially genetic syndromes and lung/airway problems associated with CHD, are at high risk for RSV-related hospitalization. Our current subtropical guidelines for palivizumab prophylaxis in patients with hsCHD, should be revised to include the results of this study.

Congenital malformations potentially affecting respiratory function: multidisciplinary approach and follow-up

Background and aim.

Congenital malformations such as oesophageal atresia (OA) and tracheoesophageal fistula (TOF), congenital pulmonary airway malformations (CPAMs), congenital diaphragmatic hernia (CDH) and vascular rings (VRs) can affect lung development and respiratory function. This observational study describes our multidisciplinary approach and respiratory follow-up of children with such congenital malformations.

Methods.

Clinical data of children followed at the Pediatric Respiratory Unit of Parma University Hospital (Italy) between January 2015 and January 2020 were collected.

Results.

Twenty-three patients with congenital malformation affecting lung development were identified. Almost half of our patients were diagnosed with fetal ultrasound. Children attended the clinic at a mean age of 3 (3.7) years and follow-up visits were scheduled every 6 months average. More than half of our patients were hospitalized for lower respiratory tract infections. Six out of 9 children able to perform spirometry showed anomalies in lung function. Chest physiotherapy was recommended especially in children with OA.

Conclusions.

Children with congenital malformations affecting lung development are at risk of short and long-term respiratory complications, especially in the first years of life. OA was the malformation more associated to respiratory problems. Multidisciplinary approach and appropriate personalized follow-up are recommended for the best management of these children. (www.actabiomedica.it)

Prevalence and clinical characteristics of perinatal chronic lung disease by infant gestational age

BACKGROUND:

Children with perinatal chronic lung disease (CLD) are at elevated risk for severe respiratory syncytial virus (RSV) disease in the first two years of life. The American Academy of Pediatrics policy does not recommend RSV immunoprophylaxis for infants with CLD born at ≥32 weeks’ gestational age (wGA). The objective of this study was to describe the number and clinical characteristics of US infants in this population.

METHODS:

Birth hospitalization data from the Kids’ Inpatient Database were utilized to estimate the prevalence of CLD (International Classification of Diseases, Ninth Revision [ICD-9] = 770.7) in 2003-2012 overall and by gestational age (ICD-9 = 765.21–765.29). CLD birth hospitalizations were evaluated by length of stay, costs, ventilatory support, and inpatient mortality.

RESULTS:

A total of 33,537 infants were diagnosed with CLD, representing 0.2% of US births; 79% had wGA coded in the database. Among infants with CLD with wGA, 3.5% were born at >32 wGA, representing 7 of every 100,000 US births, or approximately 300 infants annually. Across all wGA categories, birth hospitalization length of stay and costs were elevated, and mechanical ventilation use ranged from 73% to 97%. All-cause inpatient mortality was highest among those <27 wGA and >32 wGA.

CONCLUSIONS:

Approximately 300 infants born at >32 wGA are diagnosed with CLD annually in the United States. The all-cause perinatal mortality rate is high in this population. The rationale for excluding this small but high-risk group of infants from the recommendations for RSV immunoprophylaxis is unclear.

Conceptual Approaches to Modulating Antibody Effector Functions and Circulation Half-Life

Antibodies and Fc-fusion antibody-like proteins have become successful biologics developed for cancer treatment, passive immunity against infection, addiction, and autoimmune diseases. In general these biopharmaceuticals can be used for blocking protein:protein interactions, crosslinking host receptors to induce signaling, recruiting effector cells to targets, and fixing complement. With the vast capability of antibodies to affect infectious and genetic diseases much effort has been placed on improving and tailoring antibodies for specific functions. While antibody:antigen engagement is critical for an efficacious antibody biologic, equally as important are the hinge and constant domains of the heavy chain. It is the hinge and constant domains of the antibody that engage host receptors or complement protein to mediate a myriad of effector functions and regulate antibody circulation. Molecular and structural studies have provided insight into how the hinge and constant domains from antibodies across different species, isotypes, subclasses, and alleles are recognized by host cell receptors and complement protein C1q. The molecular details of these interactions have led to manipulation of the sequences and glycosylation of hinge and constant domains to enhance or reduce antibody effector functions and circulating half-life. This review will describe the concepts being applied to optimize the hinge and crystallizable fragment of antibodies, and it will detail how these interactions can be tuned up or down to mediate a biological function that confers a desired disease outcome.