Respiratory Syncytial Virus Hospitalizations in Healthy Preterm Infants: Systematic Review

Maternal Risk Factors for Respiratory Syncytial Virus Lower Respiratory Tract Infection in Otherwise Healthy Preterm and Term Infants: A Systematic Review and Meta-analysis

BACKGROUND/OBJECTIVE

To date, there is no published, formal assessment of all maternal risk factors for respiratory syncytial virus lower respiratory tract infection (RSV-LRTI) in infants. A systematic literature review and meta-analysis were undertaken to ascertain: What maternal risk factors are associated with an increased risk of RSV-LRTI in infants?

METHODS

The systematic literature review used explicit methods to identify, select and analyze relevant data. PubMed, Embase and the Cochrane Library were searched (November 2022) using terms regarding: (1) RSV/LRTI; (2) risk factors; (3) pregnant/postpartum population. Bayesian meta-analysis compared RSV hospitalization (RSVH) risk in infants born to mothers with or without certain risk factors.

RESULTS

A total of 2353 citations were assessed and 20 were included in the final review (10 individual studies; 10 pooled analyses). In 10 studies examining infants (<1 year) without comorbidities (primary outcome), 10 maternal risk factors were associated with RSV-LRTI/RSVH in multivariate analyses. Meta-analysis revealed smoking while pregnant increased infant RSVH risk by 2.01 (95% credible interval: 1.52-2.64) times, while breast-feeding was protective (0.73, 95% credible interval: 0.58-0.90). Risk scoring tools have reported that maternal risk factors contribute between 9% and 21% of an infant's total risk score for RSVH.

CONCLUSIONS

A greater understanding of maternal risk factors and their relative contribution to infant RSV-LRTI will enable more accurate assessments of the impact of preventive strategies.

Comparison of a static cohort model and dynamic transmission model for respiratory syncytial virus intervention programs for infants in England and Wales

BACKGROUND

A recent study comparing results of multiple cost-effectiveness analyses (CEAs) in a hypothetical population found that monoclonal antibody (mAb) immunoprophylaxis for respiratory syncytial virus (RSV) in infants averted fewer medically attended cases when estimated using dynamic transmission models (DTMs) versus static cohort models (SCMs). We aimed to investigate whether model calibration or parameterization could be the primary driver of inconsistencies between SCM and DTM predictions.

METHODS

A recently published DTM evaluating the CEA of infant mAb immunoprophylaxis in England and Wales (EW) was selected as the reference model. We adapted our previously published SCM for US infants to EW by utilizing the same data sources used by the DTM. Both models parameterized mAb efficacy from a randomized clinical trial (RCT) that estimated an average efficacy of 74.5% against all medically attended RSV episodes and 62.1% against RSV hospitalizations. To align model assumptions, we modified the SCM to incorporate waning efficacy. Since the estimated indirect effects from the DTM were small (i.e., approximately 100-fold smaller in magnitude than direct effects), we hypothesized that alignment of model parameters should result in alignment of model predictions. Outputs for model comparison comprised averted hospitalizations and averted GP visits, estimated for seasonal (S) and seasonal-with-catchup (SC) immunization strategies.

RESULTS

When we aligned the SCM intervention parameters to DTM intervention parameters, significantly more averted hospitalizations were predicted by the SCM (S: 32.3%; SC: 51.3%) than the DTM (S: 17.8%; SC: 28.6%). The SCM most closely replicated the DTM results when the initial efficacy of the mAb intervention was 62.1%, leading to an average efficacy of 39.3%. Under this parameterization the SCM predicted 17.4% (S) and 27.7% (SC) averted hospitalizations. Results were similar for averted GP visits.

CONCLUSIONS

Parameterization of the RSV mAb intervention efficacy is a plausible primary driver of differences between SCM versus DTM model predictions.

Enabling methanol fixation of pediatric nasal wash during respiratory illness for single cell sequencing in comparison with fresh samples

BACKGROUND

Lower respiratory tract infection (LRTI) including pneumonia, bronchitis, and bronchiolitis is the sixth leading cause of mortality around the world and leading cause of death in children under 5 years. Systemic immune response to viral infection is well characterized. However, there is little data regarding the immune response at the upper respiratory tract mucosa. The upper respiratory mucosa is the site of viral entry, initial replication and the first barrier against respiratory infections. Lower respiratory tract samples can be challenging to obtain and require more invasive procedures. However, nasal wash (NW) samples from the upper respiratory tract can be obtained with minimal discomfort to the patient.

METHOD

In a pilot study, we developed a protocol using NW samples obtained from hospitalized children with LRTI that enables single cell RNA sequencing (scRNA-seq) after the NW sample is methanol-fixed.

RESULTS

We found no significant changes in scRNA-seq qualitative and quantitative parameters between methanol-fixed and fresh NW samples.

CONCLUSIONS

We present a novel protocol to enable scRNA-seq in NW samples from children admitted with LRTI. With the inherent challenges associated with clinical samples, the protocol described allows for processing flexibility as well as multicenter collaboration.

IMPACT

There are no significant differences in scRNA-seq qualitative and quantitative parameters between methanol fixed and fresh Pediatric Nasal wash samples. The study demonstrates the effectiveness of methanol fixation process on preserving respiratory samples for single cell sequencing. This enables Pediatric Nasal wash specimen for single cell RNA sequencing in pediatric patients with respiratory tract infection and allows processing flexibility and multicenter collaboration.

Effect of Palivizumab Prophylaxis on Respiratory Syncytial Virus Infection in Very Preterm Infants in the First Year of Life in The Netherlands

Respiratory Syncytial Virus (RSV) poses a severe threat to infants, particularly preterm infants. Palivizumab, the standard preventive prophylaxis, is primarily utilized in high-risk newborns due to its cost. This study assessed palivizumab's effectiveness in preventing RSV infections in predominantly very preterm infants during their first year of life. Serum samples from a prospective multicentre cohort study in the Netherlands were analyzed to assess RSV infection rates by measuring IgG levels against three RSV proteins: nucleoprotein, pre-fusion, and post-fusion protein. Infants were stratified based on gestational age (GA), distinguishing very preterm (≤32 weeks GA) from moderate/late preterm (>32 to ≤36 weeks GA). In very preterm infants, palivizumab prophylaxis significantly reduced infection rates (18.9% vs. 48.3% in the prophylaxis vs. non-prophylaxis group. Accounting for GA, sex, birth season, and birth weight, the prophylaxis group showed significantly lower infection odds. In infants with >32 to ≤36 weeks GA, the non-prophylaxis group (55.4%) showed infection rates similar to the non-prophylaxis ≤32-week GA group, despite higher maternal antibody levels in the moderate/late preterm infants. In conclusion, palivizumab prophylaxis significantly reduces RSV infection rates in very premature infants. Future research should explore clinical implications and reasons for non-compliance, and compare palivizumab with emerging prophylactics like nirsevimab aiming to optimize RSV prophylaxis and improve preterm infant outcomes.

Clinical and economic hospital burden of acute respiratory infection (BARI) due to respiratory syncytial virus in Spanish children, 2015-2018

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory infection (ALRI) in children, causing frequent outpatient visits and hospitalizations. Our study aimed to describe the clinical and direct economic burden of ALRI hospitalizations related to RSV in children in Spain and the characteristics of patients and their episodes. In this retrospective study, ALRI hospitalizations in children aged < 5 years for 2015-2018 were reviewed using anonymized administrative public hospital discharge data from Spain. Three case definitions were considered: (a) RSV-specific; (b) RSV-specific and unspecified acute bronchiolitis (RSV-specific and bronchiolitis); and (c) RSV-specific and unspecified ALRI (RSV-specific and ALRI). The study reported a mean of 36,743 yearly admissions potentially due to RSV, resulting in a mean annual cost of €87.1 million. RSV-specific codes accounted for 39.2% of cases, unspecified acute bronchiolitis for 20.1%, and other unspecified ALRI codes for the remaining 40.6%. The mean hospitalization rate per 1,000 children was 55.5 in the first year of life, 16.0 in the second, and 5.4 between 24 and 59 months. A considerable proportion of cases occurred in children under two years old (> 80.4%) and even during the first year of life (> 61.7%). Otherwise healthy children accounted for 92.9% of hospitalizations and 83.3% of costs during the period. Children born preterm accounted for 1.3% of hospitalizations and 5.7% of costs. The findings revealed that RSV still contributes to a high burden on the Spanish health care system. Children under one year of age and otherwise healthy term infants accounted for most of the substantial clinical and economic burden of RSV. Current evidence potentially underestimates the true epidemiology and burden of severe RSV infection; thus, further studies focusing on the outpatient setting are needed.

The Role of Work as a Social Determinant of Health in Mother's Own Milk Feeding Decisions for Preterm Infants: A State of the Science Review

In the United States, 10% of infants are born preterm (PT; <37 weeks gestational age) each year and are at higher risk of complications compared to full term infants. The burden of PT birth is borne disproportionately by Black versus non-Black families, with Black mothers significantly more likely to give birth to a PT infant. One proven strategy to improve short- and long-term health outcomes in PT infants is to feed mother's own milk (MOM; breast milk from the mother). However, mothers must make decisions about work and MOM provision following PT birth, and more time spent in paid work may reduce time spent in unpaid activities, including MOM provision. Non-Black PT infants are substantially more likely than Black PT infants to receive MOM during the birth hospitalization, and this disparity is likely to be influenced by the complex decisions mothers of PT infants make about allocating their time between paid and unpaid work. Work is a social determinant of health that provides a source of income and health insurance coverage, and at the same time, has been shown to create disparities through poorer job quality, lower earnings, and more precarious employment in racial and ethnic minority populations. However, little is known about the relationship between work and disparities in MOM provision by mothers of PT infants. This State of the Science review synthesizes the literature on paid and unpaid work and MOM provision, including: (1) the complex decisions that mothers of PT infants make about returning to work, (2) racial and ethnic disparities in paid and unpaid workloads of mothers, and (3) the relationship between components of job quality and duration of MOM provision. Important gaps in the literature and opportunities for future research are summarized, including the generalizability of findings to other countries.

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

Infections with respiratory syncytial virus (RSV) can cause severe disease. In young children, RSV is the most common cause of lower respiratory tract illness and life-threatening infections most commonly occur in the first years of life. In adults, elderly and immunocompromised people are most vulnerable. Recently there has been an acceleration in the development of candidate RSV vaccines, monoclonal antibodies and therapeutics which are expected to become available in Europe within the next 2-10 years. Understanding the true burden of childhood RSV disease will become very important to support public health authorities and policy makers in the assessment of new therapeutic opportunities against RSV disease. A systematic literature search was performed to map local data on the burden of RSV disease and to evaluate available RSV surveillance systems. A group of 9 paediatric infectious diseases specialists participated in an expert panel. The purpose of this meeting was to evaluate and map the burden associated with RSV infection in children, including patient pathways and the epidemiological patterns of virus circulation in Belgium. Sources of information on the burden of RSV disease in Belgium are very limited. For the outpatient setting, it is estimated that 5-10% of young patients seen in primary care are referred to the hospital. Around 3500 children between 0 and 12 months of age are hospitalized for RSV-bronchiolitis every year and represent the majority of all hospitalizations. The current Belgian RSV surveillance system was evaluated and found to be insufficient. Knowledge gaps are highlighted and future perspectives and priorities offered.

CONCLUSION

The Belgian population-based RSV surveillance should be improved, and a hospital-led reporting system should be put in place to enable the evaluation of the true burden of RSV disease in Belgium and to improve disease management in the future.

WHAT IS KNOWN

• RSV bronchiolitis is a very important cause of infant hospitalization. • The burden of disease in the community is poorly studied and underestimated.

WHAT IS NEW

• This expert opinion summarizes knowledge gaps and offers insights that allow improvement of local surveillance systems in order to establish a future-proof RSV surveillance system.

The clinical impact of multiple prevention strategies for respiratory syncytial virus infections in infants and high-risk toddlers in the United States

BACKGROUND

Respiratory syncytial virus (RSV) remains a leading cause of medically-attended acute respiratory infection in infants and children. With multiple preventative interventions under development, accurate estimates of health care resource utilization are essential for policy decision making.

METHODS

We developed a literature-based decision-tree model that estimated annual medically-attended RSV (MA-RSV) lower respiratory tract infection (LRTI) and non-LRTI episodes in the US for all infants and for high-risk toddlers. The model accounted for the gestational age and birth-month of infants, and the seasonal variation in RSV incidence. The impact of no prophylaxis, palivizumab, maternal vaccine, and long-acting monoclonal antibody (mAb) interventions was estimated.

RESULTS

We estimated 1.23 million (range: 0.96 million-1.40 million) annual MA-RSV LRTI/non-LRTI episodes comprised of 1.19 million (range: 0.93 million-1.36 million) emergency department (ED) and outpatient visits, and 39,040 (range: 32,726-45,851) hospitalizations. Outpatient and ED visits were comprised of 586,034 (range: 430,595-718,868) LRTIs and 608,733 (range: 495,705-644,658) non-LRTIs. The long-acting mAb intervention resulted in the greatest number of averted outpatient and ED episodes (310,997 [53%] LRTIs; 284,305 [47%] non-LRTIs) and hospitalizations (21,845 [56%]). Full-term infants constitute the highest proportion of episodes across all interventions.

CONCLUSIONS

MA-RSV disease is substantial in infants and high-risk toddlers. Long-acting mAbs are most effective at reducing the number of MA-RSV LRTI/non-LRTI episodes, and the only intervention that prevents disease in older infants (≥6 months old).

Bronchiolitis therapies and misadventures

Viral bronchiolitis, which is most commonly caused by an infection with the respiratory syncytial virus (RSV), can lead to respiratory difficulties in young children which may require hospitalization. Despite years of research and medical trials, the mainstay of bronchiolitis treatment remains supportive only. This review provides an overview of the history of different treatments for bronchiolitis, including those that failed, as well as new therapies that are under study. Future studies for the treatment of bronchiolitis should consider different age-groups, important subgroups (i.e., those with a prior history of wheezing, those with a family history of asthma and those with non-RSV viral etiologies) whose response to treatment may differ from that of the composite group.

Evaluation of respiratory complications in a cohort of preterm infants who did not receive palivizumab monoclonal antibodies

ABSTRACT Objectives: to analyze the occurrence of respiratory complications over the first year of life in preterm infants who did not receive palivizumab monoclonal antibodies. Methods: analytical retrospective cohort study with preterm infants born between 2012 and 2016 in Uberlândia, state of Minas Gerais, Brazil. Data collection occurred from January to November 2018, by consulting hospital and primary healthcare medical records. Data were processed with the Poisson regression model, with p<0.05. Results: of a total of 5,213 preterm births, 504 (9.7%) met the inclusion criteria. The preterm infants in this subset were assisted 2,899 times in primary care, which resulted in 1,098 (37.5%) medical diagnoses, of which 803 (78.5%) involved the respiratory tract. Preterm babies fed on formula milk at hospital discharge had more diagnoses of respiratory diseases. Maternal age (p=0.039), respiratory diagnosis at hospital discharge (p=0.028), and number of sporadic appointments (p<0.001) showed a significant association with bronchiolitis; number of sporadic appointments showed a significant association with occurrence of respiratory diseases; and breastfeeding had a protective effect against the development of bronchiolitis. Conclusions: preterm infants who did not receive palivizumab showed a high percentage of respiratory diseases, and breastfeeding helped protect them against bronchiolitis. It is recommended that these preterm babies be monitored in primary health care.

Role of age and birth month in infants hospitalized with RSV-confirmed disease in the Valencia Region, Spain

Background

RSV is the leading cause of hospital admissions in infants and the principal cause of bronchiolitis in young children. There is a lack of granular data on RSV‐associated hospitalization per season using laboratory confirmed results. Our current study addresses this issue and intends to fill this gap.

Methods

The study was conducted from 2014 through 2018, in 4 to 10 hospitals in the Valencia Region, Spain. Infants included in this study were admitted in hospital through the Emergency Department with a respiratory complaint and tested by RT‐PCR for RSV in a central laboratory.

Results

Incidence rates of RSV‐associated hospitalization varied by season and hospital. Overall, the highest incidence rates were observed in 2017/2018. RSV‐associated hospitalization was highest in infants below 3 months of age and in those born before or at the beginning of the RSV season. Almost 54% of total infants hospitalized with laboratory confirmed RSV were found to be born outside the season, from April to October. The RSV positivity rate by ICD‐10 discharged codes varied by season and age with results from 48% to 57% among LRI (J09‐J22).

Conclusion

The study was instrumental in bringing forth the time unpredictability of RSV epidemics, the critical impact of age, and the comparable distribution of RSV‐associated hospitalization in infants born on either side of the RSV season. These data could help in better characterization of the population that drives the healthcare burden and is crucial for the development of future immunization strategies, especially with upcoming vaccines in against RSV.

Influenza hospitalizations during childhood in children born preterm

Objective

The objective is to determine if children born preterm were at increased risk of influenza hospitalization up to age five.

Methods

National registry data on all children born in Norway between 2008 and 2011 were used in Cox regression models to estimate adjusted hazard ratios (aHRs) for influenza hospitalizations up to age five in children born preterm (<37 pregnancy weeks). HRs were also estimated separately for very preterm (<32 weeks), early term (37–38 weeks), and post‐term (≥42 weeks) children.

Results

Among 238,628 children born in Norway from January 2008 to December 2011, 15,086 (6.3%) were born preterm. There were 754 (0.3%) children hospitalized with influenza before age five. The rate of hospitalizations in children born preterm was 13.8 per 10,000 person‐years (95% confidence interval [CI] [11.3, 16.7]), and 5.9 per 10,000 person‐years (95% CI [5.5, 6.4]) in children born at term (≥37 weeks). Children born preterm had a higher risk of influenza hospitalization before age 5: aHR 2.33 (95% CI [1.85, 2.93]). The risk increased with decreasing gestational age and was highest among those born extremely/very preterm; aHR 4.07 (95% CI [2.63, 6.31]). Compared with children born at 40–41 weeks, children born early term also had an elevated risk of influenza hospitalization; aHR (37 weeks) 1.89 (95% CI [1.43, 2.50]), aHR (38 weeks) 1.43 (95% CI [1.15, 1.78]).

Conclusion

Children born preterm had a higher risk of influenza hospitalizations before age five. An elevated risk was also present among children born at an early term. Children born preterm could benefit from influenza vaccinations.

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.

Long-term Assessment of Healthcare Utilization 5 Years After Respiratory Syncytial Virus Infection in US Infants

BACKGROUND

Respiratory syncytial virus (RSV) is the primary cause of respiratory tract infections in infants; however, current burden estimates report only the short-term effects of acute infection.

METHODS

Infants with RSV infection and ≥24 months of continuous enrollment were retrospectively identified from the Truven MarketScan database (1 January 2004-30 September 2015). Exposed infants (n = 38 473) were propensity score matched to nonexposed controls (n = 76 825) by baseline characteristics and gestational age. Five-year cumulative all-cause, asthma/wheezing, and respiratory event-related hospitalization rates and physician and emergency department healthcare-resource utilization rates were assessed.

RESULTS

During follow-up, RSV-infected cohorts had higher average all-cause cumulative hospitalization rates, compared with controls, with values of 79.9 hospitalizations/100 patient-years (95% confidence interval [CI], 41.7-118.2) for 213 early premature infants (P < .001), 18.2 hospitalizations/100 patient-years (95% CI, .8-35.7) for 397 premature infants (P = .04), 34.2 hospitalizations/100 patient-years (95% CI, 29.1-39.2) for 4446 late premature infants (P < .001), and 16.1 hospitalizations/100 patient-years (95% CI, 14.9-17.4) for 33 417 full-term infants (P < .001). Cumulative rates of physician and emergency department visits were also higher for RSV-infected infants. Asthma/wheezing accounted for 10%-18% of total 5-year physician visits.

CONCLUSIONS

Infant RSV infection has a significant long-term healthcare-resource utilization impact across gestational ages for at least 5 years after infection, most of it in the first 2 years. Systematically collecting healthcare-resource utilization data will be important for cost-effectiveness evaluations of RSV interventions in planned or ongoing trials.

Hospitalizations for viral respiratory infections in children under 2 years of age: epidemiology and in-hospital complications

BACKGROUND

Viral respiratory infections (VRIs) are a frequent cause of hospitalization in children under 24 months of age. A history of prematurity or heart disease may be a risk factor for complications in patients hospitalized for VRI. The objective was to describe epidemiological data for children hospitalized for IRV and aged 1 to 24 months and to identify risk factors for the presence of in-hospital complications and mortality over a period of 5 years.

METHODS

This was a cross-sectional study. Patients registered with VRI codes B974, J12, J120-J129X, J168, J17, J171, J178, J20, J203-J209, J21, J210, J211, J218, J219 (based on International Classification of Diseases [ICD-10]) from 2013 to 2017 were included. Three subanalyses were performed to compare [1] patients with pathological history (prematurity, bronchopulmonary dysplasia [BPD] and congenital heart disease [CHD]), [2] diagnoses (pneumonia, acute bronchitis, and acute bronchiolitis), and [3] admission to the pediatric intensive care unit. Days of hospital stay, in-hospital complications, invasive medical procedure and mortality were analyzed.

STATISTICAL ANALYSIS

VRI hospitalization prevalence was described. For comparison between groups, Student's t-test, ANOVA and the Chi2 test were applied. To identify factors related to days of hospital stay, in-hospital complications and mortality, a linear and logistic regression model was performed.

RESULTS

A total of 66,304 hospitalizations were reported. The average age was 14.7 weeks; hospitalization events were higher in winter (39%), followed by autumn (27.3%). A total of 371 (0.56%) patients died. A total of 7068 (10.6%) hospitalized patients with pathological histories were identified. The presence of BPD (coefficient = 1.6), CHD (coefficient = 1.2), diagnosis of pneumonia (coefficient = 1.2), in-hospital complications (coefficient = 2.1) and invasive medical procedures (coefficient = 15.7) were the most common factors that increased the length of hospital stay. Risk factors for in-hospital complications and mortality were invasive medical procedure (OR = 3.3 & 11.7), BPD (OR = 1.8 & 1.6), CHD (OR = 4.6 & 3.4) and diagnosis of pneumonia (OR = 1.8 & 4.2).

CONCLUSIONS

Risk factors for morbidity and mortality in patients hospitalized for VRIs are BPD and CHD, diagnosis of pneumonia and invasive medical procedure.

RSV and non-RSV illness hospitalization in RSV immunoprophylaxis recipients: A systematic literature review

Respiratory syncytial virus (RSV) immunoprophylaxis (IP) has been shown to reduce RSV hospitalization rates in high-risk infants; however, it is unclear whether RSV IP is associated with increased risk of non-RSV disease, particularly non-RSV hospitalizations. We conducted a systematic literature review to understand the occurrences of non-RSV disease and/or non-RSV hospitalizations in published studies of RSV IP. Cochrane, Embase, and PubMed databases were searched and reviewed to summarize data regarding the incidence of RSV and non-RSV respiratory disease among RSV IP recipients and controls in randomized and non-randomized studies. Independent investigators screened and selected studies for inclusion. Risk-of-bias assessment was conducted to assess strength/validity of the data using the Jadad scoring system and Downs and Black quality assessment tool, where appropriate. Twenty studies were included for review (5 randomized controlled trials [RCTs]; 15 non-randomized studies). RCTs of RSV IP demonstrated reductions in RSV hospitalizations and all-cause hospitalizations, with no increase in hospitalizations for non-RSV disease. Non-randomized studies also demonstrated reduced RSV hospitalizations in RSV IP recipients but had mixed results in assessments of hospitalizations for non-RSV disease. When RSV IP recipients and controls were more similar in disease severity risk, results of non-randomized studies aligned more closely with RCTs. Observations of increased non-RSV hospitalization rates among RSV IP recipients in some non-randomized studies could be primarily explained by differences in the clinical characteristics between RSV IP recipients and controls.

Respiratory syncytial virus acute respiratory infection-associated hospitalizations in preterm Mexican infants: A cohort study

Background

Respiratory syncytial virus (RSV) is the leading cause of severe acute respiratory infections (ARI) in preterm infants. The incidence of RSV‐associated hospitalizations has not been defined in Mexico.

Objectives

To determine the incidence of ARI‐ and RSV‐associated hospitalizations in preterm infants during the first year of life.

Methods

Prospective cohort study of 294 preterm infants followed up through monthly telephone calls and routine outpatient visits. Hospitalized children were identified through daily visits to pediatric wards of participating hospitals and through telephone calls. Respiratory samples were tested for RSV by RT‐PCR.

Results

Mean gestational age of participating infants was 33 weeks. Ninety‐six infants were diagnosed with bronchopulmonary dysplasia (BPD) and 17 with congenital heart disease (CHD); 11 had both conditions. There were 71 hospitalization episodes in 53 infants. Respiratory samples for RSV detection were available in 44 hospitalization episodes, and the result was positive in 16 (36.3%). At least one hospitalization for ARI was recorded in 33 of 96 participants with BPD, in seven of 17 with CHD, and 18 of 192 infants without these diagnoses. Five (71.4%) of CHD infants who required admission also had BPD. RSV‐confirmed hospitalization rates were 9.4%, 5.9%, and 2.6% for infants with BPD, CHD, and otherwise healthy preterm infants, respectively. Attributable RSV admission frequencies were estimated to be 13.6%, 16.5%, and 4.1%, respectively.

Conclusions

Mexican preterm infants, particularly those with BPD, have high rates of ARI‐ and RSVassociated hospitalizations. Specific interventions to reduce the incidence of severe infections in this highrisk group are required.

The Impact of a History of Pre-maturity on Viral Respiratory Infections in Children Under 2 Years of Age: A Propensity Score-Matching Analysis of in-hospital Complications and Mortality

Introduction: A history of pre-maturity may be a risk factor for complications in patients under 24 months of age hospitalized for viral respiratory infections (VRIs). Objective: To identify the impact of a history of pre-maturity on in-hospital complications and mortality in patients under 24 months of age who were hospitalized for VRIs over a period of 5 years. Material and Methods: This was a propensity score-matched study. The database was compiled by physicians, electronically validated by engineers, and analyzed by statisticians. Patients diagnosed with VRIs (based on International Classification of Diseases [ICD-10]) codes B974, J12, J120-J129X, J168, J17, J171, J178, J20, J203-J209, J21, J210, J211, J218, J219, J22X, and J189) from 2013 to 2017 were enrolled in the study. The subjects were classified into two groups according to the absence or presence of a history of pre-maturity (P070, P072, P073). Patients with congenital heart disease (CHD) (Q20-Q26) were excluded. Length of hospital stay, in-hospital complications, surgical procedures, and mortality were analyzed. Statistical Analysis: Patients were matched according to age. For comparisons between groups, Student's t-tests and chi² tests were applied. A logistic regression model was constructed to identify factors related to in-hospital complications and mortality. Results: In total, 5,880 patients were eligible for inclusion in the analysis. The average patient age was 14.25 weeks. The presence of pre-maturity (coefficient = 1.16), male sex, bronchopulmonary dysplasia (BPD), in-hospital infectious complications (coefficient = 11.31), and invasive medical procedures (coefficient = 18.4) increased the number of days of hospitalization. Invasive medical procedures (OR = 6.13), a history of pre-maturity (OR = 2.54), and male sex (OR = 1.78) increased the risk for in-hospital complications. In-hospital infectious complications (OR = 84.2) and invasive medical procedures (OR = 58.4) were risk factors for mortality. Conclusions: A history of pre-maturity increased the length of hospital stay and the rate of in-hospital complications but did not increase mortality in patients under 24 months of age hospitalized for VRIs.

Palivizumab Prophylaxis among Infants at Increased Risk of Hospitalization due to Respiratory Syncytial Virus Infection in UAE: A Hospital-Based Study

Background

Respiratory syncytial virus (RSV) represents a significant public health burden and the leading cause of lower respiratory tract infections globally, and it is the major cause of hospitalization during the winter. We aimed to evaluate the effectiveness of palivizumab prophylaxis to reduce the hospitalization in children at high risk of RSV infection.

Methods

We performed a retrospective observational single-arm hospital-based study including five RSV seasons (September to March) from 2012 to 2017. We retrospectively included premature infants born at less than 35 weeks of gestation with chronic lungs disease or hemodynamic significant congenital heart disease for palivizumab prophylaxis against RSV infection according to the criteria presented.

Results

A total of 925 children were enrolled in the study over the five RSV seasons. Of them, 410 (44.3%) infants born at <32 weeks of gestation and 515 (55.6%) infants born at 32-35 weeks of gestation with mean (±SD) birth weight of 1104.8 ± 402.85 and 1842.5 ± 377.5, respectively. The compliance with the course of palivizumab was reported in 841 (90.9%) children. Of them, about 75 (8.9%) hospitalized children were reported, and 17 (2.02%) RSV positive children were detected. Hospitalization due to RSV infection was decreased from 9.23% in the 2012-2013 season to 0.67% in the 2016-2017 season.

Conclusion

This study demonstrated that palivizumab prophylaxis in children at high risk of developing RSV infection was effective in reducing the risk of hospitalization with a high compliance rate over the five RSV seasons.

Severe Respiratory Syncytial Virus Infection in Preterm Infants and Later Onset of Asthma

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of viral lower respiratory tract infections in infants. Preterm infants are at increased risk for hospitalization with RSV (RSV-H), but there are few data on the relationship between RSV-H and asthma in preterm infants, or any data stratified by gestational age, and most studies have short follow-up periods. We sought to evaluate the relationship between serious RSV illness and onset of asthma up to 5 years of age in a cohort of preterm children and to quantify this association.

METHODS

A retrospective birth cohort of preterm infants (29 weeks 0 days to 35 weeks 6 days gestational age) was constructed from a provincial population-based database, and children were followed forward for 5 years. Incidence rates of RSV-H and asthma were determined. In a Cox proportional hazards model, controlled for putative confounding factors for asthma, the hazard ratio and 95% CI of asthma in children with and without RSV-H was evaluated.

RESULTS

Among 3916 premature children, the incidence rate of RSV-H was 25/1000 infants. The cumulative incidence rate of asthma at 5 years of age in children with RSV-H was 57.9/1000 person-years compared with 36.7 in those without RSV-H; the adjusted hazards ratio for asthma in RSV-H infants was elevated at 1.58 (95% CI: 1.03-2.41).

CONCLUSIONS

In prematurely born children, there is a moderate association between severe RSV infection, as measured by RSV-H in the first year of life, and asthma up to 5 years of age.

Bronchiolitis Admissions in a Lebanese Tertiary Medical Center: A 10 Years' Experience

Bronchiolitis and more specifically respiratory syncytial virus (RSV) bronchiolitis is a leading cause of global childhood morbidity and mortality. Despite the previous identification of possible risk factors associated with the severity of bronchiolitis, the data from Lebanon remains limited. We described the burden of bronchiolitis hospitalizations in children under 5 years of age in a tertiary care center in Lebanon from October 2004 to October 2014 and identified the risk factors associated with severe bronchiolitis. This was a retrospective cohort study conducted at the American University of Beirut Medical Center. Records of children younger than 5 years of age admitted with a diagnosis of bronchiolitis were reviewed. More than half the patients were RSV positive. RSV bronchiolitis was found to be significantly associated with longer hospital stay compared to children with non-RSV bronchiolitis (P = 0.007). Children exposed to smoking had an increased risk for longer hospital stay (P = 0.002) and were more likely to require ICU admission (P < 0.001) and supplemental oxygen (P = 0.045). Congenital heart disease was found to be a significant risk factor for severe bronchiolitis (P < 0.005). Conclusion: Patients with RSV bronchiolitis had a longer hospital stay compared to patients with non-RSV bronchiolitis. Exposure to smoking was associated with a more severe and complicated RSV infection. Congenital heart disease was the only risk factor significantly associated with all markers of bronchiolitis disease severity.

Respiratory Syncytial Virus Hospitalizations among U.S. Preterm Infants Compared with Term Infants Before and After the 2014 American Academy of Pediatrics Guidance on Immunoprophylaxis: 2012-2016

OBJECTIVE

The objective of this study was to compare risk for respiratory syncytial virus (RSV) hospitalizations (RSVH) for preterm infants 29 to 34 weeks gestational age (wGA) versus term infants before and after 2014 guidance changes for immunoprophylaxis (IP), using data from the 2012 to 2016 RSV seasons.

STUDY DESIGN

Using commercial and Medicaid claims databases, infants born between July 1, 2011 and June 30, 2016 were categorized as preterm or term. RSVH during the RSV season (November-March) were identified for infants aged <6 months and rate ratios (RRs) for hospitalization comparing preterm and term infants were calculated. Difference-in-difference models were fit to evaluate the changes in hospitalization risks in preterm versus term infants from 2012 to 2014 seasons to 2014 to 2016 seasons.

RESULTS

In all seasons, preterm infants had higher RSVH rates than term infants. Seasonal RRs prior to the guidance change for preterm wGA categories versus term infants ranged from 1.6 to 3.4. After the guidance change, the seasonal RRs ranged from 2.6 to 5.6. In 2014 to 2016, the risk associated with prematurity of 29 to 34 wGA versus term was significantly higher than in 2012 to 2014 (P<0.0001 for commercial and Medicaid samples).

CONCLUSION

In infants aged <6 months, the risk for RSVH for infants 29 to 34 wGA compared with term infants increased significantly after the RSV IP recommendations became more restrictive.

The impact of respiratory viruses on lung health after preterm birth

Children born preterm, less than 37 weeks' gestation, are at increased risk of viral respiratory infections and associated complications both during their initial birth hospitalisation and in their first years following discharge. This increased burden of viral respiratory infections is likely to have long term implications for lung health and function in individuals born preterm, particularly those with bronchopulmonary dysplasia. Several hypotheses have been put forward to explain the association between early life viral respiratory infection and development of suboptimal lung health and function later in life following preterm birth. Although preterm infants with diminished lung function, particularly small airways, might be particularly susceptible to asthma and wheezing disorders following viral infection, there is evidence that respiratory viruses can activate number of inflammatory and airway re-modelling pathways. Therefore, the aim of this review is to highlight the perinatal and early life risk factors that may contribute to increased susceptibility to viral respiratory infections among preterm infants during early life and to understand how respiratory viral infection may influence the development of abnormal lung health and function later in life.

Seasonal peaks and risk factors of respiratory syncytial virus infections related hospitalization of preterm infants in Taiwan

Objectives

To assess the nationwide seasonal peaks, risk factors, and utilization of medical resources of respiratory syncytial virus-associated hospitalization (RSVH) in preterm infants in Taiwan.

Study design

A Taiwan nationwide birth cohort was extracted from the Birth Certificate Application Database during 2007–2009 and prospectively linked to the National Health Insurance database. We evaluated the seasonal peaks and risk factors (gestational age [GA], chronologic age [CA], and bronchopulmonary dysplasia [BPD]) associated with the RSVH of preterm infants. The length of hospital stays (LOS), care in intensive care unit (ICU), and use of mechanical ventilation (MV) were also analyzed.

Results

There is a total duration of 9 months of RSVH season in Taiwan, three seasonal peaks and two seasonal peaks of RSVH in preterm infants with BPD and without BPD, respectively. Preterm infants had significantly higher RSVH rate than term infants (2.6% vs 0.9%, p<0.0001). Preterm infants born at 29–35 weeks of gestational age (wGA) with BPD had significantly higher RSVH rate than those without BPD (p<0.0001). Preterm infants without BPD born at < 32 wGA had higher RSVH rate than those born at 33–35 wGA (p<0.0001). Overall, 56.4% of RSVH occurred within 9 months of CA. Preterm infants with BPD had significantly higher ICU admission rate within 18 months of CA (p<0.0001), MV usage within 12 months of CA (p<0.0001) and LOS within 18 months of CA (p<0.001) than those without BPD. RSVH occurred within 6 months of CA was significantly associated with higher ICU admission rate (p<0.0001), MV usage (p = 0.0002) and longer LOS (p<0.001) in preterm infants without BPD.

Conclusions

There is a total duration of 9 months of RSVH season in Taiwan. Preterm < 32 wGA, BPD, and CA within 6 months were risk factors of RSVH which also contribute to higher utilization of medical resources.

Respiratory viral infections in infancy and school age respiratory outcomes and healthcare costs

OBJECTIVES

To determine the impact of viral lower respiratory tract infections (LRTIs) in infancy including rhinovirus (RV) and infancy respiratory syncytial virus (RSV), on school age pulmonary function and healthcare utilization in prematurely born children.

WORKING HYPOTHESIS

School age respiratory outcomes would be worse and healthcare utilization greater in children who had viral LRTIs in infancy.

STUDY DESIGN

Prospective study.

SUBJECT SELECTION

A cohort of prematurely born children who had symptomatic LRTIs during infancy documented, was recalled.

METHODS

Pulmonary function was assessed at 5 to 7 years of age and health related costs of care from aged one to follow-up determined.

RESULTS

Fifty-one children, median gestational age 33⁺⁶ weeks, were assessed at a median (IQR) age 7.03 (6.37-7.26) years. Twenty-one children had no LRTI, 14 RV LRTI, 10 RSV LRTI, and 6 another viral LRTI (other LRTI). Compared to the no LRTI group, the RV group had a lower FEV₁ (P = 0.033) and the other LRTI group a lower FVC (P = 0.006). Non-respiratory medication costs were higher in the RV (P = 0.018) and RSV (P = 0.013) groups. Overall respiratory healthcare costs in the RV (£153/year) and RSV (£27/year) groups did not differ significantly from the no LRTI group (£56/year); the other LRTI group (£431/year) had higher respiratory healthcare costs (P = 0.042).

CONCLUSIONS

In moderately prematurely born children, RV and RSV LRTIs in infancy were not associated with higher respiratory healthcare costs after infancy. Children who experienced LRTIs caused by other respiratory viruses (including RV) had higher respiratory healthcare costs and greater pulmonary function impairment.

Global respiratory syncytial virus-associated mortality in young children (RSV GOLD): a retrospective case series

Background

Respiratory syncytial virus (RSV) infection is an important cause of pneumonia mortality in young children. However, clinical data for fatal RSV infection are scarce. We aimed to identify clinical and socioeconomic characteristics of children aged younger than 5 years with RSV-related mortality using individual patient data.

Methods

In this retrospective case series, we developed an online questionnaire to obtain individual patient data for clinical and socioeconomic characteristics of children aged younger than 5 years who died with community-acquired RSV infection between Jan 1, 1995, and Oct 31, 2015, through leading research groups for child pneumonia identified through a comprehensive literature search and existing research networks. For the literature search, we searched PubMed for articles published up to Feb 3, 2015, using the key terms “RSV”, “respiratory syncytial virus”, or “respiratory syncytial viral” combined with “mortality”, “fatality”, “death”, “died”, “deaths”, or “CFR” for articles published in English. We invited researchers and clinicians identified to participate between Nov 1, 2014, and Oct 31, 2015. We calculated descriptive statistics for all variables.

Findings

We studied 358 children with RSV-related in-hospital death from 23 countries across the world, with data contributed from 31 research groups. 117 (33%) children were from low-income or lower middle-income countries, 77 (22%) were from upper middle-income countries, and 164 (46%) were from high-income countries. 190 (53%) were male. Data for comorbidities were missing for some children in low-income and middle-income countries. Available data showed that comorbidities were present in at least 33 (28%) children from low-income or lower middle-income countries, 36 (47%) from upper middle-income countries, and 114 (70%) from high-income countries. Median age for RSV-related deaths was 5·0 months (IQR 2·3–11·0) in low-income or lower middle-income countries, 4·0 years (2·0–10·0) in upper middle-income countries, and 7·0 years (3·6–16·8) in high-income countries.

Interpretation

This study is the first large case series of children who died with community-acquired RSV infection. A substantial proportion of children with RSV-related death had comorbidities. Our results show that perinatal immunisation strategies for children aged younger than 6 months could have a substantial impact on RSV-related child mortality in low-income and middle-income countries.

Funding

Bill & Melinda Gates Foundation.

Palivizumab Prophylaxis for Respiratory Syncytial Virus: Examining the Evidence Around Value

Respiratory syncytial virus (RSV) infection is the most common cause of lower respiratory tract infection and the leading cause of hospitalization among young children, incurring high annual costs among US children under the age of 5 years. Palivizumab has been found to be effective in reducing hospitalization and preventing serious lower respiratory tract infections in high-risk infants. This paper presents a systematic review of the cost-effectiveness studies of palivizumab and describes the main highlights of a round table discussion with clinical, payer, economic, research method, and other experts. The objectives of the discussion were to (1) review the current state of clinical, epidemiology, and economic data related to severe RSV disease; (2) review new cost-effectiveness estimates of RSV immunoprophylaxis in US preterm infants, including a review of the field’s areas of agreement and disagreement; and (3) identify needs for further research.

The 2014-2015 National Impact of the 2014 American Academy of Pediatrics Guidance for Respiratory Syncytial Virus Immunoprophylaxis on Preterm Infants Born in the United States

OBJECTIVE

This article aims to compare respiratory syncytial virus (RSV) immunoprophylaxis (IP) use and RSV hospitalization rates (RSVH) in preterm and full-term infants without chronic lung disease of prematurity or congenital heart disease before and after the recommendation against RSV IP use in preterm infants born at 29 to 34 weeks' gestational age (wGA).

STUDY DESIGN

Infants in commercial and Medicaid claims databases were followed from birth through first year to assess RSV IP and RSVH, as a function of infant's age and wGA. RSV IP was based on pharmacy or outpatient medical claims for palivizumab. RSVH was based on inpatient medical claims with a diagnosis of RSV.

RESULTS

Commercial and Medicaid infants 29 to 34 wGA represented 2.9 to 3.5% of all births. RSV IP use in infants 29 to 34 wGA decreased 62 to 95% (p < 0.01) in the 2014-2015 season relative to the 2013-2014 season. Compared with the 2013-2014 season, RSVH increased by 2.7-fold (p = 0.02) and 1.4-fold (p = 0.03) for infants aged <3 months and 29 to 34 wGA in the 2014-2015 season with commercial and Medicaid insurance, respectively. In the 2014-2015 season, RSVH for infants 29 to 34 wGA were two to seven times higher than full-term infants without high-risk conditions.

CONCLUSION

Following the 2014 RSV IP guidance change, RSV IP use declined and RSVH increased among infants born at 29 to 34 wGA and aged <3 months.

The 2014-2015 National Impact of the 2014 American Academy of Pediatrics Guidance for Respiratory Syncytial Virus Immunoprophylaxis on Preterm Infants Born in the United States

OBJECTIVE

This article aims to compare respiratory syncytial virus (RSV) immunoprophylaxis (IP) use and RSV hospitalization rates (RSVH) in preterm and full-term infants without chronic lung disease of prematurity or congenital heart disease before and after the recommendation against RSV IP use in preterm infants born at 29 to 34 weeks' gestational age (wGA).

STUDY DESIGN

Infants in commercial and Medicaid claims databases were followed from birth through first year to assess RSV IP and RSVH, as a function of infant's age and wGA. RSV IP was based on pharmacy or outpatient medical claims for palivizumab. RSVH was based on inpatient medical claims with a diagnosis of RSV.

RESULTS

Commercial and Medicaid infants 29 to 34 wGA represented 2.9 to 3.5% of all births. RSV IP use in infants 29 to 34 wGA decreased 62 to 95% (p < 0.01) in the 2014-2015 season relative to the 2013-2014 season. Compared with the 2013-2014 season, RSVH increased by 2.7-fold (p = 0.02) and 1.4-fold (p = 0.03) for infants aged <3 months and 29 to 34 wGA in the 2014-2015 season with commercial and Medicaid insurance, respectively. In the 2014-2015 season, RSVH for infants 29 to 34 wGA were two to seven times higher than full-term infants without high-risk conditions.

CONCLUSION

Following the 2014 RSV IP guidance change, RSV IP use declined and RSVH increased among infants born at 29 to 34 wGA and aged <3 months.

Chronologic Age at Hospitalization for Respiratory Syncytial Virus Among Preterm and Term Infants in the United States

INTRODUCTION

Respiratory syncytial virus (RSV) is the leading cause of hospitalization among infants in the United States, and the risk for RSV hospitalizations is greater for infants born preterm. Recent studies in preterm and term infants have shown that RSV hospitalization rates vary considerably depending on infant chronologic age. This study sought to aggregate the data available from published literature and from nationally representative databases of US infant hospitalizations to generate a composite description of the effect of young chronologic age on RSV hospitalizations among US preterm and term infants by individual month of age.

METHODS

Data describing the relative incidence of RSV hospitalizations by individual month of chronologic age during the first year of life were obtained from recently published studies, the 2006-2011 National Inpatient Sample databases, and the 2006 and 2009 Kids Inpatient Databases.

RESULTS

All data sources showed that ≥20% of infant RSV hospitalizations occurred in the second month of life and >50% and >75% of RSV hospitalizations were observed during the first 3 and 6 months of life, respectively. These findings were consistent for both preterm and term infants.

CONCLUSION

Data from multiple sources demonstrate that the greatest risk of RSV hospitalization occurs during the first 6 months of life among US preterm and term infants. Strategies to prevent infant RSV hospitalizations should be targeted to infants during the first months of life.

FUNDING

AstraZeneca.

Efficacy of palivizumab prophylaxis on the frequency of RSV-associated lower respiratory tract infections in preterm infants: determination of the ideal target population for prophylaxis

Respiratory syncytial virus (RSV) prophylaxis in high-risk infants is an effective intervention for the prevention of severe disease. The aim of this study was to determine the ideal target preterm population that might benefit from palivizumab prophylaxis by establishing the main risk factors for acute RSV-related infections. Former premature infants born with a gestational age ≤37 weeks and ≤1 year of age at the beginning of the RSV season and admitted with respiratory infection were included. RSV status was evaluated by RSV strip test in all infants. RSV-positive and -negative infants were compared in terms of demographic features, risk factors, requirement of hospitalisation and palivizumab administration. A total of 202 preterm infants under 1 year of age were enrolled. The RSV test was positive in 34 (16.8%) infants. Maternal age was significantly lower in RSV-positive infants compared with RSV-negative infants (p = 0.03). RSV-positive infants were found to be significantly discharged during the RSV season (p = 0.03). RSV-positive infants required significantly higher rates of hospitalisation and need for mechanical ventilation. Of the RSV-positive infants, 28 (82%) had a gestational age ≥29 weeks. Seventeen (77%) RSV-positive infants that required hospitalisation were ≥29 weeks of gestation. All infants with a gestational age ≥29 weeks and without palivizumab prophylaxis developed RSV infection. Palivizumab prophylaxis should be implemented into guidelines to cover preterm infants with a gestational age >29 weeks. Palivizumab prophylaxis should also be considered in high-risk infants ≤6 months of age during the RSV season.

Effects of Chronologic Age and Young Child Exposure on Respiratory Syncytial Virus Disease among US Preterm Infants Born at 32 to 35 Weeks Gestation

Objective

To estimate the incidence of respiratory syncytial virus (RSV) disease as a function of chronologic age and exposure to young children in US preterm infants.

Methods

In the RSV Respiratory Events among Preterm Infants Outcomes and Risk Tracking (REPORT) study, preterm infants born at 32–35 weeks gestational age (wGA) were enrolled from 188 US clinics and followed September-May of 2009–2010 or 2010–2011. Infants with medically-attended acute respiratory illness had nasal/pharyngeal swabs collected for viral testing. Results of RSV tests conducted during routine clinical care were also collected. Event rates during November-March were modeled as a function of chronologic age and birth month using Poisson regression and adjusting for other covariates. Rates were calculated overall and for infants with and without exposure to young siblings or daycare attendance. Of 3317 infants screened, 1646 were enrolled as a consecutive sample. Infants with chronic lung disease of prematurity, hemodynamically significant congenital heart disease, life expectancy <6 months, or receiving or being considered for RSV immunoprophylaxis were excluded. 84% of patients completed the study. Demographics of the enrolled cohort were generally similar to those of US infants born at 32–35 wGA; infants 32–34 wGA, Hispanic infants, and infants of less-educated mothers were under-represented.

Results

Among 1642 evaluable infants, outpatient RSV lower respiratory illness incidence was highest at older ages, whereas RSV hospitalization and intensive care unit (ICU) admission were highest at younger ages. In all instances, young child exposure was associated with higher RSV incidence. The highest RSV hospitalization and ICU rates occurred among February-born infants with young child exposure, at 19.0 (95% CI, 13.5–27.0) and 6.5 (95% CI, 5.6–7.6) per 100 infant-seasons, respectively.

Conclusions

Preterm infants have a substantially elevated risk of RSV disease. Young age and exposure to other young children identify those at greatest risk of severe RSV disease.

Trial Registration

Clinicaltrials.gov: NCT00983606.

Defining the Risk and Associated Morbidity and Mortality of Severe Respiratory Syncytial Virus Infection Among Preterm Infants Without Chronic Lung Disease or Congenital Heart Disease

INTRODUCTION

The REGAL (RSV Evidence-a Geographical Archive of the Literature) series provide a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This second publication covers the risk and burden of RSV infection in preterm infants born at <37 weeks' gestational age (wGA) without chronic lung disease or congenital heart disease.

METHODS

A systematic review was undertaken for articles published between January 1, 1995 and December 31, 2015. Studies reporting data for hospital visits/admissions for RSV infection among preterm infants as well as studies reporting RSV-associated morbidity, mortality, and risk factors were included. Study quality and strength of evidence (SOE) were graded using recognized criteria.

RESULTS

2469 studies were identified of which 85 were included. Preterm infants, particularly those born at lower wGA, tended to have higher RSV hospitalization (RSVH) rates compared with otherwise healthy term infants (high SOE). RSVH rates ranged from ~5 per 1000 children to >100 per 1000 children with the highest rates shown in the lowest gestational age infants (high SOE). Independent risk factors associated with RSVH include: proximity of birth to the RSV season, living with school-age siblings, smoking of mother during pregnancy or infant exposure to environmental smoking, reduced breast feeding, male sex, and familial atopy (asthma) (high SOE). Predictive models can identify 32/33-35 wGA infants at risk of RSVH (high SOE).

CONCLUSION

RSV infection remains a major burden on Western healthcare systems and is associated with significant morbidity. Further studies focusing on the prevalence and burden of RSV in different gestational age cohorts, the changing risk of RSVH during the first year of life, and on RSV-related mortality in preterm infants are needed to determine the true burden of disease.

FUNDING

AbbVie.