Respiratory syncytial virus risk factors in late preterm infants

Respiratory Syncytial Virus Infections in Neonates: A Persisting Problem

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections in young infants. It is an enveloped, single-stranded, nonsegmented, negative-strand RNA virus, a member of the family Pneumoviridae. Globally, RSV is responsible for 2.3% of deaths among neonates 0-27 days of age. Respiratory syncytial virus infection is most common in children aged below 24 months. Neonates present with cough and fever. Respiratory syncytial virus-associated wheezing is seen in 20% infants during the first year of life of which 2-3% require hospitalization. Reverse transcriptase polymerase chain reaction (RT-PCR) gives fast results and has higher sensitivity compared with culture and rapid antigen tests and are not affected by passively administered antibody to RSV. Therapy for RSV infection of the LRT is mainly supportive, and preventive measures like good hygiene and isolation are the mainstay of management. Standard precautions, hand hygiene, breastfeeding and contact isolation should be followed for RSV-infected newborns. Recent AAP guidelines do not recommend pavilizumab prophylaxis for preterm infants born at 29-35 weeks without chronic lung disease, hemodynamically significant congenital heart disease and coexisting conditions. RSV can lead to long-term sequelae such as wheezing and asthma, associated with increased healthcare costs and reduced quality of life.

Exploring the adoption of less restricted criteria for respiratory syncytial virus prophylaxis in late preterm infants: insights from a retrospective analysis

Background

Preterm infants born between 33 and 35 weeks of gestational age (wGA) have been considered a "major underserved population" and ineligible to receive palivizumab (PLV), the only drug authorized to date for respiratory syncytial virus (RSV) prophylaxis, by current international guidelines. In Italy, such a vulnerable population is currently eligible for prophylaxis, and, in our region, specific risk factors are taken into consideration (SIN_Lazio score) to target prophylaxis for those at highest risk. Whether the adoption of less or more restrictive eligibility criteria for PLV prophylaxis would translate into differences in bronchiolitis and hospitalization incidence is not known.

Materials and methods

A retrospective analysis was conducted in 296 moderate-to-late preterm infants (born between 33 and 35⁺⁶ weeks) who were being considered for prophylaxis in two epidemic seasons: 2018-2019 and 2019-2020. The study participants were categorized according to both the SIN_Lazio score and the Blanken risk scoring tool (BRST), which was found to reliably predict RSV-associated hospitalization in preterm infants on the basis of three risk factor variables.

Results

Based on the SIN_Lazio score, approximately 40% of infants (123/296) would meet the criteria to be eligible for PLV prophylaxis. In contrast, none of the analyzed infants would be considered eligible for RSV prophylaxis on the basis of the BRST. A total of 45 (15.2%) bronchiolitis diagnoses were recorded on average at 5 months of age in the overall population. Almost seven out of 10 (84/123) patients exhibiting ≥3 risk factors to be eligible for RSV prophylaxis according to SIN_Lazio criteria would not be receiving PLV if they were categorized on the basis of the BRST. Bronchiolitis occurrence in patients with a SIN_Lazio score ≥3 was approximately 2.2 times more likely than that in patients with a SIN_Lazio score <3. PLV prophylaxis has been associated with a 91% lower risk of requiring a nasal cannula.

Conclusion

Our work further supports the need for targeting late preterm infants for RSV prophylaxis and calls for an appraisal of the current eligibility criteria for PLV treatment. Therefore, adopting less restrictive criteria may ensure a comprehensive prophylaxis of the eligible subjects, thus sparing them from avoidable short- and long-term consequences of RSV infection.

Impact of breastfeeding on the incidence and severity of respiratory syncytial virus (RSV)-associated acute lower respiratory infections in infants: a systematic review highlighting the global relevance of primary prevention

BACKGROUND

Respiratory syncytial virus (RSV) is the principal cause of acute lower respiratory infections (ALRI) among infants worldwide, and an important cause of morbidity, hospitalisation and mortality. While infants are universally exposed to RSV, most mortality occurs among normal term infants from low-income and middle-income countries. Breastfeeding has been suggested to have a protective effect against RSV infection. This study aims to determine the association of breastfeeding on the frequency and severity of RSV-associated ALRI among infants.

METHODS

A systematic review was conducted using keywords and Medical Subject Headings on MEDLINE, PubMed, Google Scholar, EMBASE, MedRxiv and Cochrane Central Register of Controlled Trials. Full-text articles published in English from 2000 to 2021 that studied exclusively or partially breastfed infants who developed RSV-associated ALRI <12 months of age were included. Covidence software-based evidence extraction and Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol guidelines were followed. Quality of evidence was analysed using UK National Service Framework grading and the risk-of-bias assessment using Robvis.

RESULTS

Among 1368 studies screened, 217 qualified full-text review and 198 were excluded based on pre-agreed criteria. Nineteen articles published from 12 countries that included 16 787 infants from 31 countries (of which 8 middle-income) were retained for analysis. Results indicate that non-breastfeeding practices pose a significant risk for severe RSV-associated ALRI and hospitalisation. Exclusive breastfeeding for >4-6 months significantly lowered hospitalisation, length of stay, supplemental oxygen demand and admission to intensive care units.

CONCLUSION

In the context of no effective or standardised treatment for established RSV-associated ALRI, available evidence suggest that breastfeeding is associated with lower frequency and severity of RSV-associated ALRI, based on observational studies of variable grades of evidence and risk-of-bias. With both exclusive and partial breastfeeding benefiting infants who develop RSV-associated ALRI, breastfeeding should be promoted globally as an adjunct primary prevention; in addition to emerging immunoprophylaxis and maternal immunisation strategies.

Follow-Up of Low Birth Weight Preterm Infants After Hospital Discharge: Incidence and Reasons for Rehospitalization

OBJECTIVES

The rehospitalization frequency/indications of low birth weight (LBW) preterms and the effect of rehospitalization on growth and neurodevelopment were investigated.

METHODS

LBW preterms discharged from NICU were prospectively followed until the corrected age of 1 year. Infants rehospitalized after discharge were defined as the study group and those not rehospitalized as the control group. The frequency, duration and etiology of rehospitalization were investigated and the effects of neonatal complications, surgery and socio-demographic status on rehospitalization were assessed.

RESULTS

The study and the control group included 113 and 217 infants, respectively. Infants in the study group were rehospitalized 247 times in total. Rehospitalization was significantly higher in the male gender (39.7% vs. 28.9%, p < 0.05). Hyperbilirubinemia-anemia, anemia-surgery and pulmonary-other infections were the most common indications for rehospitalization in the 0-14 days, 15 days to 2 months and 2-12 months, respectively. Intrauterine growth had no impact on rehospitalization. Somatic growth and neurodevelopment were significantly delayed in the study group (p < 0.05).

CONCLUSION

Birth weight and gestational week are the most important determinants of rehospitalization. Rehospitalized preterm infants have significant deficits in both somatic growth and neurodevelopment despite high-quality follow-up care.

RSV prophylaxis in premature infants

Infants born prematurely before 37 weeks of gestational age (GA) have particular anatomical, immunological and metabolic characteristics that predispose them, even in the absence of diseases at birth, to severe morbidity. Respiratory syncytial virus (RSV) is the leading cause of hospitalization for lower respiratory tract infections (LRTI) in the first year of life, as well as an important cause of respiratory outcomes as recurrent wheezing in industrialized countries or mortality in developing countries. Prematurity is an important risk factor for hospitalization for severe RSV disease, but epidemiological, environmental and demographic risk factors also play a role in RSV infection. Currently, there is no effective antiviral therapy for the treatment of RSV infection, nor the possibility of using maternal immunization or vaccination of children to prevent infection, although numerous preclinical and clinical studies are still ongoing. Passive immunization with palivizumab has been shown to be safe and effective in preventing RSV hospitalization in children at greater risk of contracting a serious infection. Costs associated with palivizumab prophylaxis and its monthly intramuscularly administration has prompted many health institutions of different countries to implement specific recommendations, with the aim of protecting at risk infants for whom RSV infection is likely to cause serious illness or death. The cost-effectiveness ratio of prophylaxis, related to reduce hospitalization costs and the impact of the burden of RSV disease worldwide, greatly affects the drafting and the adoption of specific recommendations and the adherence to them, concerning the passive immunization with palivizumab.

Evaluation of recent New Vaccine Surveillance Network data regarding respiratory syncytial virus hospitalization rates in US preterm infants

In July 2014, the Committee on Infectious Diseases (COID) updated their guidance on the use of palivizumab, recommending against use in preterm infants 29 to 35 weeks' gestational age (wGA). A primary data source cited to support this significant change was the low respiratory syncytial virus (RSV) hospitalization rate observed in the subpopulation of preterm (<37 wGA) infants evaluated from 2000 to 2005 through the New Vaccine Surveillance Network (NVSN). Here we critically appraise the preterm infant data from the NVSN in the context of data regarding the use of palivizumab in this same time period. Data from the NVSN, an analysis of Florida Medicaid data, and a national survey of US in-hospital palivizumab administration demonstrated that during 2001 to 2007, palivizumab was administered to 59% to 83% of preterm infants born at <32 wGA and 21% to 27% of all preterm infants (<37 wGA). When the NVSN data regarding incidence of RSV hospitalization in preterm infant subgroups were evaluated as a function of chronologic age, preterm infants <32 wGA showed a paradoxical increase in RSV hospitalization with older age, with the highest risk of RSV hospitalization occurring at 18 to 23 months of age. This pattern is most consistent with a reduction in RSV hospitalizations in <32 wGA infants in the first 12 to 18 months of life due to high palivizumab use at these young ages. The NVSN data were not designed to and cannot accurately describe RSV disease burden in preterm infants given the small size of the analyzed subpopulation and the high use of palivizumab during the study period.

Revised recommendations concerning palivizumab prophylaxis for respiratory syncytial virus (RSV)

Respiratory Syncytial Virus infections are one of the leading causes of severe respiratory diseases that require hospitalization and, in some cases, intensive care. Once resolved, there may be respiratory sequelae of varying severity. The lack of effective treatments for bronchiolitis and the lack of vaccines for RSV accentuate the role of prevention in decreasing the impact of this disease. Prevention of bronchiolitis strongly relies on the adoption of environment and the hygienic behavior measures; an additional prophylactic effect may be offered, in selected cases, by Palivizumab, a humanized monoclonal antibody produced by recombinant DNA technology, able to prevent RSV infection by blocking viral replication.After many years the Italian Society of Neonatology, on the basis of the most recent scientific knowledge, has decided to revise recommendations for the use of palivizumab in the prevention of RSV infection.

Modeling the Potential Impact of the 2014 American Academy of Pediatrics Respiratory Syncytial Virus Prophylaxis Guidance on Preterm Infant RSV Outcomes

INTRODUCTION

The American Academy of Pediatrics (AAP) Committee on Infectious Diseases issued updated guidance on respiratory syncytial virus (RSV) prophylaxis in 2014. This report models the potential impact of the new guidance on RSV outcomes in preterm infants 29-34 weeks' gestational age (wGA) without chronic lung disease in the United States.

METHODS

The number of preterm infants was estimated using 2012 natality data. Palivizumab utilization prior to the 2014 guidance update was estimated using 2013-2014 specialty pharmacy utilization data. Low, moderate, and high RSV hospitalization (RSVH) rates as well as average hospital length of stay, intensive care unit (ICU) admissions and mechanical ventilation (MV) frequencies were derived from published observational studies. Palivizumab efficacy was derived from two randomized clinical trials. RSV events that would be attributable to the 2014 guidance change were calculated for preterm infants 29-31 and 32-34 wGA.

RESULTS

Annual number of infants 29-34 wGA surviving the neonatal period was estimated at 123,687. Of these, an estimated 44,712 (37%) would receive palivizumab based on the 2012 guidance. The annual number of RSVH among infants 29-34 wGA would increase from 3580 under the 2012 guidance to 6166 under the 2014 guidance based on moderate rates. This would result in an additional 24,440 hospitalization days, 1162 ICU admissions, and 584 MV events among this population.

CONCLUSIONS

Based on published historical and contemporary data on RSVH rates in preterm infants 29-34 wGA, the 2014 AAP guidance is expected to result in additional burden to the healthcare system and families of preterm infants. The impact of the new guidance will be difficult to detect among the overall infant population, particularly in settings without routine testing for RSV, but the impact will be substantial for the small high-risk population affected by the changes.

FUNDING

AstraZeneca.

Obesity and bronchial obstruction in impulse oscillometry at age 5-7 years in a prospective post-bronchiolitis cohort

BACKGROUND AND AIMS

Obesity has been linked with asthma symptoms, need for asthma treatment and reduced lung function but not with increased bronchial reactivity in children. The aim of this study was to evaluate the association between previous or current weight status and current lung function and bronchial reactivity to exercise at early school age.

METHODS

Ninety-nine children hospitalized for bronchiolitis at the age of less than 6 months were studied with impulse oscillometry (IOS) at the mean age of 6.3 years. Data on birth weight and weight gain in infancy before hospitalization were collected during hospitalization. Current weight and height data were transformed into age- and sex-specific height-related body mass index z scores (zBMI) using the Finnish national population-based weight and height data as reference.

RESULTS

Some significant though only low or modest correlations were found between current zBMI and baseline, post-exercise and post-bronchodilator IOS values in adjusted linear regression analysis. Seven obese children by zBMI had higher post-bronchodilator airway impedance (Zrs) and resistance (Rrs) at 5 Hz and lower post-bronchodilator frequency dependency of resistance (dRrs/df) than normal weight children. There were no significant differences in responses to exercise or to bronchodilators between currently obese or overweight children and normal weight children. Birth weight less than 3,000 g was associated with larger exercise-induced changes in Zrs and Rrs at 5 Hz, and in reactance (Xrs) at 5 Hz, than those with birth weight more than 3,000 g.

CONCLUSIONS

Preliminary evidence was found that obesity may be associated with airway obstruction, but not with bronchial hyper-reactivity.

The effect of birth month on the risk of respiratory syncytial virus hospitalization in the first year of life in the United States

BACKGROUND

Respiratory syncytial virus (RSV) is the most common cause of severe respiratory illness in infants. To help direct targeted interventions and future RSV vaccine programs, we examined risk of RSV-related hospitalization by infant age and birth month.

METHODS

We conducted Poisson regression analyses to evaluate birth month as a risk factor for RSV-related pediatric hospitalizations (identified by any mention of ICD-9-CM diagnosis codes: 466.11, 480.1 or 079.6) from State Inpatient Data in Arizona, Iowa, New York, Oregon and Wisconsin between July 1996 and June 2006. We used an age cohort approach to compute total relative risk of RSV during the first year of life.

RESULTS

We identified 82,296 RSV-related infant hospital admissions, corresponding to 13.9 per 1000 person-years among infants <12 months of age. Of these, 42% of the patients were female and 73% were <6 months old. One-month-old infants born in January were ~10 times more at risk for RSV-related hospitalization than 1-month-old infants born in October [relative risk: 9.8 (7.8-12.4)]. Across the first year of life, infants born in December and January had a 2- and 3-fold higher risk, respectively, of an RSV-related hospitalization event than infants born in July.

CONCLUSIONS

Birth month and age at admission impacted the risk of RSV-related hospitalization within the first year of life in 5 states we investigated. As RSV vaccine candidates are currently under investigation in clinical trials, our findings help identify ideal RSV vaccine schedules to prevent early and severe events while improving the use of expensive prophylactic drugs.

Melatonin: its possible role in the management of viral infections--a brief review

Melatonin, a versatile molecule, is synthesized by the pineal gland but also by other organs, including gastrointestinal tract, retina, thymus, bone marrow, and by leukocytes. Besides playing an important role in various functions of the body, including sleep and circadian rhythm regulation, melatonin also shows immunoregulatory, free radical scavenger and antioxidant functions. Because of these latter characteristics melatonin has also been found to be effective in fighting viral infections in a variety of experimental animal and in vitro studies. These data suggest a possible therapeutic potential of melatonin in human virus-induced disorders.

The use of humanized monoclonal antibodies for the prevention of respiratory syncytial virus infection

Monoclonal antibodies are widely used both in infants and in adults for several indications. Humanized monoclonal antibodies (palivizumab) have been used for many years for the prevention of respiratory syncytial virus infection in pediatric populations (preterm infants, infants with chronic lung disease or congenital heart disease) at high risk of severe and potentially lethal course of the infection. This drug was reported to be safe, well tolerated and effective to decrease the hospitalization rate and mortality in these groups of infants by several clinical trials. In the present paper we report the development and the current use of monoclonal antibodies for prophylaxis against respiratory syncytial virus.

Postnatal catch-up fat after late preterm birth

BACKGROUND

Late preterm birth accounts for 70% of preterm births. The aim of the study was to investigate the postnatal weight gain and weight gain composition changes in a cohort of late preterm infants.

METHODS

A total of 49 late preterm infants (mean birth weight 2,496 ± 330 g and gestational age 35.2 ± 0.7 wks) underwent growth and body composition assessment by an air displacement plethysmography system on the fifth day of life, at term, and at 1 and 3 mo of corrected age. The reference group was composed of 40 healthy, full-term, breast-fed infants.

RESULTS

The late preterm infants showed a Δ fat mass gain between birth and term-corrected age equal to 182%. As compared with full-term infants, at term and 1 mo of corrected age mean weight (3,396 ± 390 vs. 3,074 ± 409 g and 4,521 ± 398 vs. 4,235 ± 673 g, respectively) and percentage of fat mass (16.1 ± 4.6 vs. 8.9 ± 2.9 and 22.6 ± 4.2 vs. 17.4 ± 4.0, respectively) were significantly higher in late preterm infants, whereas no difference among groups was found at 3 mo.

CONCLUSION

Rapid postnatal catch-up fat was found in these infants. Further studies are needed to investigate whether this short-term increase in fat mass may modulate the risk of chronic diseases or represent an adaptive mechanism to extrauterine life.

Respiratory distress syndrome at birth is a risk factor for hospitalization for lower respiratory tract infections in infancy

BACKGROUND

Respiratory distress syndrome (RDS) and hospitalization for lower respiratory tract infection (LRTI; specifically, respiratory syncytial virus) are important causes of morbidity in infancy. Whether RDS at birth is an independent risk factor for LRTI is unknown. This study estimated the risk of LRTI-related hospitalization among late preterm infants with a history of RDS.

METHODS

The population-based cohort from Québec included all late preterm infants (32-36 weeks gestational age) born in 1996 to 1997. RDS was identified by International Classification of Diseases, Ninth Revision code 769, and a comparison cohort generated from all without RDS. A multivariable model estimated the adjusted odds ratio of LRTI-related hospitalization among late preterm infants with a history of RDS; and the incidence and increased risk of childhood chronic respiratory morbidity was calculated.

RESULTS

Of the 7488 late preterms, 459 (6.1%) had a history of RDS; 525 late preterms (7.0%) were hospitalized for LRTI in infancy, including 57 (12.4%) with RDS. The adjusted odds ratio for LRTI-related hospitalization associated with RDS was 1.6 (1.2-2.2). Other significant risk factors included male sex, or diagnosis of other respiratory conditions, diaphragm anomalies, bacteremia, intraventricular hemorrhage, congenital heart disease or respiratory system anomalies. Late preterm infants with a history of RDS were also at a significantly increased risk of childhood chronic respiratory morbidity.

CONCLUSIONS

Late preterms with a history of RDS are at a 60% increased risk of LRTI-related hospitalization in infancy compared with late preterm infants without RDS. Such infants may benefit from interventions decreasing the risk of contracting respiratory viruses causing acute LRTI.

A decade of respiratory syncytial virus epidemiology and prophylaxis: translating evidence into everyday clinical practice

Respiratory syncytial virus (RSV) is a common infection in infancy, with nearly all children affected by two years of age. Approximately 0.5% to 2.0% of all children are hospitalized with lower respiratory tract disease, of which 50% to 90% have bronchiolitis and 5% to 40% have pneumonia. Morbidity and mortality are highest in children with nosocomial infection and in those with underlying medical illnesses such as cardiac and chronic lung disease. Aboriginal children residing in remote northern regions are specifically considered to be at high risk for hospitalization due to RSV infection. Thorough hand washing and health education are the principal strategies in primary prevention. In the absence of a vaccine, palivizumab prophylaxis is currently the best intervention to reduce the burden of illness and RSV-related hospitalization in high-risk children. Health care professionals should provide palivizumab prophylaxis cost effectively in accordance with recommendations issued by pediatric societies and national advisory bodies. The present article reviews the epidemiology of RSV infection and the short- and long-term impact of disease in high-risk infants and special populations. Prevention strategies and treatment are discussed based on the existing scientific evidence, and future challenges in the management of RSV infection are addressed.

Neonatal outcomes in a population of late-preterm infants

The late-preterm infants are a group of premature steadily increasing, different from term infants as immature in terms of respiratory, metabolic, neurological, and immunological features. They may present at birth and during the first week of life various diseases and brain lesions echographically evident. We analyzed the neonatal outcomes of 417 late-preterm infants, born in our Department of Neonatology in a period of two and a half years, evaluating respiratory problems (RDS, transient tachypnea, pneumonia, pneumothorax, and apnea), metabolic problems (hypoglycemia, hypomagnesemia, hypo-hypernatremia, dehydration, hypocalcemia, and hyperbilirubinemia), infections, neurological symptoms associated with electrolyte disturbances, the disease patterns observed by ultrasound examination of the brain, the kidney ultrasound images, genital malformations.

Local cytokine response upon respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the leading cause of childhood hospitalization and respiratory distress and has been recognized for several decades as a major health and economic burden worldwide. This virus has developed several virulence mechanisms to impair the establishment of a protective immune response to re-infection. Accordingly, inefficient immunological memory is usually generated after exposure to this pathogen. Furthermore, it has been shown that RSV can actively promote the induction of an inadequate cellular immune response at the site of infection that causes exacerbated inflammation in the respiratory tract. Such an inflammatory response is both inefficient for clearing the virus and can be responsible for detrimental symptoms, such as asthma and wheezing. Recent data suggest that RSV possesses molecular mechanisms to induce the secretion of pro-inflammatory cytokines that modulate the immune response and impair viral clearance by reducing IFN-γ production. Here, we discuss recent research leading to the identification of RSV virulence factors that are responsible of promoting a pro-inflammatory environment at the airways and their implications on pathogenicity.