Evaluation of case definitions for estimation of respiratory syncytial virus associated hospitalizations among children in a rural community of northern India

Comparative study on the epidemiological characteristics and hazards of respiratory syncytial virus and influenza virus infections among elderly people

OBJECTIVE

To investigate the epidemiological characteristics and infections of respiratory syncytial virus (RSV) and influenza viruses in hospitalized elderly patients with respiratory tract infections in Suzhou City, China, and to compare the differences in clinical characteristics and economic burden associated with these two infections.

METHODS

In this prospective study, pathogenetic testing and clinical data for hospitalized patients aged 60 years and older with respiratory tract infections were collected in five hospitals through stratified cluster sampling from December 2023 to May 2024. Comparative study on epidemic characteristics, clinical features and costs of cases who infected RSV alone and influenza alone were conducted.

RESULTS

Among 1,894 cases included, the RSV positivity rate was 5.91% during the 2023-2024 winter-spring season, while the influenza positivity rate was 9.61%. RSV-B was the predominant subtype of RSV, and influenza A (primarily H3N2) was the dominant strain among the influenza-positive cases. Compared with cases infected influenza virus alone, those infected RSV alone had lower occurrence frequency of fever (18.8% vs. 35.7%, P = 0.004), higher occurrence frequency of complications of lower respiratory tract infections (70.8% vs. 54.8%, P = 0.011), higher direct medical costs ($996.2 vs. $841.1, P = 0.017) and total costs ($1019.7 vs. $888.1, P = 0.036). RSV single infection is more common in female cases (P = 0.007) and diabetic cases (P = 0.007) than influenza virus single infection.

CONCLUSIONS

During the winter and spring months, RSV is the second most common pathogen after influenza virus among older adults hospitalized for respiratory infections in Suzhou, China. Patients infected RSV are more likely to develop complications with lower respiratory tract infections and have higher medical costs than the influenza. RSV infection in the elderly should be emphasized, especially in female patients and diabetic patients.

Severe respiratory syncytial virus infection in children: burden, management, and emerging therapies

The global burden of respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) in young children is high. The RSV prevention strategies approved in 2023 will be essential to lowering the global disease burden. In this Series paper, we describe clinical presentation, burden of disease, hospital management, emerging therapies, and targeted prevention focusing on developments and groundbreaking publications for RSV. We conducted a systematic search for literature published in the past 15 years and used a non-systematic approach to analyse the results, prioritising important papers and the most recent reviews per subtopic. Annually, 33 million episodes of RSV LRTI occur in children younger than 5 years, resulting in 3·6 million hospitalisations and 118 200 deaths. RSV LRTI is a clinical diagnosis but a clinical case definition and universal clinical tool to predict severe disease are non-existent. The advent of molecular point-of-care testing allows rapid and accurate confirmation of RSV infection and could reduce antibiotic use. There is no evidence-based treatment of RSV, only supportive care. Despite widespread use, evidence for high-flow nasal cannula (HFNC) therapy is insufficient and increased paediatric intensive care admissions and intubation indicate the need to remove HFNC therapy from standard care. RSV is now a vaccine-preventable disease in young children with a market-approved long-acting monoclonal antibody and a maternal vaccine targeting the RSV prefusion protein. To have a high impact on life-threatening RSV infection, infants at high risk, especially in low-income and middle-income countries, should be prioritised as an interim strategy towards universal immunisation. The implementation of RSV preventive strategies will clarify the full burden of RSV infection. Vaccine probe studies can address existing knowledge gaps including the effect of RSV prevention on transmission dynamics, antibiotic misuse, the respiratory microbiome composition, and long-term sequalae.

Characterizing human respiratory syncytial virus among children admitted with acute respiratory tract infections from 2019 to 2022

Respiratory syncytial virus is a major causative agent of lower respiratory tract infection in children, especially infants with substantial morbidity and mortality implications. The virus undergoes continuous evolution documented by accumulation of mutations in the glycoprotein gene necessitating vigilant surveillance to provide essential data to epidemiologists and researchers involved in development of vaccines. This study was aimed to perform molecular characterization of respiratory syncytial virus (RSV) among children ≤ 5 years admitted in hospital. In the current study we observed RSV-A (2019 (n = 95) and 2021 (n = 61) seasons) and RSV-B (2022 season (n = 68)). Phylogenetic analysis revealed all RSV-A strains (n = 47) to be GA.2.3.5 and RSV-B (n = 22) were classified as GB.5.0.5a. Selection pressure analysis identified one positive (P274L/V) and one negative site (P230T) in RSV-A, while in RSV-B there was only one negatively selected site (S295). This study spanning over three seasons contributes to RSV evolutionary dynamics in India emphasizing the importance of on-going surveillance to inform effective public health strategies and vaccine development efforts.

Exploring the effect of clinical case definitions on influenza vaccine effectiveness estimation at primary care level: Results from the end-of-season 2022-23 VEBIS multicentre study in Europe

BACKGROUND

Within influenza vaccine effectiveness (VE) studies at primary care level with a laboratory-confirmed outcome, clinical case definitions for recruitment of patients can vary. We used the 2022-23 VEBIS primary care European multicentre study end-of-season data to evaluate whether the clinical case definition affected IVE estimates.

METHODS

We estimated VE using a multicentre test-negative case-control design. We measured VE against any influenza and influenza (sub)types, by age group (0-14, 15-64, ≥65 years) and by influenza vaccine target group, using logistic regression. We estimated IVE among patients meeting the European Union (EU) acute respiratory infection (ARI) case definition and among those meeting the EU influenza-like illness (ILI) case definition, including only sites providing information on specific symptoms and recruiting patients using an ARI case definition (as the EU ILI case definition is a subset of the EU ARI one).

RESULTS

We included 24 319 patients meeting the EU ARI case definition, of whom 21 804 patients (90 %) meet the EU ILI case definition, for the overall pooled VE analysis against any influenza. The overall and influenza (sub)type-specific VE varied by ≤2 % between EU ILI and EU ARI populations.

DISCUSSION

Among all analyses, we found similar VE estimates between the EU ILI and EU ARI populations, with few (10%) additional non-ILI ARI patients recruited. These results indicate that VE in the 2022-23 influenza season was not affected by use of a different clinical case definition for recruitment, although we recommend investigating whether this holds true for next seasons.

Novel Approach for Detecting Respiratory Syncytial Virus in Pediatric Patients Using Machine Learning Models Based on Patient-Reported Symptoms: Model Development and Validation Study

BACKGROUND

Respiratory syncytial virus (RSV) affects children, causing serious infections, particularly in high-risk groups. Given the seasonality of RSV and the importance of rapid isolation of infected individuals, there is an urgent need for more efficient diagnostic methods to expedite this process.

OBJECTIVE

This study aimed to investigate the performance of a machine learning model that leverages the temporal diversity of symptom onset for detecting RSV infections and elucidate its discriminatory ability.

METHODS

The study was conducted in pediatric and emergency outpatient settings in Japan. We developed a detection model that remotely confirms RSV infection based on patient-reported symptom information obtained using a structured electronic template incorporating the differential points of skilled pediatricians. An extreme gradient boosting-based machine learning model was developed using the data of 4174 patients aged ≤24 months who underwent RSV rapid antigen testing. These patients visited either the pediatric or emergency department of Yokohama City Municipal Hospital between January 1, 2009, and December 31, 2015. The primary outcome was the diagnostic accuracy of the machine learning model for RSV infection, as determined by rapid antigen testing, measured using the area under the receiver operating characteristic curve. The clinical efficacy was evaluated by calculating the discriminative performance based on the number of days elapsed since the onset of the first symptom and exclusion rates based on thresholds of reasonable sensitivity and specificity.

RESULTS

Our model demonstrated an area under the receiver operating characteristic curve of 0.811 (95% CI 0.784-0.833) with good calibration and 0.746 (95% CI 0.694-0.794) for patients within 3 days of onset. It accurately captured the temporal evolution of symptoms; based on adjusted thresholds equivalent to those of a rapid antigen test, our model predicted that 6.9% (95% CI 5.4%-8.5%) of patients in the entire cohort would be positive and 68.7% (95% CI 65.4%-71.9%) would be negative. Our model could eliminate the need for additional testing in approximately three-quarters of all patients.

CONCLUSIONS

Our model may facilitate the immediate detection of RSV infection in outpatient settings and, potentially, in home environments. This approach could streamline the diagnostic process, reduce discomfort caused by invasive tests in children, and allow rapid implementation of appropriate treatments and isolation at home. The findings underscore the potential of machine learning in augmenting clinical decision-making in the early detection of RSV infection.

Circulation patterns and molecular epidemiology of human respiratory syncytial virus over five consecutive seasons in Morocco

Background

Respiratory syncytial virus (HRSV) is the leading cause of respiratory tract infections in infants and young children. we investigated the prevalence and characteristics of HRSV in Morocco and explored trends in circulating genotypes through partial G gene analysis of HRSV strains prevalent from 2012 to 2017.

Methods

Respiratory samples were gathered from both outpatients and inpatients meeting ILI or SARI case definitions. The patients' ages varied from 1 month to 99 years old. Nucleic acids were extracted and HRSV type/subtype was detected by RT-qPCR. A subset of positive samples was randomly selected in each epidemic year, the complete viral genome was sequenced, phylogenetic analysis was performed using the MEGA7 program and the genotypes were confirmed.

Results

The 3679 specimens were collected from 2012 to 2017, of which 726 (19.7%) were positive for HRSV. The 35% (257/726) of HRSV-positives were of the HRSV-A subtype, while the HRSV-B subtype accounted for 61% (442/726). The co-infection rate was 3.7% (27/726). The virus circulates in a periodic pattern, where epidemics occur during the fall months through early spring. HRSV genotype was confirmed in 127 specimens (56 HRSV-A and 71 HRSV-B). Based on phylogenetic analysis, all HRSV-A were ON1 genotype, and HRSV-B were mostly BA9 genotype. HRSV-B belonging to the BA10 genotype was detected in 2012 exclusively.

Conclusions

BA9, BA10, and ON1 were the only HRSV genotypes detected between 2012 and 2017. Variations in the G gene amino acid chain were identified in local strains, which suggests an increased need for continuous genomic surveillance.

Reclassification of respiratory syncytial virus genotypes in India

Respiratory syncytial virus (RSV) is known to be the major cause of lower respiratory tract infections in infants and in the elderly. RSV was recently reclassified and simplified into three genotypes of the RSV-A subgroup (GA1-GA3) and into seven genotypes of the RSV-B subgroup (GB1-GB7). This classification strategy was not implemented globally. This study intended to reclassify the sequences that were submitted in GenBank till September 2021 from India. The gene sequences of the ectodomain region, second hypervariable region (SHR), and the partial second hypervariable region (PSHR) of the G gene were selected for the analysis. 25 ectodomain, 36 s hypervariable, and 19 partial second hypervariable regions of the RSV-A subgroup and 42-ectodomain, 49-s hypervariable region and 11-partial second hypervariable region of RSV-B subgroup were used for phylogenetic analysis. P-distance was calculated to support the genotype determination done by phylogenetic analysis. Phylogenetic analysis revealed that GA2.3.1, GA2.3.3, GA2.3.4, GA2.3.5, and GA2.3.6b lineages of GA2 genotype for RSV-A; and GB5.0.1, GB5.0.2, GB5.0.3, GB5.0.4a, GB5.0.4c, GB5.0.5a, GB5.0.5c lineages of GB5 genotype and GB7 genotype for RSV-B were that circulated in India. This work has implication for RSV vaccine research, and also for strategies for the prevention and control of RSV infection in humans.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-022-00802-x.

Systematic literature review of the signs and symptoms of respiratory syncytial virus

Respiratory syncytial virus (RSV) is responsible for over 30 million lower respiratory tract infections (LRTIs) and 3 million hospitalizations worldwide each year. Despite the risk RSV poses to young children, older adults, and individuals with comorbidities or suppressed immunity, there is limited understanding of RSV symptom presentation across these at-risk groups, and there is no vaccine for RSV. We conducted two systematic literature reviews (SLRs) of studies that document signs and symptoms (S&S) of RSV in (1) children aged ≤5 years and (2) immunocompromised adolescents and adults, and adults at high risk for severe RSV due to age or comorbidities. Symptom duration and hospital length of stay (LOS) were explored. Electronic database searches were performed following PRISMA guidelines. Studies captured RSV S&S across community and hospital settings. Clinicians and caregivers reported (n = 25 studies) nasal discharge/congestion, cough, shortness of breath, feeding abnormalities, and fever in ≥40% of children across studies and settings. Median hospital stays for children ranged from 2 days in the United States to 7.5 days in China. High-risk adults with RSV (n = 6 studies) commonly (≥40% of adults) reported cough, sputum, dyspnea, and fever/feverishness. Median length of hospital stay in adults ranged from 6 to 15 days across studies. Caregivers and clinicians reported similar RSV S&S in young children, including upper and lower respiratory and systemic symptoms. In high-risk and immunocompromised adults, the most frequent (in multiple publications) and commonly reported RSV S&S were primarily LRTI symptoms. RSV symptoms could last for weeks and are variable based on geography.

Responding to Higher-Than-Expected Infant Mortality Rates from Respiratory Syncytial Virus (RSV): Improving Treatment and Reporting Strategies

Respiratory syncytial virus (RSV) has a major role in respiratory infections in young infants around the world. However, substantial progress has been made in recent years in the field of RSV. A wide variety of observational studies and clinical trials published in the past decade provide a thorough idea of the health and economic burden of RSV disease in the developing world. In this review, we discuss the impact of RSV burden of disease, major gaps in disease estimations, and challenges in generating new therapeutic options and an immune response against the virus, and briefly describe next generation technologies that are being evaluated.

Respiratory Syncytial Virus Incidence and Severity in a Community-Based Prospective Cohort of Children Aged 0-14 Years

BACKGROUND

Respiratory syncytial virus (RSV) is a substantial source of severe illnesses including acute lower respiratory infections (ALRIs) like pneumonia. However, its burden in older children remains less well understood.

METHODS

Using a community-based prospective cohort, we assessed the burden of symptomatic reverse-transcription polymerase chain reaction-confirmed RSV among Nicaraguan children aged 0-14 years from 2011 to 2016. ALRI was defined as physician diagnosis of pneumonia, bronchiolitis, bronchitis, or bronchial hyperreactivity.

RESULTS

Between 2011 and 2016, 2575 children participated in the cohort. Of these, 630 (24.5%) had at least 1 episode of symptomatic RSV and 194 (7.5%) had multiple episodes. Subtype was identified in 571 (69.3%) episodes with 408 (71.5%) RSV-A, 157 (27.5%) RSV-B, and 6 (1%) positive for both. Children aged <2 years displayed the highest incidence of symptomatic RSV, with 269.3 cases per 1000 person-years (95% confidence interval [CI], 242.1-299.5). Beyond 2 years, incidence (95% CI) of symptomatic RSV decreased rapidly: 145.6 (129.9-163.1), 37.9 (31.9-45.0), and 19.3 (14.9-25.0) cases per 1000 person-years among children aged 2-4, 5-9, and 10-14 years, respectively. Incidence of RSV-associated ALRI was highest in children aged <2 years (85.95 per 1000 person-years [95% CI, 71.30-103.61]): 2.1, 9.5, and 17.3 times that of participants aged 2-4, 5-9, and 10-14 years, respectively. Children <2 years old were significantly more likely to have an RSV-associated hospitalization (P < .001).

CONCLUSIONS

There is a substantial burden of symptomatic and severe RSV in children. While older children did present with RSV, the rates of symptomatic and severe RSV decreased by as much as 95% beyond age 5.

Age-Dependent Clinical Characteristics of Acute Lower Respiratory Infections in Young Hospitalized Children with Respiratory Syncytial Virus Infection

Introduction

Human respiratory syncytial virus (HRSV) is the most common cause of acute lower respiratory infection (LRTI) in children. The main clinical manifestations are fever, cough, wheezing, and intercostal retractions. Its age-dependent clinical characteristics remain to be defined.

Objective

We investigated whether HRSV caused any age-related differences in clinical manifestations of LRTI.

Methods

We enrolled 130 hospitalized children with LRTI caused by HRSV. These were stratified into four age groups. The main signs and symptoms and rates thereof were compared across the four age groups.

Results

The incidence of pneumonia was the same in all four age groups. Patients in the 1-6 months old group experienced fever and the highest body temperature ≥ 38.5°C less frequently than patients in other age groups.The frequency of fever increased with age among the patients under 24 months old. Children over 12 months old experienced less wheezing, tachypnoea, hypoxia, and intercostal retractions than children in the 1-6 months old group.

Conclusion

HRSV caused age-related differences in clinical manifestations of LRTI. Reduced fever responses among patients 6 months old and younger during RSV infection does not implicate less severity, wheezing, tachypnoea, hypoxia, and intercostal retractions are the main clinical manifestations, Fever responses were enhanced with advancing age among children under 24 months old.

Comparison of infections with respiratory syncytial virus between children and adults: a multicenter surveillance from 2015 to 2019 in Beijing, China

The objective of this study is to investigate the epidemiological and clinical characteristics of the acute respiratory tract infections (ARTI) caused by respiratory syncytial virus (RSV) among the population of all age categories in Beijing, China. Outpatients and inpatients with ARTI were enrolled from 35 sentinel hospitals in Beijing between March 2015 and February 2019. They were interviewed and their medical records were collected using a standardized form. Their respiratory specimens were collected and tested for the nucleic acid of RSV. The RSV-positive specimens were further genotyped into RSV-A and RSV-B groups. A total of 29,923 cases were included in this study. RSV was detected in 623 (2%, 623/29923) patients, with 391 (62.8%) genotypd as RSV-A, 126 (20.2%) as RSV-B, and 106 (17.0%) untyped. The RSV epidemic season usually occurred between October and March covering approximately 90% of annual RSV infections. The RSV-infected children aged < 5 years accounted for 52.2% of the total RSV infections with cough and fever as the most common manifestations. The RSV-infected elderly adults aged ≥ 60 years have the second largest proportion (25.2%) with dyspnea and lymphocytopenia as the most common manifestations and showed an elevated rate of hospitalization, an increased rate of ICU admission, an extended length of hospital stay, and an elevated mortality compared to the RSV-infected children. The RSV infections aged ≥ 60 years old, as the second largest population of the total annual RSV infections, usually developed worse outcomes than children and should be taken seriously.

Respiratory syncytial virus among children hospitalized with severe acute respiratory infection in Kashmir, a temperate region in northern India

Background

Severe acute respiratory infections (SARI) are a leading cause of hospitalizations in children, especially due to viral pathogens. We studied the prevalence of respiratory viruses among children aged <5 years hospitalized with severe acute respiratory infections (SARI) in Kashmir, India.

Methods

We conducted a prospective observational study in two tertiary care hospitals from October 2013 to September 2014, systematically enrolling two children aged <5 years with SARI per day. We defined SARI as history of fever or measured fever (≥38°C) and cough with onset in the last 7 days requiring hospitalization for children aged 3-59 months and as physician-diagnosed acute lower respiratory infection for children aged <3 months. Trained study staff screened children within 24 hours of hospitalization for SARI and collected clinical data and nasopharyngeal swabs from enrolled participants. We tested for respiratory syncytial virus (RSV) A and B, influenza viruses, rhinoviruses (HRV)/enteroviruses, adenovirus (AdV), bocavirus (BoV), human metapneumovirus (hMPV) A and B, coronaviruses (OC43, NL65, C229E), and parainfluenza viruses (PIV) 1, 2, 3 and 4 using standardized duplex real-time polymerase chain reaction.

Results

Among 4548 respiratory illness admissions screened from October 2013 to September 2014, 1026 met the SARI case definition, and 412 were enrolled (ages = 5 days to 58 months; median = 12 months). Among enrolees, 256 (62%) were positive for any virus; RSV was the most commonly detected (n = 118, 29%) followed by HRV/enteroviruses (n = 88, 21%), PIVs (n = 31, 8%), influenza viruses (n = 18, 4%), BoV (n = 15, 4%), coronaviruses (n = 16, 4%), AdV (n = 14, 3%), and hMPV (n = 9, 2%). Fifty-four children had evidence of virus co-detection. Influenza-associated SARI was more common among children aged 1-5 years (14/18, 78%) while most RSV detections occurred in children <12 months (83/118, 70%). Of the RSV viruses typed (n = 116), the majority were type B (94, 80%). Phylogenetic analysis of G gene of RSV showed circulation of the BA9 genotype with 60bp nucleotide duplication.

Conclusions

Respiratory viruses, especially RSV, contributed to a substantial proportion of SARI hospitalizations among children <5 years in north India. These data can help guide clinicians on appropriate treatment and prevention strategies.

Respiratory syncytial virus-associated hospitalisation in children aged ≤5 years: a scoping review of literature from 2009 to 2021

Introduction

Following the easing of COVID-19 restrictions in many countries, a surge in respiratory syncytial virus (RSV) hospitalisations was reported, surpassing yearly trends pre-pandemic. The changes to RSV epidemiology may have unforeseen effects on healthcare systems and populations globally, adding to the burden generated during the pandemic and placing increased demand on resources. Here we aim to identify recent global trends of RSV hospitalisation amongst children aged ≤5 years, to help inform policy makers in the planning of preventative interventions.

Methods

We conducted a scoping review of published literature between January 2009 and May 2021. Using keywords “Hospital admissions, Respiratory syncytial virus, RSV, Bronchiolitis, Children” we located studies using Medline, EMCARE, CINAHL and HMIC. Studies were eligible if they reported on trends/data for RSV hospitalisation amongst children aged ≤5 years. The articles were reviewed by two independent reviewers.

Findings

We assessed 3310 abstracts, reviewed 70 studies and included 56 studies in the final review. Findings were categorised into themes. The review highlighted that, although RSV incidence has been steadily increasing since 2009, the number of reported RSV hospitalisations decreased during lockdown. The highest numbers of hospitalisations were reported in children <1 year of age, particularly 0–2-month-old infants. Globally, RSV hospitalisations tend to peak in the winter months; however, since COVID-19 restrictions have eased, countries are reporting incidence peaks at different times, in contrast to the trends of previous years.

Conclusion

With greater physical interactions due to the relaxation of COVID-19 restriction measures, RSV-related hospitalisations can be seen to increase amongst children aged ≤5 years, possibly surpassing the numbers reported in previous RSV seasons.

With #COVID19 restriction measures being eased globally, #RSV-related hospitalisation among children will increase, possibly surpassing pre-pandemic levelshttps://bit.ly/35lg4Iv

Hospitalization rate of respiratory syncytial virus-associated acute lower respiratory infection among young children in Suzhou, China, 2010-2014

Background

There is a limited amount of data in China on the disease burden of respiratory syncytial virus‐ (RSV) associated acute lower respiratory infection (ALRI) among young children. This study aimed to estimate the hospitalization rate of RSV‐associated ALRI (RSV‐ALRI) among children aged 0–59 months in Suzhou, China.

Methods

All cases from children hospitalized with ALRI who were aged 0–59 months in Suzhou University Affiliated Children's Hospital during January 2010 to December 2014 were retrospectively identified. Detailed diagnosis and treatment data were collected by reviewing each individual's medical chart. In accordance with the World Health Organization (WHO) influenza disease burden estimation, the hospitalization rate of RSV‐ALRI among children aged 0–59 months in Suzhou, China, was then estimated.

Results

Out of the 28,209 ALRI cases, 19,317 (68.5%) were tested for RSV, of which the RSV positive proportion was 21.3% (4107/19,317). The average hospitalization rate of RSV‐ALRI for children aged 0–59 months was 14 (95% confidence interval [CI]:14–14)/1000 children years, and that for children aged 0–5, 6–11, 12–23, and 24–59 months were 70 (95% CI: 67–73), 31 (95% CI: 29–33), 11 (95% CI: 10–12), and 3 (95% CI: 3–3)/1000 children years, respectively.

Conclusion

A considerable degree of RSV‐ALRI hospitalization exists among children aged 0–59 months, particularly in those under 1 year of age. Therefore, an effective monoclonal antibody or vaccine is urgently needed to address the substantial hospitalization burden of RSV infection.

World Health Organization Influenza-Like Illness Underestimates the Burden of Respiratory Syncytial Virus Infection in Community-Dwelling Older Adults

Background

Respiratory syncytial virus (RSV) surveillance is heavily dependent on the influenza-like illness (ILI) case definition from the World Health Organization (WHO). Because ILI includes fever in its syndromic case definition, its ability to accurately identify acute respiratory tract infections (ARTI) caused by RSV in older adults is uncertain.

Methods

The accuracy of the WHO ILI and a modified ILI (requiring only self-reported fever) case definitions in identifying patients with PCR-confirmed RSV-ARTI was evaluated in community-dwelling older adults (≥60 years) from the prospective European RESCEU cohort study.

Results

Among 1040 participants, 750 ARTI episodes were analyzed including 36 confirmed RSV-ARTI. Due to a general lack of fever, sensitivity for RSV-ARTI was 33% for modified ILI and 11% for ILI. The area under the curve for both ILI definitions was 0.52 indicating poor discrimination for RSV. RSV-ARTI could not be distinguished from all other ARTI based on clinical symptoms.

Conclusions

The use of ILI underestimated the occurrence of RSV-ARTI in community-dwelling older adults up to 9-fold (11% sensitivity). Because worldwide RSV surveillance depends largely on ILI, there is an urgent need for a better approach to measure the occurrence of RSV disease and the impact of future RSV vaccine introduction.

Clinical Trials Registration. NCT03621930.

The Burden of Respiratory Viruses and Their Prevalence in Different Geographical Regions of India: 1970-2020

As per the 2019 report of the National Health Portal of India, 41,996,260 cases and 3,740 deaths from respiratory infections were recorded across India in 2018. India contributes to 18% of the global population, with severe acute respiratory infection (SARI) as one of the prominent causes of mortality in children >5 years of age. Measures in terms of the diagnosis and surveillance of respiratory infections are taken up globally to discover their circulating types, detect outbreaks, and estimate the disease burden. Similarly, the purpose of this review was to determine the prevalence of respiratory infections in various regions of India through published reports. Understanding the pattern and prevalence of various viral entities responsible for infections and outbreaks can help in designing better strategies to combat the problem. The associated pathogens comprise respiratory syncytial virus (RSV), rhinovirus, influenza virus, parainfluenza virus, adenovirus, etc. Identification of these respiratory viruses was not given high priority until now, but the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has sensitized our system to be alert about the burden of existing infections and to have proper checks for emerging ones. Most of the studies reported to date have worked on the influenza virus as a priority. However, the data describing the prevalence of other respiratory viruses with their seasonal pattern have significant epidemiological value. A comprehensive literature search was done to gather data from all geographical regions of India comprising all states of India from 1970 to 2020. The same has been compared with the global scenario and is being presented here.

Disease Burden Due to Respiratory Syncytial Virus in Indian Pediatric Population: A Literature Review

Respiratory syncytial virus (RSV) is one of the leading causes of lower respiratory tract infections in young children. Globally, there is huge disease burden, high treatment cost, and health impact beyond acute episodes due to RSV which necessitate development and implementation of preventive strategies for the control of RSV infection. The disease burden due to RSV in pediatric population across India is still not clearly understood so this literature review was therefore conducted to gather data on disease burden due to RSV in Indian pediatric population. Systematic literature search was performed using PubMed and Google search with different medical subject headings from 2007 to 2020. Studies performed in Indian pediatric population were selected for review. Literature review revealed that in India, epidemiology of RSV infection is well documented in young children (0-5 years) as compared to children from other age groups. The rates of RSV detection in various studies conducted in younger children (0-5 years) vary from 2.1% to 62.4% in India which is higher as compared to children from other age groups. In India, RSV mainly peaks around rainy to early winter season, that is, during months of June through October while smaller peak was noted during December, January, and February. In 2020, higher RSV-associated disease burden was reported among children (<5 years) in low-income and lower-middle-income countries. Considering significant disease burden due to RSV in young Indian children, availability of RSV vaccine would be crucial to prevent RSV infections in children and its spread in the community.

Recommendations for respiratory syncytial virus surveillance at national level

Respiratory syncytial virus (RSV) is a common cause of acute lower respiratory tract infections and hospitalisations among young children and is globally responsible for many deaths in young children, especially in infants aged <6 months. Furthermore, RSV is a common cause of severe respiratory disease and hospitalisation among older adults. The development of new candidate vaccines and monoclonal antibodies highlights the need for reliable surveillance of RSV. In the European Union (EU), no up-to-date general recommendations on RSV surveillance are currently available. Based on outcomes of a workshop with 29 European experts in the field of RSV virology, epidemiology and public health, we provide recommendations for developing a feasible and sustainable national surveillance strategy for RSV that will enable harmonisation and data comparison at the European level. We discuss three surveillance components: active sentinel community surveillance, active sentinel hospital surveillance and passive laboratory surveillance, using the EU acute respiratory infection and World Health Organization (WHO) extended severe acute respiratory infection case definitions. Furthermore, we recommend the use of quantitative reverse transcriptase PCR-based assays as the standard detection method for RSV and virus genetic characterisation, if possible, to monitor genetic evolution. These guidelines provide a basis for good quality, feasible and affordable surveillance of RSV. Harmonisation of surveillance standards at the European and global level will contribute to the wider availability of national level RSV surveillance data for regional and global analysis, and for estimation of RSV burden and the impact of future immunisation programmes.

Recommendations for developing a feasible and sustainable national surveillance strategy for respiratory syncytial virus that will enable harmonisation and data comparison at the European level.https://bit.ly/3rWUOOI

Viral Etiology, Clinical Features and Antibiotic Use in Children <5 Years of Age in the Gambia Presenting With Influenza-like Illness

BACKGROUND

Knowledge regarding the prevalence, clinical features and etiology of pediatric influenza-like illness (ILI) remains limited in African settings. Furthermore, it is likely that many children presenting with ILI receive antibiotics unnecessarily. More data are required to develop antimicrobial stewardship practice and guide effective vaccine strategies. We undertook a 1-year prospective study of ILI in the Gambia.

METHODS

Children <5 years of age presenting with ILI from March 2018 to March 2019 were recruited. Clinical and antibiotic prescribing data were collected. Nasopharyngeal swabs were collected and analyzed for 12 respiratory viruses using a multiplex polymerase chain reaction.

RESULTS

From a total of 735 ILI episodes, 530 (72.1%) nasopharyngeal swabs were positive for ≥1 virus. Of these, 36.7% were positive for rhinovirus, 14.7% for respiratory syncytial virus, 8.4% for influenza and 7.2% for human metapneumovirus. Compared with children <6 months of age, influenza was more common in 6- to 23-month-old children [odd ratio (OR): 5.68; 95% confidence interval (CI): 1.72-18.76; P = 0.004]. Respiratory syncytial virus and human metapneumovirus were associated with low peripheral oxygen saturations (OR: 2.13; 95% CI: 1.23-3.69; P = 0.007; and OR: 2.44; 95% CI: 1.13-5.27; P = 0.023, respectively). Antibiotics were prescribed in 78.3% of all ILI cases.

CONCLUSIONS

A broad range of viruses are responsible for pediatric ILI in the Gambia. Refined treatment guidelines, improved diagnostic capacity and vaccines to prevent respiratory viruses will all play a role in reducing antimicrobial use for these cases.

Performance of surveillance case definitions for respiratory syncytial virus infections through the sentinel influenza surveillance system, Portugal, 2010 to 2018

BackgroundWell-established influenza surveillance systems (ISS) can be used for respiratory syncytial virus (RSV) surveillance. In Portugal, RSV cases are detected through the ISS using the European Union (EU) influenza-like illness (ILI) case definition.AimTo investigate clinical predictors for RSV infection and how three case definitions (EU ILI, a modified EU acute respiratory infection, and one respiratory symptom) performed in detecting RSV infections in Portugal.MethodsThis observational retrospective study used epidemiological and laboratory surveillance data (October 2010-May 2018). Associations between clinical characteristics and RSV detection were analysed using logistic regression. Accuracy of case definitions was assessed through sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). A 0.05 significance level was accepted.ResultsThe study involved 6,523 persons, including 190 (2.9%) RSV cases. Among 183 cases with age information, RSV infection was significantly more frequent among individuals < 5 years (n = 23; 12.6%) and ≥ 65 years (n = 45; 24.6%) compared with other age groups (p < 0.0001). Cough (odds ratio (OR): 2.4; 95% confidence interval (CI): 1.2-6.5) was the best RSV-infection predictor considering all age groups, while shortness of breath was particularly associated with RSV-positivity among ≤ 14 year olds (OR: 6.7; 95% CI: 2.6-17.4 for 0-4 year olds and OR: 6.7; 95% CI: 1.5-28.8 for 5-14 year olds). Systemic symptoms were significantly associated with RSV-negative and influenza-positive cases. None of the case definitions were suitable to detect RSV infections (AUC = 0.51).ConclusionTo avoid underestimating the RSV disease burden, RSV surveillance within the Portuguese sentinel ISS would require a more sensitive case definition than ILI and, even a different case definition according to age.

Assessing the Incidence of Symptomatic Respiratory Syncytial Virus Illness Within a Prospective Birth Cohort in Managua, Nicaragua

BACKGROUND

Respiratory syncytial virus (RSV) causes substantial morbidity and mortality among children worldwide, commonly through acute lower respiratory tract infections (ALRI). To assess the incidence rate of symptomatic RSV illness among young children, we conducted a prospective birth cohort study following children from 0-2 years of age in Managua, Nicaragua.

METHODS

Children meeting the testing criteria (fever, history of fever, or severe respiratory symptoms [apnea, stridor, nasal flaring, wheezing, chest indrawing, and/or central cyanosis]) were tested for RSV infections using real-time reverse transcriptase-polymerase chain reaction. An acute lower respiratory infection was defined as a diagnosis of pneumonia, bronchiolitis, bronchitis, or bronchial hyperreactivity. The incidence rate was calculated, and 95% confidence intervals were estimated using a Poisson distribution.

RESULTS

A total of 833 children participated in the cohort: 289 (34.7%) had at least 1 episode of laboratory-confirmed RSV, and 156 (18.7%) of had an episode of RSV-associated ALRI (RSV-ALRI). The incidence rate of symptomatic RSV was 248.1 cases per 1000 person-years (95% confidence interval [CI] 223.2-275.7). While infants aged 6-11 months had the highest incidence of symptomatic RSV (361.3/1000 person-years, 95% CI 304.4-428.8), infants <3 months had the highest incidence of severe RSV (RSV-associated hospitalizations and/or severe ALRI). RSV was also associated with 25.0-37.5% of deaths from medical causes (n = 8).

CONCLUSIONS

A substantial burden of RSV exists among children aged <2 years in Nicaraguan communities. RSV was also a leading cause of infant mortality among study participants. The development and implementation of effective RSV prevention and treatment measures represent an opportunity to substantially reduce severe illness and death among children worldwide.

Evaluating the diagnostic accuracy of the WHO Severe Acute Respiratory Infection (SARI) criteria in Middle Eastern children under two years over three respiratory seasons

OBJECTIVE

The World Health Organization created the Severe Acute Respiratory Infection (SARI) criteria in 2011 to monitor influenza (flu)-related hospitalization. Many studies have since used the SARI case definition as inclusion criteria for surveillance studies. We sought to determine the sensitivity, specificity, positive predictive value, and negative predictive value of the SARI criteria for detecting ten different respiratory viruses in a Middle Eastern pediatric cohort.

MATERIALS AND METHODS

The data for this study comes from a prospective acute respiratory surveillance study of hospitalized children <2 years in Amman, Jordan from March 16, 2010 to March 31, 2013. Participants were recruited if they had a fever and/or respiratory symptoms. Nasal and throat swabs were obtained and tested by real-time RT-PCR for eleven viruses. Subjects meeting SARI criteria were determined post-hoc. Sensitivity, specificity, positive predictive value, and negative predictive value of the SARI case definition for detecting ten different viruses were calculated and results were stratified by age.

RESULTS

Of the 3,175 patients enrolled, 3,164 were eligible for this study, with a median age of 3.5 months, 60.4% male, and 82% virus-positive (44% RSV and 3.8% flu). The sensitivity and specificity of the SARI criteria for detecting virus-positive patients were 44% and 77.9%, respectively. Sensitivity of SARI criteria for any virus was lowest in children <3 months at 22.4%. Removing fever as a criterion improved the sensitivity by 65.3% for detecting RSV in children <3 months; whereas when cough was removed, the sensitivity improved by 45.5% for detecting flu in same age group.

CONCLUSIONS

The SARI criteria have poor sensitivity for detecting RSV, flu, and other respiratory viruses-particularly in children <3 months. Researchers and policy makers should use caution if using the criteria to estimate burden of disease in children.

Respiratory Syncytial Virus Seasonality, Beijing, China, 2007-2015

During July 2007-June 2015, we enrolled 4,225 hospitalized children with pneumonia in a study to determine the seasonality of respiratory syncytial virus (RSV) infection in Beijing, China. We defined season as the period during which >10% of total PCRs performed each week were RSV positive. We identified 8 distinctive RSV seasons. On average, the season onset occurred at week 41 (mid-October) and lasted 33 weeks, through week 20 of the next year (mid-May); 97% of all RSV-positive cases occurred during the season. RSV seasons occurred 3-5 weeks earlier and lasted ≈6 weeks longer in RSV subgroup A-dominant years than in RSV subgroup B-dominant years. Our analysis indicates that monitoring such RSV subgroup shifts might provide better estimates for the onset of RSV transmission. PCR-based tests could be a flexible or complementary way of determining RSV seasonality in locations where RSV surveillance is less well-established, such as local hospitals throughout China.

Assessment and Validation of Syndromic Case Definitions for Respiratory Syncytial Virus Infections in Young Infants: A Latent Class Analysis

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of pediatric morbidity and mortality worldwide. Standardized case definitions that are applicable to variety of populations are critical for robust surveillance systems to guide decision-making regarding RSV control strategies including vaccine evaluation. Limited data exist on performance of RSV syndromic case definitions among young infants or in high-resource settings.

OBJECTIVE

The purpose of this study was to evaluate existing and potential syndromic case definitions for RSV among young infants in an urban, high-income setting using latent class analyses (LCA).

METHODS

We used data collected on infants <6 months of age tested for RSV as part of routine clinical care at Children's Healthcare of Atlanta between January 2010 and December 2015. We computed the sensitivity, specificity, positive and negative predictive values of clinical features, existing syndromic case definitions used by the World Health Organization (WHO) and alternative definitions we constructed using LCA to detect RSV infection.

RESULTS

Among 565 infants tested for RSV, 161 (28.5%) had laboratory-confirmed RSV infection. Among all case definitions evaluated, the definition developed through LCA (cough plus shortness of breath plus coryza plus wheeze plus poor feeding plus chest in-drawing) was the most specific (95.8%, 95% CI 93.8-97.8) and had the highest positive predictive value (51.4%, 95% CI, 34.9-68.0). WHO-acute respiratory infection (cough or sore throat or shortness of breath or coryza, plus a clinician's judgment that illness is due to infection) was the most sensitive (98.1%, 95% CI, 96.1-100.0; negative predictive value 96.3%, 95% CI 92.2-100.0).

CONCLUSIONS

The WHO acute respiratory infection definition could be useful for initial screening for RSV among infants <6 months, whereas our alternative syndromic case definition may serve as the strongest confirmatory case definition in the same population. Appropriate case definitions will vary depending on the content and setting in which they are utilized.

Clinical characteristics, predictors, and performance of case definition-Interim results from the WHO global respiratory syncytial virus surveillance pilot

Background

The lack of a uniform surveillance case definition poses a challenge to characterize the epidemiology, clinical features, and disease burden of the respiratory syncytial virus (RSV). Global standards for RSV surveillance will inform immunization policy when RSV vaccines become available.

Methods

The WHO RSV surveillance pilot leverages the capacities of the Global Influenza Surveillance and Response System (GISRS). Hospitalized and non‐hospitalized medically attended patients of any age were tested for RSV using standardized molecular diagnostics throughout the year in fourteen countries. An extended severe acute respiratory infection (extended SARI) or an acute respiratory infection (ARI) case definition was used that did not require fever as a criterion.

Results

Amongst 21 221 patients tested for RSV between January 2017 and September 2018, 15 428 (73%) were hospital admissions. Amongst hospitalized RSV‐positive patients, 50% were aged <6 months and 88% <2 years. The percentage of patients testing positive for RSV was 37% in children <6 months and 25% in those aged 6 months to 2 years. Patients with fever were less likely to be RSV positive compared to those without fever (OR 0.74; 95% CI: 0.63‐0.86). For infants <6 months, 29% of RSV ARI cases did not have fever.

Conclusion

Requiring fever in a case definition for RSV lowers the sensitivity to detect cases in young children. Countries should consider ways to leverage the GISRS platform to implement RSV surveillance with an augmented case definition amongst the young pediatric population.

Performance of Surveillance Case Definitions in Detecting Respiratory Syncytial Virus Infection Among Young Children Hospitalized With Severe Respiratory Illness-South Africa, 2009-2014

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection (ALRTI) in young children, but data on surveillance case definition performance in estimating burdens have been limited.

METHODS

We enrolled children aged <5 years hospitalized for ALRTI (or neonatal sepsis in young infants) through active prospective surveillance at 5 sentinel hospitals in South Africa and collected nasopharyngeal aspirates from them for RSV molecular diagnostic testing between 2009 and 2014. Clinical data were used to characterize RSV disease and retrospectively evaluate the performance of respiratory illness case definitions (including the World Health Organization definition for severe acute respiratory infection [SARI]) in identifying hospitalized children with laboratory-confirmed RSV according to age group (<3, 3-5, 6-11, 12-23, and 24-59 months).

RESULTS

Of 9969 hospitalized children, 2723 (27%) tested positive for RSV. Signs and symptoms in RSV-positive children varied according to age; fever was less likely to occur in children aged <3 months (57%; odds ratio [OR], 0.8 [95% CI, 0.7-0.9]) but more likely in those aged ≥12 months (82%; OR, 1.7-1.9) than RSV-negative children. The sensitivity (range, 55%-81%) and specificity (range, 27%-54%) of the SARI case definition to identify hospitalized RSV-positive children varied according to age; the lowest sensitivity was for infants aged <6 months. Using SARI as the case definition would have missed 36% of RSV-positive children aged <5 years and 49% of those aged <3 months; removing the fever requirement from the definition recovered most missed cases.

CONCLUSION

Including fever in the SARI case definition lowers the sensitivity for RSV case detection among young children hospitalized with an ALRTI and likely underestimates its burden.

Leveraging the Global Influenza Surveillance and Response System for global respiratory syncytial virus surveillance-opportunities and challenges

BACKGROUND

Respiratory syncytial virus (RSV)-associated acute lower respiratory infection is a common cause for hospitalization and hospital deaths in young children globally. There is urgent need to generate evidence to inform immunization policies when RSV vaccines become available. The WHO piloted a RSV surveillance strategy that leverages the existing capacities of the Global Influenza Surveillance and Response System (GISRS) to better understand RSV seasonality, high-risk groups, validate case definitions, and develop laboratory and surveillance standards for RSV.

METHODS

The RSV sentinel surveillance strategy was piloted in 14 countries. Patients across all age groups presenting to sentinel hospitals and clinics were screened all year-round using extended severe acute respiratory infection (SARI) and acute respiratory infection (ARI) case definitions for hospital and primary care settings, respectively. Respiratory specimens were tested for RSV at the National Influenza Centre (NIC) using standardized molecular diagnostics that had been validated by an External Quality Assurance program. The WHO FluMart data platform was adapted to receive case-based RSV data and visualize interactive visualization outputs.

RESULTS

Laboratory standards for detecting RSV by RT-PCR were developed. A review assessed the feasibility and the low incremental costs for RSV surveillance. Several challenges were addressed related to case definitions, sampling strategies, the need to focus surveillance on young children, and the data required for burden estimation.

CONCLUSIONS

There was no evidence of any significant adverse impact on the functioning of GISRS which is primarily intended for virologic and epidemiological surveillance of influenza.

Respiratory syncytial virus infections in India: Epidemiology and need for vaccine

Respiratory syncytial virus (RSV) has been identified as a leading cause of lower respiratory tract infections in young children and elderly. It is an enveloped negative-sense RNA virus belonging to Genus Orthopneumovirus. The clinical features of RSV infection range from mild upper-respiratory-tract illnesses or otitis media to severe lower-respiratory-tract illnesses. Current estimates show that about 33.1 million episodes of RSV-acute lower respiratory infection (ALRI) occurred in young children in 2015, of these majority that is, about 30 million RSV-ALRI episodes occurred in low-middle-income countries. In India, the rates of RSV detection in various hospital- and community-based studies mostly done in children vary from 5% to 54% and from 8% to 15%, respectively. Globally, RSV epidemics start in the South moving to the North. In India, RSV mainly peaks in winter in North India and some correlation with low temperature has been observed. Different genotypes of Group A (GA2, GA5, NA1 and ON1) and Group B (GB2, SAB4 and BA) have been described from India. The burden of RSV globally has kept it a high priority for vaccine development. After nearly 50 years of attempts, there is still no licensed vaccine and challenges to obtain a safe and effective vaccine is still facing the scientific community. The data in this review have been extracted from PubMed using the keywords RSV and Epidemiology and India. The data have been synthesised by the authors.

Seroepidemiology of respiratory syncytial virus in western India with special reference to appropriate age for infant vaccination

Respiratory syncytial virus (RSV) causes significant infant mortality worldwide and a vaccine may be available soon. This study determined age-stratified anti-RSV antibody positivity (enzyme-linked immunosorbent assay [ELISA]) at Pune, India (cord blood-85 years). Antibody positivity declined from 100% at birth to 71.3% (3 months), and 0.7% (6 months). A significant rise was noted at 15 months (16%), 16 to 24 months (64.5%) and 4 years (95.2%) with concomitant IgM-anti-RSV positivity indicative of recent infection. Antibody decline was higher in infants born preterm than full-term. Across subsequent age groups including the elderly, antibody positivity was similar and comparable, suggestive of repeated exposure to the virus. Early protection/vaccination is essential for the infant population.

Prevalence of respiratory syncytial virus infection among children hospitalized with acute lower respiratory tract infections in Southern India

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory infections among children.

AIM

To investigate the proportion of RSV and non-RSV respiratory viral infections among hospitalized children ≤ 5 years.

METHODS

Hospitalized children aged < 5 years, with a diagnosis of acute lower respiratory infections (ALRI), admitted between August 2011-August 2013, were included. Cases were defined as laboratory-confirmed RSV and non-RSV respiratory viruses by direct fluorescence assay from the nasopharyngeal wash.

RESULTS

Of 383 1-59 mo old children hospitalized with an acute lower respiratory infection, 33.9% (130/383) had evidence of viral infection, and RSV was detected in 24.5% (94/383). Co-infections with RSV and other respiratory viruses (influenza A or B, adenovirus, para influenza 1, 2 or 3) were seen in children 5.5% (21/383). Over 90% of the RSV-positive children were under 2 years of age. RSV was detected throughout the year with peaks seen after the monsoon season. Children hospitalized with RSV infection were more likely to have been exposed to a shorter duration of breastfeeding of less than 3 mo. RSV positive children had a shorter hospital stay, although there were significant complications requiring intensive care. Use of antibiotics was high among those with RSV and non-RSV viral infections.

CONCLUSION

Our study provides evidence of a high proportion of RSV and other virus-associated ALRI among hospitalized children in India. RSV infection was associated with fewer days of hospital stay compared to other causes of lower respiratory infections. A high level of antibiotic use was seen among all respiratory virus-associated hospitalizations. These results suggest the need for implementing routine diagnostics for respiratory pathogens in order to minimize the use of unnecessary antibiotics and plan prevention strategies among pediatric populations.

Assessment and Validation of Syndromic Case Definitions for Respiratory Syncytial Virus Testing in a Low Resource Population

Standardized case definitions are needed in decision-making regarding respiratory syncytial virus control strategies, including vaccine evaluation. A syndromic case definition comprising of "wheeze or apnea or cyanosis" could be useful for community-based surveillance of moderate respiratory syncytial virus infection among young infants particularly in resource-limited settings. However, this definition showed modest specificity (29.2%-49.6%), indicating that community-based surveillance may need augmentation with other data.

Predictors and incidence of hospitalization due to respiratory syncytial virus (RSV)-associated lower respiratory tract infection (LRTI) in non-prophylaxed moderate-to-late preterm infants in Bosnia and Herzegovina

Prematurity is a risk factor for respiratory syncytial virus (RSV)-associated lower respiratory tract infections (LRTIs), due to immature humoral and cell-mediated immune system in preterm newborns, as well as their incomplete lung development. Palivizumab, a humanized monoclonal antibody against the F glycoprotein of RSV, is licensed for the prevention of severe RSV LRTI in children at high risk for the disease. This study is a part of a larger observational, retrospective-prospective epidemiological study (PONI) conducted at 72 sites across 23 countries in the northern temperate zone. The aim of our non-interventional study was to identify common predictors and factors associated with RSV LRTI hospitalization in non-prophylaxed, moderate-to-late preterm infants, born between 33 weeks and 0 days and 35 weeks and 6 days of gestation, and less than 6 months prior to or during the RSV season in Bosnia and Herzegovina (B&H). A total of 160 moderate-to-late preterm infants were included from four sites in B&H (Sarajevo, Tuzla, Mostar, and Banja Luka). We identified several significant intrinsic and extrinsic factors to be associated with the risk of RSV LRTI hospitalization in the preterm infants, including: comorbidities after birth, shorter hospital stay, admission to NICU/PICU while in the maternity ward, household smoking, low maternal age, breast feeding, number of family members, and history of family/paternal atopy. Overall, our results indicated that the risk of RSV LRTI in preterm newborns can be associated with different environmental and social/cultural factors, and further research is needed to comprehensively evaluate these associations.

Severe outcomes associated with respiratory viruses in newborns and infants: a prospective viral surveillance study in Jordan

OBJECTIVE

To assess virus-specific hospitalisation rates, risk factors for illness severity and seasonal trends in children hospitalised with acute respiratory infections (ARI).

DESIGN

Prospective cohort study.

SETTING

A government hospital serving low-income and middle-income population in Amman, Jordan.

PARTICIPANTS

Children under 2 years of age hospitalised with fever and/or respiratory symptoms (n=3168) from 16 March 2010 to 31 March 2013. Children with chemotherapy-associated neutropenia and newborns who had never been discharged after birth were excluded from the study.

OUTCOME MEASURES

Hospitalisation rates and markers of illness severity: admission to intensive care unit (ICU), mechanical ventilation (MV), oxygen therapy, length of stay (LOS) and death.

RESULTS

Of the 3168 subjects, 2581 (82%) had at least one respiratory virus detected, with respiratory syncytial virus (RSV) being the most predominant pathogen isolated. During admission, 1013 (32%) received oxygen therapy, 284 (9%) were admitted to ICU, 111 (4%) were placed on MV and 31 (1%) children died. Oxygen therapy was higher in RSV-only subjects compared with human rhinovirus-only (42%vs29%, p<0.001), adenovirus-only (42%vs21%, p<0.001) and human parainfluenza virus-only (42%vs23%, p<0.001) subjects. The presence of an underlying medical condition was associated with oxygen therapy (adjusted OR (aOR) 1.95, 95% CI 1.49 to 2.56), ICU admission (aOR 2.51, 95% CI 1.71 to 3.68), MV (aOR 1.91, 95% CI 1.11 to 3.28) and longer LOS (aOR1.71, 95% CI 1.37 to 2.13). Similarly, younger age was associated with oxygen therapy (0.23, 95% CI 0.17 to 0.31), ICU admission (aOR 0.47, 95% CI 0.30 to 0.74), MV (0.28, 95% CI 0.15 to 0.53) and longer LOS (aOR 0.47, 95% CI 0.38 to 0.59). Pneumonia was strongly associated with longer LOS (aOR 2.07, 95% CI 1.65 to 2.60), oxygen therapy (aOR 2.94, 95% CI 2.22 to 3.89), ICU admission (aOR 3.12, 95% CI 2.16 to 4.50) and MV (aOR 3.33, 95% CI 1.85 to 6.00). Virus-specific hospitalisation rates ranged from 0.5 to 10.5 per 1000 children.

CONCLUSION

Respiratory viruses are associated with severe illness in Jordanian children hospitalised with ARI. Prevention strategies such as extended breast feeding, increased access to palivizumab and RSV vaccine development could help decrease hospitalisation rates and illness severity, particularly in young children with underlying medical conditions.

Viral etiologies of influenza-like illness and severe acute respiratory infections in Thailand

Background

Information on the burden, characteristics and seasonality of non‐influenza respiratory viruses is limited in tropical countries.

Objectives

Describe the epidemiology of selected non‐influenza respiratory viruses in Thailand between June 2010 and May 2014 using a sentinel surveillance platform established for influenza.

Methods

Patients with influenza‐like illness (ILI; history of fever or documented temperature ≥38°C, cough, not requiring hospitalization) or severe acute respiratory infection (SARI; history of fever or documented temperature ≥38°C, cough, onset <10 days, requiring hospitalization) were enrolled from 10 sites. Throat swabs were tested for influenza viruses, respiratory syncytial virus (RSV), metapneumovirus (MPV), parainfluenza viruses (PIV) 1‐3, and adenoviruses by polymerase chain reaction (PCR) or real‐time reverse transcriptase‐PCR.

Results

We screened 15 369 persons with acute respiratory infections and enrolled 8106 cases of ILI (5069 cases <15 years old) and 1754 cases of SARI (1404 cases <15 years old). Among ILI cases <15 years old, influenza viruses (1173, 23%), RSV (447, 9%), and adenoviruses (430, 8%) were the most frequently identified respiratory viruses tested, while for SARI cases <15 years old, RSV (196, 14%) influenza (157, 11%) and adenoviruses (90, 6%) were the most common. The RSV season significantly overlapped the larger influenza season from July to November in Thailand.

Conclusions

The global expansion of influenza sentinel surveillance provides an opportunity to gather information on the characteristics of cases positive for non‐influenza respiratory viruses, particularly seasonality, although adjustments to case definitions may be required.

Respiratory syncytial virus is an "opportunistic" killer

Respiratory syncytial virus (RSV), responsible for more than three million yearly hospitalizations and up to 118 000 deaths in children under 5 years, is the leading pulmonary cause of death for this age group that lacks a licensed vaccine. Ninety-nine percent of deaths due to the virus occur in developing countries. In-hospital RSV fatalities affect previously healthy term infants in association with bacterial sepsis, clinically significant pneumothoraxes and, to a lesser extent, comorbid conditions. Community deaths affect low-income children from socially vulnerable families and appear to be as frequent as inpatient fatalities. In industrialized countries, RSV deaths occur almost exclusively in children with premorbid conditions. In a sense, RSV is an "opportunistic" killer. It needs a synergistic premorbid, medical practice-related, infectious, or social co-factor to cause a fatal outcome. But while the complex problems associated with these co-factors await solutions, candidate vaccines, long-lived monoclonal antibodies and antivirals against RSV are under clinical evaluation. It seems reasonable to predict that the landscape of RSV infections will look different in the next decade.

Identifying Gaps in Respiratory Syncytial Virus Disease Epidemiology in the United States Prior to the Introduction of Vaccines

Respiratory syncytial virus (RSV) causes lower respiratory tract illness frequently. No effective antivirals or vaccines for RSV are approved for use in the United States; however, there are at least 50 vaccines and monoclonal antibody products in development, with those targeting older adults and pregnant women (to protect young infants) in phase 2 and 3 clinical trials. Unanswered questions regarding RSV epidemiology need to be identified and addressed prior to RSV vaccine introduction to guide the measurement of impact and future recommendations. The Centers for Disease Control and Prevention (CDC) convened a technical consultation to gather input from external subject matter experts on their individual perspectives regarding evidence gaps in current RSV epidemiology in the United States, potential studies and surveillance platforms needed to fill these gaps, and prioritizing efforts. Participants articulated their individual views, and CDC staff synthesized individuals' input into this report.

Risk factors of respiratory syncytial virus infection among pediatric influenza-like illness and severe acute respiratory infections in Suzhou, China

The characteristics and risk factors of respiratory syncytial virus (RSV) infection among children has not yet been fully understood. To address the characteristics of RSV-associated illness and risk factors of RSV infection among children under 5 years of age in Suzhou, China. From April 2011 to March 2014, we conducted a prospective surveillance among children in Suzhou, China. Nasal or throat swabs were collected from outpatients with influenza-like illness (ILI) and inpatients with severe acute respiratory infections (SARI). RSV was detected by reverse-transcriptase polymerase chain reaction and direct fluorescent antibody assay for children with ILI and SARI, respectively. Multivariable logistic-regression models were constructed to explore risk factors and symptoms of RSV infection. Of 3267 ILI and 1838 SARI children enrolled in the study, 192 (5.9%) and 287 (15.6%) tested positive for RSV, respectively. Among ILI patients, children with RSV infections visited clinics more often (P = 0.005) and had longer duration of fever (P = 0.032) than those without RSV infection. All RSV-positive children had an increased risk of having cough (OR = 2.9), rhinorrhea (OR = 1.6), breathing difficulty (OR = 3.4), wheezing (OR = 3.3), and irritability (OR = 2.7). Children aged <2 years, had history of prematurity (OR = 2.0) and recent respiratory infections (OR = 1.3) were more likely to get infected by RSV. Children with SARI had higher positive rate of RSV than those with ILI. Cough, rhinorrhea, and wheezing were the most common symptoms in RSV infection. Children aged <2 years, had history of prematurity and recent respiratory infections were the potential risk factors for RSV infection.

Clinical characteristics and outcome of respiratory syncytial virus infection among adults hospitalized with influenza-like illness in France

OBJECTIVES

The aim of this study was to analyse characteristics and outcome of respiratory syncytial virus (RSV) infection in adults hospitalized with influenza-like illness (ILI).

METHODS

Patients hospitalized with ILI were included in this prospective, multicentre study carried out in six French hospitals during three consecutive influenza seasons (2012-2015). RSV and other respiratory viruses were detected by multiplex PCR in nasopharyngeal swabs. Risk factors for RSV infection were identified by backward stepwise logistic regression analysis.

RESULTS

A total of 1452 patients hospitalized with ILI were included, of whom 59% (861/1452) were >65 years and 83% (1211/1452) had underlying chronic illnesses. RSV was detected in 4% (59/1452), and influenza virus in 39% (566/1452). Risk factors for RSV infection were cancer (adjusted OR 2.1, 95% CI 1.1-4.1, p 0.04), and immunosuppressive treatment (adjusted OR 2.0, 95% CI 1.1-3.8, p 0.03). Patients with RSV had a median length of stay of 9 days (6-25), and 57% of them (30/53) had complications, including pneumonia (23/53, 44%) and respiratory failure (15/53, 28%). Fifteen per cent (8/53) were admitted to an intensive care unit, and the in-hospital mortality rate was 8% (4/53). Pneumonia was more likely to occur in patients with RSV than in patients with RSV-negative ILI (44% (23/53) versus 26% (362/1393), p 0.006) or with influenza virus infection (44% versus 28% (157/560), p 0.02).

CONCLUSION

RSV is an infrequent cause of ILI during periods of influenza virus circulation but can cause severe complications in hospitalized adults. Risk factors for RSV detection in adults hospitalized with ILI include cancer and immunosuppressive treatment. Specific immunization and antiviral therapy might benefit patients at risk.

Epidemiology and Molecular Characterization of Human Respiratory Syncytial Virus in Senegal after Four Consecutive Years of Surveillance, 2012-2015

Background

The burden of respiratory syncytial virus (RSV) infection remains poorly defined in Africa. To address this, we carried out a descriptive and retrospective pilot study, with a focus on the epidemiology of RSV in Senegal after 4 years of surveillance.

Methodology and Results

From January 2012 to October 2015 swabs were collected from consenting ILI outpatients. Viral detection was performed using RV16 kit enabling direct subtyping of RSV-A and B. For the molecular characterization of HRSV, the second hypervariable region of the Glycoprotein (G) gene was targeted for sequencing. We enrolled 5338 patients with 2803 children younger than five years of age (52.5%). 610 (11.4%) were positive for RSV infection: 276 (45.2%) were group A infections, 334 (54.8%) were group B infections and 21 (3.4%) were A/B co-infections. RSV detection rate is significantly higher (P < 0.0001) in children below 5 years. We noted that the annual distribution of RSV varied substantially by season and for the predominant subtype. Globally, results show a clear circulation pattern in the second half of each year; between June and September and possibly extended into November. The majority of RSV-A strains from Senegal clustered with strains that were previously assigned NA1 and novel ON1 genotype sequences. RSV-B sequences from Senegal clustered with the BA9 genotype. At the amino acid level, RSV-A strains from Senegal show proximity with the genotype ON1 characterized by a 72 nt insertion in G, resulting in 24 extra amino acids of which 23 are duplications of aa 261–283.

Conclusion

Globally our results show a clear circulation pattern of RSV in the second half of each year, between June and September and possibly extending into November, with children under 5 being more susceptible. Molecular studies identified the novel strains ON1 and BA9 as the major genotypes circulating in Senegal between 2012 and 2015.

Evaluation of case definitions to detect respiratory syncytial virus infection in hospitalized children below 5 years in Rural Western Kenya, 2009-2013

Background

In order to better understand respiratory syncytial virus (RSV) epidemiology and burden in tropical Africa, optimal case definitions for detection of RSV cases need to be identified.

Methods

We used data collected between September 2009 - August 2013 from children aged <5 years hospitalized with acute respiratory Illness at Siaya County Referral Hospital. We evaluated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of individual signs, symptoms and standard respiratory disease case definitions (severe acute respiratory illness [SARI]; hospitalized influenza-like illness [hILI]; integrated management of childhood illness [IMCI] pneumonia) to detect laboratory-confirmed RSV infection. We also evaluated an alternative case definition of cough or difficulty breathing plus hypoxia, in-drawing, or wheeze.

Results

Among 4714 children hospitalized with ARI, 3810 (81 %) were tested for RSV; and 470 (12 %) were positive. Among individual signs and symptoms, cough alone had the highest sensitivity to detect laboratory-confirmed RSV [96 %, 95 % CI (95–98)]. Hypoxia, wheezing, stridor, nasal flaring and chest wall in-drawing had sensitivities ranging from 8 to 31 %, but had specificities >75 %. Of the standard respiratory case definitions, SARI had the highest sensitivity [83 %, 95 % CI (79–86)] whereas IMCI severe pneumonia had the highest specificity [91 %, 95 % CI (90–92)]. The alternative case definition (cough or difficulty breathing plus hypoxia, in-drawing, or wheeze) had a sensitivity of [55 %, 95 % CI (50–59)] and a specificity of [60 %, 95 % CI (59–62)]. The PPV for all case definitions and individual signs/symptoms ranged from 11 to 20 % while the negative predictive values were >87 %. When we stratified by age <1 year and 1- < 5 years, difficulty breathing, severe pneumonia and the alternative case definition were more sensitive in children aged <1 year [70 % vs. 54 %, p < 0.01], [19 % vs. 11 %, p = 0.01] and [66 % vs. 43 %, p < 0.01] respectively, while non-severe pneumonia was more sensitive [14 % vs. 26 %, p < 0.01] among children aged 1- < 5 years.

Conclusion

The sensitivity and specificity of different commonly used case definitions for detecting laboratory-confirmed RSV cases varied widely, while the positive predictive value was consistently low. Optimal choice of case definition will depend upon study context and research objectives.