Medically attended respiratory syncytial virus infections in adults aged ≥ 50 years: clinical characteristics and outcomes

What 'case definition' for respiratory syncytial virus infection? Results of a systematic literature review to improve surveillance among the adults

BACKGROUND

Human respiratory syncytial virus (hRSV) is a leading cause of acute lower respiratory tract infection in frail individuals, including children, the elderly and immunocompromised people, with mild to severe symptoms. World Health Organization claims hRSV causes most elderly influenza-like illnesses (ILI) and severe acute respiratory infections (SARI). In this study, different case definitions for hRSV surveillance were examined for accuracy.

METHODS

The following search query ('Respiratory Syncytial Virus' OR 'RSV' OR 'hRSV' AND 'case definition') was used on PubMed/MEDLINE and Scopus with a 15-year-old baseline age restriction to conduct a systematic literature review.

RESULTS

Of 12 records, 58% employed the SARI definition, 50% the ILI definition and 42% the acute respiratory infection (ARI) definition, with some overlap. In young adults (18-64 years old), most studies show RSV prevalence between 6.25 and 72.54 cases per 1000 per year, and 19.23 to 98.5 in older adults. The outpatient ARI and hospitalized SARI criteria are particularly sensitive and specific.

CONCLUSIONS

Disease burden measurement requires a clear case definition; however, current literature is questionable. Currently, hRSV surveillance uses numerous case definitions with debatable accuracy. The epidemiology, clinical characteristics, and disease burden of hRSV are difficult to characterize without a standard surveillance case definition.

From Forgotten Pathogen to Target for New Vaccines: What Clinicians Need to Know about Respiratory Syncytial Virus Infection in Older Adults

Respiratory syncytial virus (RSV) is increasingly recognized as being implicated in acute illness in older adults, with a significant weight in hospitalizations for respiratory illness and death. By means of a best-evidence review, this paper aims to investigate whether RSV can be considered a forgotten pathogen in older patients, looking at trends in the literature volume and exploring possible epidemiological and clinical features underlying the focus given to it. We then present an assessment of its disease burden and present and future strategies for its reduction, particularly in light of the recent availability of new vaccines.

Estimation of the Number of Respiratory Syncytial Virus-Associated Hospitalizations in Adults in the European Union

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in adults that can result in hospitalizations. Estimating RSV-associated hospitalization is critical for planning RSV-related healthcare across Europe.

METHODS

We gathered RSV-associated hospitalization estimates from the RSV Consortium in Europe (RESCEU) for adults in Denmark, England, Finland, Norway, Netherlands, and Scotland from 2006 to 2017. We extrapolated these estimates to 28 European Union (EU) countries using nearest-neighbor matching, multiple imputations, and 2 sets of 10 indicators.

RESULTS

On average, 158 229 (95% confidence interval [CI], 140 865-175 592) RSV-associated hospitalizations occur annually among adults in the EU (≥18 years); 92% of these hospitalizations occur in adults ≥65 years. Among 75-84 years, the annual average is estimated at 74 519 (95% CI, 69 923-79 115) at a rate of 2.24 (95% CI, 2.10-2.38) per 1000. Among ≥85 years, the annual average is estimated at 37 904 (95% CI, 32 444-43 363) at a rate of 2.99 (95% CI, 2.56-3.42).

CONCLUSIONS

Our estimates of RSV-associated hospitalizations in adults are the first analysis integrating available data to provide the disease burden across the EU. Importantly, for a condition considered in the past to be primarily a disease of young children, the average annual hospitalization estimate in adults was lower but of a similar magnitude to the estimate in young children (0-4 years): 158 229 (95% CI, 140 865-175 592) versus 245 244 (95% CI, 224 688-265 799).

Diabetes and bacterial co-infection are two independent risk factors for respiratory syncytial virus disease severity

Diabetes mellitus (DM) is common among older adults hospitalized with lower respiratory tract infection, yet information on the impact of DM on disease severity is limited. This study retrospectively analyzed 46 Turkish patients infected with respiratory syncytial virus (RSV), with information on their comorbidities, co-infection status, and symptoms. Patients are grouped into four severity levels from mild to severe, according to lung parenchymal infiltration status and oxygen level. Similar to previously published studies, we found that comorbidities of diabetes, heart failure, hypertension, co-infection of any type, bacterial co-infection, and age are associated with the disease severity. Cough is the most common symptom (89%) followed by fever (26%) and myalgia, dyspnea, and weakness (around 20%). Using a second-order analysis (two-variable regression), we identified two independent risks for disease severity, the first is represented by diabetes, and the second is represented by bacterial co-infection. We observed two patients whose more severe symptoms were not associated with an older age, but associated with a combination of diabetes and bacterial co-infection. To confirm the true causality from the statistical correlation, further studies are needed.

The road to approved vaccines for respiratory syncytial virus

After decades of work, several interventions to prevent severe respiratory syncytial virus (RSV) disease in high-risk infant and older adult populations have finally been approved. There were many setbacks along the road to victory. In this review, I will discuss the impact of RSV on human health and how structure-based vaccine design set the stage for numerous RSV countermeasures to advance through late phase clinical evaluation. While there are still many RSV countermeasures in preclinical and early-stage clinical trials, this review will focus on products yielding long-awaited efficacy results. Finally, I will discuss some challenges and next steps needed to declare a global victory against RSV.

Burden of illness associated with Respiratory Syncytial Virus (RSV)-related hospitalizations among adults in Ontario, Canada: A retrospective population-based study

BACKGROUND

Globally, RSV is a common viral pathogen that causes 64 million acute respiratory infections annually. Our objective was to determine the incidence of hospitalization, healthcare resource use and associated costs of adults hospitalized with RSV in Ontario, Canada.

METHODS

To describe the epidemiology of adults hospitalized with RSV, we used a validated algorithm applied to a population-based healthcare utilization administrative dataset in Ontario, Canada. We created a retrospective cohort of incident hospitalized adults with RSV between September 2010 and August 2017 and followed each person for up to two years. To determine the burden of illness associated with hospitalization and post-discharge healthcare encounters each RSV-admitted patient was matched to two unexposed controls based on demographics and risk factors. Patient demographics were described and mean attributable 6-month and 2-year healthcare costs (2019 Canadian dollars) were estimated.

RESULTS

There were 7,091 adults with RSV-associated hospitalizations between 2010 and 2019 with a mean age of 74.6 years; 60.4 % were female. RSV-coded hospitalization rates increased from 1.4 to 14.6 per 100,000 adults between 2010-2011 and 2018-2019. The mean difference in healthcare costs between RSV-admitted patients and matched controls was $28,260 (95 % CI: $27,728 - $28,793) in the first 6 months and $43,721 over 2 years (95 % CI: $40,383 - $47,059) post-hospitalization.

CONCLUSIONS

RSV hospitalizations among adults increased in Ontario between 2010/11 to 2018/19 RSV seasons. RSV hospitalizations in adults were associated with increased attributable short-term and long-term healthcare costs compared to matched controls. Interventions that could prevent RSV in adults may reduce healthcare burden.

Prevalence and Clinical Outcomes of Respiratory Syncytial Virus vs Influenza in Adults Hospitalized With Acute Respiratory Illness From a Prospective Multicenter Study

BACKGROUND

Current understanding of severe respiratory syncytial virus (RSV) infections in adults is limited by clinical underrecognition. We compared the prevalence, clinical characteristics, and outcomes of RSV infections vs influenza in adults hospitalized with acute respiratory illnesses (ARIs) in a prospective national surveillance network.

METHODS

Hospitalized adults who met a standardized ARI case definition were prospectively enrolled across 3 respiratory seasons from hospitals participating across all sites of the US Hospitalized Adult Influenza Vaccine Effectiveness Network (2016-2019). All participants were tested for RSV and influenza using real-time reverse-transcription polymerase chain reaction assay. Multivariable logistic regression was used to test associations between laboratory-confirmed infection and characteristics and clinical outcomes.

RESULTS

Among 10 311 hospitalized adults, 6% tested positive for RSV (n = 622), 18.8% for influenza (n = 1940), and 75.1% negative for RSV and influenza (n = 7749). Congestive heart failure (CHF) or chronic obstructive pulmonary disease (COPD) was more frequent with RSV than influenza (CHF: 37.3% vs 28.8%, P < .0001; COPD: 47.6% vs 35.8%, P < .0001). Patients with RSV more frequently had longer admissions (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.06-1.80) for stays >1 week) and mechanical ventilation (OR, 1.45; 95% CI, 1.09-1.93) compared with influenza but not compared with the influenza-negative group (OR, 1.03; 95% CI, .82-1.28 and OR, 1.17; 95% CI, .91-1.49, respectively).

CONCLUSIONS

The prevalence of RSV across 3 seasons was considerable. Our findings suggest that those with RSV have worse outcomes compared with influenza and frequently have cardiopulmonary conditions. This study informs future vaccination strategies and underscores a need for RSV surveillance among adults with severe ARI.

Incidence of Respiratory Syncytial Virus Infection in Older Adults: Limitations of Current Data

INTRODUCTION

Respiratory syncytial virus (RSV) is an important cause of severe respiratory illness in older adults and adults with respiratory or cardiovascular comorbidities. Published estimates of its incidence and prevalence in adult groups vary widely. This article reviews the potential limitations affecting RSV epidemiology studies and suggests points to consider when evaluating or designing them.

METHODS

Studies reporting the incidence or prevalence of RSV infection in adults in high-income Western countries from 2000 onwards were identified via a rapid literature review. Author-reported limitations were recorded, together with presence of other potential limitations. Data were synthesized narratively, with a focus on factors affecting incidence estimates for symptomatic infection in older adults.

RESULTS

A total of 71 studies met the inclusion criteria, most in populations with medically attended acute respiratory illness (ARI). Only a minority used case definitions and sampling periods tailored specifically to RSV; many used influenza-based or other criteria that are likely to result in RSV cases being missed. The great majority relied solely on polymerase chain reaction (PCR) testing of upper respiratory tract samples, which is likely to miss RSV cases compared with dual site sampling and/or addition of serology. Other common limitations were studying a single season, which has potential for bias due to seasonal variability; failure to stratify results by age, which underestimates the burden of severe disease in older adults; limited generalizability beyond a limited study setting; and absence of measures of uncertainty in the reporting of results.

CONCLUSIONS

A significant proportion of studies are likely to underestimate the incidence of RSV infection in older adults, although the effect size is unclear and there is also potential for overestimation. Well-designed studies, together with increased testing for RSV in patients with ARI in clinical practice, are required to accurately capture both the burden of RSV and the potential public health impact of vaccines.

Targeted Literature Review of the Burden of Respiratory Syncytial Infection among High-Risk and Elderly Patients in Asia Pacific Region

INTRODUCTION

The burden of respiratory syncytial virus (RSV), which causes acute respiratory illness, is well recognized among the pediatric population but also imposes a significant risk to the elderly (age ≥ 60) and those with underlying comorbidities. The study aimed to review the most recent data on epidemiology and burden (clinical and economic) of RSV in the elderly/high-risk populations in China, Japan, South Korea, Taiwan, and Australia.

METHODS

A targeted review was conducted of English, Japanese, Korean, and Chinese language articles published from 1 January 2010 to 7 October 2020 relevant for the purpose.

RESULTS

A total of 881 studies were identified, and 41 were included. The median proportion of elderly patients with RSV in all adult patients with acute respiratory infection (ARI) or community acquired pneumonia was 79.78% (71.43-88.12%) in Japan, 48.00% (3.64-80.00%) in China, 41.67% (33.33-50.00%) in Taiwan, 38.61% in Australia, and 28.57% (22.76-33.33%) in South Korea. RSV was associated with a high clinical burden on those patients with comorbidities such as asthma and chronic obstructive pulmonary disease. In China, inpatients with ARI showed a significantly higher rate of RSV-related hospitalization than outpatients (13.22% versus 4.08%, p < 0.01). The median length of hospital stay among elderly patients with RSV was longest in Japan (30 days) and shortest in China (7 days). Mortality data varied by region with some studies reporting rates as high as 12.00% (9/75) in hospitalized elderly patients. Finally, data on the economic burden was only available for South Korea, with the median cost of a medical admission for an elderly patient with RSV being US dollar (USD) 2933.

CONCLUSION

RSV infection is a major source of disease burden among elderly patients, especially in regions with aging populations. It also complicates the management of those with underlying diseases. Appropriate prevention strategies are required to reduce the burden among the adult, especially the elderly, population. Data gaps regarding economic burden of RSV infection in the Asia Pacific region indicates the need for further research to increase our understanding on the burden of this disease in this region.

Assessing the patient experience of respiratory syncytial virus infection: development of a patient-reported outcome measure

BACKGROUND

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in older adults. Despite a number of RSV vaccine candidates in clinical trials, there are no existing disease-specific, self-reported measures that assess the symptoms and severity of RSV infection from the perspective of adult patients with acute RSV. The objective of this study was to describe the initial conceptualization and development of the RSV Infection, Intensity and Impact Questionnaire (RSV-iiiQ), a new patient-reported outcome measure.

METHODS

A targeted review of the literature identified relevant existing measures, symptoms, and impacts of RSV. A draft version of the RSV-iiiQ was developed based on the Influenza Intensity and Impact Questionnaire (Flu-iiQ) with expert input. Qualitative interviews (N = 20) were conducted with participants to optimize the RSV-iiiQ conceptual model and confirm the content validity of the RSV-iiiQ. Interviews included concept elicitation and a cognitive debriefing assessment. A draft conceptual framework was developed, and the electronic clinical outcome assessment was piloted. All steps of instrument development followed Food and Drug Administration guidance for patient-reported outcomes.

RESULTS

In-depth concept elicitation interviews followed by cognitive debriefings demonstrated that the content of the items was comprehensive, covered the breadth of RSV symptoms and impacts, and was relevant to the experiences of individuals with RSV. Both the paper and electronic versions of the RSV-iiiQ were easily completed. Minor refinements were made to some items based on participant feedback, and the draft conceptual framework was refined.

CONCLUSIONS

The RSV-iiiQ was developed for use in clinical trials to measure the symptom intensity and impact of acute RSV infection from the perspective of adult patients. The tool was developed in accordance with current regulatory guidance and is useful to support patient-focused drug development.

Impact of Respiratory Syncytial Virus and Influenza Virus Infection in the Adult Population in Spain between 2012 and 2020

Respiratory syncytial virus (RSV) infection is increasingly recognized as a cause of significant morbidity and mortality in adults. We aimed to estimate the rates of age-specific hospitalization and in-hospital mortality caused by acute lower respiratory tract infections (ALRTIs) in Spain between 2012 and 2020 and to compare the relative impact of RSV and influenza virus infection in adults. We used the discharge reports from the Minimum Basic Data Set to retrospectively analyze hospital discharge data on the basis of the ICD-9-CM and ICD-10-CM diagnosis codes. A total of 1,518,244 patients were hospitalized for ALRTIs, of whom 137,794 (9.1%) were admitted for RSV-related infections and 46,288 (3.0%) for influenza-related infections. In patients aged 60 years or older, the hospitalization rates (per 100,000 population) were estimated at 1.69 (95% CI 1.68-1.70) and 2.72 (95% CI 2.71-2.73) for RSV and influenza patients, respectively. However, in-hospital mortality rates were significantly higher among RSV patients than among influenza patients, 7.91% (95% CI 7.89-7.93) (83.0% of all RSV-related deaths) versus 6.91% (95% CI 6.89-6.93) (85.6% of all influenza-related deaths), respectively (p = 0.007). RSV-associated in-hospital mortality increases exponentially with age, posing a greater risk for older adults, particularly frail and high-risk patients.

Vaccine Efficacy in Adults in a Respiratory Syncytial Virus Challenge Study

BACKGROUND

Although human respiratory syncytial virus (RSV) is an important cause of illness and death in older adults, no RSV vaccine has been licensed.

METHODS

In a phase 2a study, we randomly assigned healthy adults (18 to 50 years of age), in a 1:1 ratio, to receive a single intramuscular injection of either bivalent prefusion F (RSVpreF) vaccine or placebo. Approximately 28 days after injection, participants were inoculated intranasally with the RSV A Memphis 37b challenge virus and observed for 12 days. The per-protocol prespecified primary end points were the following: reverse-transcriptase-quantitative polymerase-chain-reaction (RT-qPCR)-confirmed detectable RSV infection on at least 2 consecutive days with at least one clinical symptom of any grade from two categories or at least one grade 2 symptom from any category, the total symptom score from day 1 to discharge, and the area under the curve (AUC) for the RSV viral load in nasal-wash samples measured by means of RT-qPCR from day 2 after challenge to discharge. In addition, we assessed immunogenicity and safety.

RESULTS

After participants were inoculated with the challenge virus, vaccine efficacy of 86.7% (95% CI, 53.8 to 96.5) was observed for symptomatic RSV infection confirmed by any detectable viral RNA on at least 2 consecutive days. The median AUC for the RSV viral load (hours × log₁₀ copies per milliliter) as measured by RT-qPCR assay was 0.0 (interquartile range, 0.0 to 19.0) in the vaccine group and 96.7 (interquartile range, 0.0 to 675.3) in the placebo group. The geometric mean factor increase from baseline in RSV A-neutralizing titers 28 days after injection was 20.5 (95% CI, 16.6 to 25.3) in the vaccine group and 1.1 (95% CI, 0.9 to 1.3) in the placebo group. More local injection-site pain was noted in the vaccine group than in the placebo group. No serious adverse events were observed in either group.

CONCLUSIONS

RSVpreF vaccine was effective against symptomatic RSV infection and viral shedding. No evident safety concerns were identified. These findings provide support for further evaluation of RSVpreF vaccine in a phase 3 efficacy study. (Funded by Pfizer; EudraCT number, 2020-003887-21; ClinicalTrials.gov number, NCT04785612.).

A Phase 1/2 Study of a Respiratory Syncytial Virus Prefusion F Vaccine With and Without Adjuvant in Healthy Older Adults

BACKGROUND

Respiratory syncytial virus (RSV) is an important cause of disease in older adults. We evaluated the safety and immunogenicity of a stabilized RSV prefusion F subunit (RSVpreF) vaccine candidate with/without adjuvant in adults aged 65-85 years.

METHODS

Primary cohort participants were equally randomized to 1 of 7 RSVpreF formulations: 60 µg with either Al(OH)3 or CpG/Al(OH)3, 120 µg with either Al(OH)3 or CpG/Al(OH)3, 240 µg with either Al(OH)3 or CpG/Al(OH)3, 240 µg unadjuvanted, or placebo, administered concomitantly with high-dose seasonal inactivated influenza vaccine (SIIV). Participants in the month 0,2 cohort were randomized to RSVpreF 240 µg with CpG/Al(OH)3 or placebo, administered at months 0 and 2.

RESULTS

All RSVpreF vaccine candidates elicited robust and persistent serum neutralizing responses when administered alone or with SIIV. There was no notable difference in neutralizing response between the formulations, including those containing CpG. In the month 0,2 cohort, there was no booster effect of dose 2. SIIV responses were similar or slightly lower with concomitant administration of RSVpreF. Most systemic and local reactions were mild and more frequent after RSVpreF than placebo.

CONCLUSIONS

RSVpreF formulations were well tolerated and elicited robust neutralizing responses in older adults; however, CpG/Al(OH)3 did not further enhance responses. Clinical Trials Registration. NCT03572062.

Phase 1/2 Randomized Study of the Immunogenicity, Safety and Tolerability of an RSV Prefusion F Vaccine in Adults With Concomitant Inactivated Influenza Vaccine

Background

Respiratory syncytial virus (RSV) causes substantial morbidity and mortality in older adults and adults with comorbidities. An effective vaccine is needed. An investigational bivalent prefusion F vaccine (RSVpreF) was assessed in healthy adults.

Methods

This phase 1/2 study randomized adults 18–85 years old to receive placebo or 60, 120, or 240 µg RSVpreF (with or without aluminum hydroxide) alone or concomitantly with seasonal inactivated influenza vaccine (SIIV). Safety and immunogenicity were assessed.

Results

In older adults, reactogenicity events were predominantly mild or moderate among RSVpreF recipients; adverse events through 1 month postvaccination were similar across formulations. Coadministration with SIIV did not appear to affect safety among younger or older adults. All RSVpreF formulations with or without concomitant SIIV elicited robust RSV serum-neutralizing responses in adults aged 50–85 years 1 month postvaccination. Neutralizing titers 1 and 12 months postvaccination were 6.9–14.9 and 2.9–4.5 times, respectively, those before vaccination. SIIV immune responses trended lower when coadministered with RSVpreF.

Conclusions

RSVpreF formulations administered alone or with SIIV were well tolerated and highly immunogenic in older adults, supporting the potential for RSVpreF to protect older adults from RSV disease.

Clinical Trials Registration

NCT03529773.

Respiratory Syncytial Virus

Human respiratory syncytial virus (RSV) is a negative sense single-stranded RNA virus that can result in epidemics of seasonal respiratory infections. Generally, one of the two genotypes (A and B) predominates in a single season and alternate annually with regional variation. RSV is a known cause of disease and death at both extremes of ages in the pediatric and elderly, as well as immunocompromised populations. The clinical impact of RSV on the hospitalized adults has been recently clarified with the expanded use of multiplex molecular assays. Among adults, RSV can produce a wide range of clinical symptoms due to upper respiratory tract infections potentially leading to severe lower respiratory tract infections, as well as exacerbations of underlying cardiac and lung diseases. While supportive care is the mainstay of therapy, there are currently multiple therapeutic and preventative options under development.

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.

Etiology of viral respiratory tract infections in hospitalized adults, and evidence of the high frequency of prehospitalization antibiotic treatment in Norway

BACKGROUND AND AIMS

Respiratory tract infections (RTIs) cause considerable morbidity and mortality in all age groups, but the epidemiology and role of several of the viral RTIs in the adult and elderly patients are still unclear, as is the extent of prehospitalization antibacterial drug use in this population.

METHODS

We conducted a three-year (2015-2018) observational study of viral RTIs in hospitalized patients in a 500-bed hospital in Southeastern Norway, including all patients ≥18 years with RTI symptoms where one of the following viral agents was detected in a respiratory specimen (Seegene Allplex): Influenza A/B, RSV A/B, human metapneumovirus (hMPV), adenovirus and parainfluenza virus 1-4. Viral findings, demographical data, and information on prehospital antibiotic prescriptions were recorded.

RESULTS

In 1182 patients 1222 viral infection events occurred. The mean patient age was 69.6 years, and 53% were females. Influenza virus A/B (63%), RSV A/B (15%) and hMPV (13%) were the most common agents detected. The proportional burden of influenza A H1 was found to be relatively high (65%) in the age groups <69 years, compared to older patients (P = .001, chi-square).As many as 20% of the patients had been treated with antibiotics prior to admission, with the lowest rate for influenza A H3 group at 17% (P = .036, chi-square), and highest for the RSV group at 28% (P = .004, chi-square).Oseltamivir was prescribed prior to hospitalization in only 3 cases (0.2%).

CONCLUSIONS

We found a high rate of prehospital antibiotic prescription in adults hospitalized with viral RTIs, warranting better stewardship programs to tackle the increasing antibiotic resistance problem.

Disease Burden Estimates of Respiratory Syncytial Virus related Acute Respiratory Infections in Adults With Comorbidity: A Systematic Review and Meta-Analysis

BACKGROUND

Respiratory syncytial virus related acute respiratory infection (RSV-ARI) constitutes a substantial disease burden in adults with comorbidities. We aimed to identify all studies investigating the disease burden of RSV-ARI in this group.

METHODS

We estimated the incidence, hospitalization rate, and in-hospital case fatality ratio (hCFR) of RSV-ARI in adults with comorbidities based on a systematic review of studies published between January 1996 and March 2020. We also investigated the association between RSV-ARI and any comorbidity in adults. Meta-analyses based on random effects model were carried out.

RESULTS

Overall, 20 studies were included. The annual incidence rate of RSV-ARI in adults with any comorbidity was 37.6 (95% confidence interval [CI], 20.1-70.3) per 1000 persons per year in industrialized countries and the seasonal incidence rate was 28.4 (11.4-70.9) per 1000 persons per season. The hCFR in industrialized countries was 11.7% (5.8%-23.4%). There were no studies in developing countries. There were insufficient data to generate the meta-estimate of hospitalization rate. The likelihood of experiencing RSV-ARI for those with any comorbidity compared to those without was estimated to be 4.1 (odds ratio [OR], 1.6-10.4) and 1.1 (OR, 0.6-1.8) from studies using univariable and multivariable analysis respectively.

CONCLUSION

The disease burden of RSV-ARI among adults with comorbidity is substantial with limited data available.

In-hospital and midterm out-hospital complications of adults hospitalised with respiratory syncytial virus infection in France, 2017-2019: an observational study

OBJECTIVES

To describe the clinical characteristics and in/out-hospital outcomes of respiratory syncytial virus (RSV) infection among adults hospitalised with influenza-like illness (ILI) and compared against patients admitted for influenza.

METHODS

Adults hospitalised with ILI were prospectively included from five French university hospitals over two consecutive winter seasons (2017/2018 and 2018/2019). RSV and influenza virus were detected by multiplex RT-PCR on nasopharyngeal swabs. RSV-positive patients were compared to RSV-negative and influenza-positive hospitalised patients. Poisson regression models were used to estimate the adjusted prevalence ratio (aPR) associated with in-hospital and post-discharge outcomes between RSV and influenza infections. The in-hospital outcome was a composite of the occurrence of at least one complication, length of stay ≥7 days, intensive care unit (ICU) admission, use of mechanical ventilation and in-hospital death. Post-discharge outcome included 30/90-day all-cause mortality and 90-day readmission rates.

RESULTS

Overall, 1,428 hospitalised adults with ILI were included. RSV was detected in 8% (114/1428) and influenza virus in 31% (437/1428). Patients hospitalised with RSV were older than those with influenza (mean age, 73.0 versus 68.8 years; p=0.015) with a higher frequency of respiratory (52% versus 39%, p=0.012) or cardiac chronic diseases (52% versus 41%, p=0.039) and longer hospitalisation duration (median stay 8 versus 6 days, p<0.001). Anti-influenza therapies were less prescribed among RSV than influenza patients (20% versus 66%, p<0.001). In-hospital composite outcome was poorer in RSV patients (adjusted prevalence ratio (aPR)=1.5; 95% Confidence Interval (95% CI) 1.1-2.1) than in those hospitalised with influenza. No difference was observed for the post-discharge composite outcome (aPR=1.1; 95% CI 0.8-1.6).

CONCLUSION

RSV infection results in serious respiratory illness with in-hospital outcomes worse than influenza and with similar midterm post-discharge outcomes.

Incidence of respiratory syncytial virus related health care utilization in the United States

Background

Respiratory Syncytial Virus (RSV) is one of the most frequent causes of acute respiratory infection worldwide. Understanding age-specific health care utilization is necessary to guide effective prevention strategies. This retrospective database analysis assessed the incidence rates of RSV-related health care utilization in the USA over a 7-year period.

Methods

Episodes of RSV were identified in the Truven Health MarketScan^® Commercial Claims and Encounters database between 2008 and 2014 using ICD-9-CM codes for pneumonia, bronchiolitis and RSV (480-486, 487.0, 466.1, 491.2, 079.6). Annual RSV-related health care utilization was calculated for the total population, by age group (<1, 1, 2-4, 5-17, 18-49, 50-64, 65-74, 75-84 and ≥85 years) and the proportion of cases for each setting (hospitalization, outpatient, or emergency department [ED] / urgent care [UC]).

Results

Over the 7-year study period, the mean rate of all RSV-associated health care utilization was 2.4 per 1000 person-years, with mean rates ranging from 2.0 to 2.6). The highest rate was seen in infants aged <1 year (mean 79.0 per 1000 over the 7-year period), which decreased with increasing age in the range 2-49 years before increasing with age in older adults (mean rate 8.1 per 1000 over the 7-year period in those ≥85 years). Of all RSV cases, 82% were reported in an outpatient setting, 11% in the ED/UC and 7% were hospitalized.

Conclusions

The annual RSV-related healthcare utilization rates were substantial, especially in infants and young children. These results underscore the need to accelerate the development of RSV prevention strategies to reduce the healthcare burden of RSV.

Hospital utilization rates for influenza and RSV: a novel approach and critical assessment

BACKGROUND

Influenza and respiratory syncytial virus (RSV) contribute significantly to the burden of acute lower respiratory infection (ALRI) inpatient care, but heterogeneous coding practices and availability of inpatient data make it difficult to estimate global hospital utilization for either disease based on coded diagnoses alone.

METHODS

This study estimates rates of influenza and RSV hospitalization by calculating the proportion of ALRI due to influenza and RSV and applying this proportion to inpatient admissions with ALRI coded as primary diagnosis. Proportions of ALRI attributed to influenza and RSV were extracted from a meta-analysis of 360 total sources describing inpatient hospital admissions which were input to a Bayesian mixed effects model over age with random effects over location. Results of this model were applied to inpatient admission datasets for 44 countries to produce rates of hospital utilization for influenza and RSV respectively, and rates were compared to raw coded admissions for each disease.

RESULTS

For most age groups, these methods estimated a higher national admission rate than the rate of directly coded influenza or RSV admissions in the same inpatient sources. In many inpatient sources, International Classification of Disease (ICD) coding detail was insufficient to estimate RSV burden directly. The influenza inpatient burden estimates in older adults appear to be substantially underestimated using this method on primary diagnoses alone. Application of the mixed effects model reduced heterogeneity between countries in influenza and RSV which was biased by coding practices and between-country variation.

CONCLUSIONS

This new method presents the opportunity of estimating hospital utilization rates for influenza and RSV using a wide range of clinical databases. Estimates generally seem promising for influenza and RSV associated hospitalization, but influenza estimates from primary diagnosis seem highly underestimated among older adults. Considerable heterogeneity remains between countries in ALRI coding (i.e., primary vs non-primary cause), and in the age profile of proportion positive for influenza and RSV across studies. While this analysis is interesting because of its wide data utilization and applicability in locations without laboratory-confirmed admission data, understanding the sources of variability and data quality will be essential in future applications of these methods.

Severity of RSV infection in Southern European elderly patients during two consecutive winter seasons (2017-2018)

In Europe, the respiratory syncytial virus (RSV) surveillance system is very heterogeneous and there is growing evidence of the importance of RSV infections resulting in hospitalization of elderly patients. The aim of this study was to assess the severity of RSV infection in the elderly living in the aged Southern European countries. We conducted a retrospective study of elderly patients ( ≥65‐year old) admitted for laboratory‐confirmed RSV infection in three tertiary hospitals in Portugal, Italy, and Cyprus over two consecutive winter seasons (2017–2018). Uni‐multivariable analyses were carried out to evaluate the effect of clinical variables on radiologically confirmed pneumonia, use of noninvasive ventilation (NIV), and in‐hospital death (IHD). A total of 166 elderly patients were included. Pneumonia was evident in 29.5%. NIV was implemented in 16.3%, length of stay was 11.8 ± 12.2 days, and IHD occurred in 12.1%. Multivariable analyses revealed that the risk of pneumonia was higher in patients with chronic kidney disease (CKD) (odds ratio [OR]: 2.57; 95% confidence interval [CI]: 1.12–5.91); the use of NIV was higher in patients with obstructive sleep apnea or obesity hypoventilation syndrome (OSA or OHS) (OR: 5.38; 95% CI: 1.67–17.35) and CKD (OR: 2.52; 95% CI: 1.01–6.23); the risk of IHD was higher in males (OR: 3.30; 95% CI: 1.07–10.10) and in patients with solid neoplasm (OR: 9.06; 95% CI: 2.44–33.54) and OSA or OHS (OR: 8.39; 95% CI: 2.14–32.89). Knowledge of factors associated with RSV infection severity may aid clinicians to set priorities and reduce disease burden. Development of effective antiviral treatment and vaccine against RSV is highly desirable.

Comparison of clinical characteristics and outcomes between respiratory syncytial virus and influenza-related pneumonia in China from 2013 to 2019

This study aims to compare clinical characteristics and severity between adults with respiratory syncytial virus (RSV-p) and influenza-related pneumonia (Flu-p). A total of 127 patients with RSV-p, 693 patients with influenza A-related pneumonia (FluA-p), and 386 patients with influenza B-related pneumonia (FluB-p) were retrospectively reviewed from 2013 through 2019 in five teaching hospitals in China. A multivariate logistic regression model indicated that age ≥ 50 years, cerebrovascular disease, chronic kidney disease, solid malignant tumor, nasal congestion, myalgia, sputum production, respiratory rates ≥ 30 beats/min, lymphocytes < 0.8×10⁹/L, and blood albumin < 35 g/L were predictors that differentiated RSV-p from Flu-p. After adjusting for confounders, a multivariate logistic regression analysis confirmed that, relative to RSV-p, FluA-p (OR 2.313, 95% CI 1.377–3.885, p = 0.002) incurred an increased risk for severe outcomes, including invasive ventilation, ICU admission, and 30-day mortality; FluB-p (OR 1.630, 95% CI 0.958–2.741, p = 0.071) was not associated with increased risk. Some clinical variables were useful for discriminating RSV-p from Flu-p. The severity of RSV-p was less than that of FluA-p, but was comparable to FluB-p.

Severe Morbidity and Short- and Mid- to Long-term Mortality in Older Adults Hospitalized with Respiratory Syncytial Virus Infection

BACKGROUND

We describe the clinical epidemiology and outcomes among a large cohort of older adults hospitalized with respiratory syncytial virus (RSV) infection in the United States.

METHODS

Hospitalized adults aged ≥60 years who tested positive for RSV between 1 January 2011 and 30 June 2015 were identified from Kaiser Permanente Southern California. Patient-level demographics, comorbidities, clinical presentation, utilization, complications, and mortality were evaluated.

RESULTS

There were 664 patients hospitalized with RSV (61% female, 64% aged ≥75 years). Baseline chronic diseases were prevalent (all >30%); 66% developed pneumonia, 80% of which were radiographically confirmed. Very severe tachypnea (≥26 breaths/minute) was common (56%); 21% required ventilator support and 18% were admitted to intensive care unit. Mortality during hospitalization was 5.6% overall (4.6% in 60-74 year olds and 6.1% in ≥75 year olds). Cumulative mortality within 1, 3, 6, and 12 months of admission was 8.6%, 12.3%, 17.2%, and 25.8%, respectively.

CONCLUSION

RSV infection in hospitalized older adults often manifested as severe, life-threatening lower respiratory tract illness with high rates of pneumonia, requirement for ventilatory support, and short- and long-term mortality. Increased recognition of the substantial RSV disease burden in adults will be important in evaluation and use of urgently needed interventions.

Severe Illnesses Associated With Outbreaks of Respiratory Syncytial Virus and Influenza in Adults

Background

Recent reports have described the contribution of adult respiratory syncytial virus (RSV) infections to the use of advanced healthcare resources and death.

Methods

Data regarding patients aged ≥18 years admitted to any of Maryland’s 50 acute-care hospitals were evaluated over 12 consecutive years (2001–2013). We examined RSV and influenza (flu) surveillance data from the US National Respiratory and Enteric Virus Surveillance System and the Centers for Disease Control and Prevention and used this information to define RSV and flu outbreak periods in the Maryland area. Outbreak periods consisted of consecutive individual weeks during which at least 10% of RSV and/or flu diagnostic tests were positive. We examined relationships of RSV and flu outbreaks to occurrence of 4 advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) due to medically attended acute respiratory illness (MAARI).

Results

Occurrences of all 4 MAARI-related hospital advanced medical outcomes were consistently greater for all adult ages during RSV, flu, and combined RSV–flu outbreak periods compared to nonoutbreak periods and tended to be greatest in adults aged ≥65 years during combined RSV–flu outbreak periods. Rate ratios for all 4 MAARI-related advanced medical outcomes ranged from 1.04 to 1.38 during the RSV, flu, or combined RSV–flu outbreaks compared to the nonoutbreak periods, with all 95% lower confidence limits >1.

Conclusions

Both RSV and flu outbreaks were associated with surges in MAARI-related advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) for adults of all ages.

Epidemiology of Respiratory Syncytial Virus Across Five Influenza Seasons Among Adults and Children One Year of Age and Older-Washington State, 2011/2012-2015/2016

BACKGROUND

Vaccines and novel prophylactics against respiratory syncytial virus (RSV) are in development. To provide a baseline for evaluating these interventions, we characterized the incidence and molecular epidemiology of RSV in persons aged ≥1 year.

METHODS

We identified patients with medically attended acute respiratory illness (MAARI) from the 2011/2012 through 2015/2016 influenza seasons among members of Kaiser Permanente Washington. We estimated the cumulative incidence of MAARI for laboratory-confirmed RSV or influenza infection.

RESULTS

Annual cohorts ranged from 82 266 to 162 633 individuals, 14% of whom were children aged 1 to 17 years. Cumulative incidence of RSV each season ranged from 14 per 1000 population (95% confidence interval [CI], 12-16) to 22 per 1000 (95% CI, 19-25). Incidence of RSV was greater than influenza in children aged 12-23 months and 2-4 years; incidence of influenza was greater in other age groups. Respiratory syncytial virus subtype A dominated in 2011/2012, 2012/2013, and 2015/2016, with ON1 being the most common genotype. Respiratory syncytial virus subtype B dominated in 2013/2014 and 2014/2015, primarily of the BA genotype.

CONCLUSIONS

The burden of RSV is comparable to that of influenza across the life course. These results provide a baseline for evaluating the impact of new RSV interventions on the epidemiology of RSV.

Comparative virulence of seasonal viruses responsible for lower respiratory tract infections: a southern European multi-centre cohort study of hospital admissions

Objectives

Our study aimed to compare the clinical severity of lower respiratory tract infections (LRTI’s) caused by Influenza and Respiratory Syncytial Virus (RSV).

Methods

We conducted a retrospective cohort study of LRTI admissions with positive PCR results for Influenza or RSV from 2017 to 2019 in three teaching hospitals in southern Europe. Data on clinical characteristics, viral agents and disease outcome were collected. Nosocomial infection was excluded. Main outcomes were invasive mechanical ventilation and in-hospital death.

Results

A total of 984 patients were included. Median age was 75 years. Influenza A was the most frequently identified virus (56.5%), of which 27.1% were subtype H1N1 and 53.0% H3N2. Influenza B was isolated in 22.3% and RSV in 21.0%. There were 10.5% of patients who died during admission and 8.3% submitted to IMV. Influenza A H1N1 was associated with lower age and less co-morbidity, while the opposite was observed for RSV. Influenza A H1N1 was independently associated with both higher risk of death (adjusted odds ratio 2.0 [1.2–3.4] p = 0.008) and IMV (adjusted odds ratio 5.1 [3.0–8.5] p < 0.001).

Conclusion

Influenza A H1N1 was an independent predictor of mortality and IMV. These findings may have implications on hospital resource planning and vaccination policies.

Morbidity and mortality of respiratory syncytial virus infection in hospitalized adults: Comparison with seasonal influenza

INTRODUCTION

Respiratory syncytial virus (RSV) is considered a major pathogen that causes acute influenza-like illness. The objective of this study was to compare the clinical outcomes of patients with laboratory-confirmed RSV and patients with influenza infection.

METHODS

Adults hospitalized in Beilinson Hospital (October 2017-April 2018) with laboratory-confirmed RSV or influenza were included. The primary outcome was the composite of RSV/influenza complications: 30-day mortality, pneumonia, mechanical ventilation, vasopressor support, intensive care unit admission, and myocarditis/encephalitis. Secondary outcomes were individual components of the primary outcome, 90-day mortality, 90-day readmission, and length of hospital stay.

RESULTS

A total of 639 patients with RSV (n = 113) and influenza (n = 526) were included. The composite primary outcome was 21.4% (136/633), and was higher in RSV patients (30% (34/113) vs 19% (102/526), p = 0.002). Pneumonia was more common in RSV patients (21.2% (24/113) vs 9.1% (48/526), p = 0.001). On multivariable analysis, hypoalbuminemia (odds ratio (OR) 3.3, 95% confidence interval (CI) 2.1-5.3, p < 0.001), reduced room-air saturation (OR 1.1, 95% CI 1.02-1.1, p = 0.001), and infection with RSV (OR 1.67, 95% CI 1.01-2.76, p = 0.046) were predictors of complications.

CONCLUSIONS

RSV infection in hospitalized adults resulted in serious respiratory illness with complications that are comparable to those caused by influenza.

STAT1 participates in the induction of substance P expression in airway epithelial cells by respiratory syncytial virus

PURPOSE

The regulation effect and mechanism of respiratory syncytial virus (RSV) infection on the expression of tachykinin substance P (SP) in airway epithelial cells was investigated.

METHODS

The regulation of SP expression by RSV was investigated in the BEAS-2B airway epithelial cell line. RT-qPCR, immunofluorescence, and ELISA assay were used to examine the expression of the SP encoding gene TAC1, the intracellular SP protein expression, and the extracellular SP secretion.

RESULTS

The mRNA expression of TAC1 and the intracellular SP protein level in BEAS-2B cells were significantly enhanced by RSV infection with multiplicity of infection (MOI) values of both 1 and 0.1 at 48 hours post infection. Heat-inactivated and UV-inactivated RSV, but not live RSV, significantly induced SP secretion in both control BEAS-2B cells and CX3CR1 receptor knockout cells without affecting the TAC1 gene expression or cell viability. RSV G protein (2-10 μg/ml) and fractalkine (10-50 ng/ml), both CX3CR1 receptor ligands, did not affect SP secretion in BEAS-2B cells. Inhibition of STAT1 phosphorylation by fludarabine (1 μM) markedly reduced the RSV-induced TAC1 gene expression and antagonized the inhibition of RSV replication by interferon-α in BEAS-2B cells.

CONCLUSIONS

STAT1 participates in RSV infection-induced SP expression in airway epithelial cells.

Clinical characteristics and outcomes in adult patients hospitalized with influenza, respiratory syncytial virus and human metapneumovirus infections

Objectives: To compare the clinical characteristics and outcomes of patients hospitalized with respiratory syncytial virus (RSV), human metapneumovirus (hMPV), and influenza infections.Methods: This study prospectively enrolled 594 patients hospitalized with influenza-like illness (ILI) and laboratory-confirmed RSV, hMPV, or influenza infections over three consecutive influenza seasons at a tertiary hospital in China.Results: While certain clinical features were of value as predictors of infection type, none exhibited good predictive performance as a means of discriminating between these three infections (area under the receiver-operating characteristic curve < 0.70). After controlling for potential confounding variables, RSV infections in pneumonia patients were found to be associated with a 30-day mortality risk comparable to that of influenza patients [odds ratio (OR) 1.016, 95% confidence interval (CI) 0.267-3.856, p = 0.982], whereas hMPV infection was associated with a reduced risk of mortality (OR 0.144, 95% CI 0.027-0.780, p = 0.025). Among those without pneumonia, the 30-day mortality risk in patients with influenza was comparable to that in patients infected with RSV (OR 1.268, 95% CI 0.172-9.355, p = 0.816) or hMPV (OR 1.128, 95% CI 0.122-10.419, p = 0.916).Conclusion: Disease severity associated with these three types of viral infection was inconsistent when comparing patients with and without pneumonia, highlighting the importance of etiologic testing.

Clinical characteristics and disease burden of respiratory syncytial virus infection among hospitalized adults

The disease burden of respiratory syncytial virus (RSV) infection in the adult population has not been well characterized compared to children. Investigation of the clinical characteristics and disease burden of adult RSV infection would help to establish public health policy and a future vaccine strategy. We retrospectively collected medical records of hospitalized adult patients who were diagnosed with RSV infection from January 2012 to December 2015 from three tertiary hospitals. Baseline characteristics, clinical outcomes and economic charge during hospitalization were compared by age groups (19–49 years, 50–64 years, and ≥ 65 years) using Chi-square test. The odds of risk factors of RSV pneumonia were calculated using binary logistic regression. A total of 204 patients from three hospitals were enrolled. Patients who older than 65 years were 132 (64.7%). 118 (57.8%) patients had clinically confirmed pneumonia and 22 (10.8%) died in a hospital. The median medical cost of RSV pneumonia was 2,855.26 USD (interquartile range, 1,561.85–5,379.55) per each admission. Solid cancer (adjusted OR, 3.85; 95% CI, 1.65–9.02, p = 0.002) and hematologic malignancy (all patients had pneumonia) were shown to be risk factors for RSV pneumonia. RSV infection in South Korea seemed to have a significant burden among adults as pneumonia, care in the intensive care unit and mortality. Nationwide awareness and further effort to recognize the current burden, prepare specific treatment, and prevent adult RSV infection would be necessary.

The burden of respiratory syncytial virus in adults: a systematic review and meta-analysis

Respiratory syncytial virus (RSV) is the most common pathogen associated with acute lower respiratory tract infections in young children. RSV is also a major viral pathogen causing severe lung disease in the adult population, particularly among the elderly. We conducted a review of adult RSV studies published from January 1970 to February 2017 to determine the burden of disease among adults worldwide. There were no restrictions on health care setting or definition of RSV infection. A total of 1530 published studies were identified, 95 of which were included in this review. The incidence rates of hospitalised RSV acute respiratory tract infection (ARI) in adults >65 years old ranged from 7.3 to 13.0/10⁵ population in Africa and Asia and from 190 to 254/10⁵ population in the USA. Higher incidence rates (195–1790/10⁵ population) were observed in adults ≥50 years old for outpatient or emergency visits in the USA. Of all ARI patients, RSV accounted for 1–10% in adults and 2–14% in patients with chronic diseases or transplantation. Given the limitations in the existing data, significant efforts should be made to generate evidence on the burden of RSV infections in adults and to estimate the potential impact of future preventive interventions.

Evaluation of Efficacy Endpoints for a Phase IIb Study of a Respiratory Syncytial Virus Vaccine in Older Adults Using Patient-Reported Outcomes With Laboratory Confirmation

OBJECTIVES

There are no approved vaccines for respiratory syncytial virus (RSV), and consensus on methods to assess RSV vaccine efficacy has not been established. In this study of an adjuvanted RSV vaccine, we evaluated an RSV disease endpoint using a patient-reported outcome instrument (the inFLUenza Patient-Reported Outcome instrument [FLU-PRO]) and molecular testing for virologic confirmation.

METHODS

In a randomized, blinded efficacy study (NCT02508194), 1900 adult participants aged ≥60 years who had any respiratory symptom lasting ≥24 hours recorded symptoms in a FLU-PRO-based workbook for 21 days, self-collected nasal swabs on illness days 2 to 4, and had a site-collected swab obtained on (approximately) day 4. The endpoint, acute RSV-associated respiratory illness (ARA-RI), required specific symptoms with virologic confirmation.

RESULTS

The FLU-PRO demonstrated reliability, ability to detect change, and validity and had high participant adherence and acceptable patient burden in the setting of an RSV prevention trial. The ARA-RI endpoint definition captured all 33 virologically confirmed RSV illnesses for which symptom data were provided, and in 32 of these, at least 1 lower respiratory symptom was reported. Sensitivity analysis with an endpoint requiring ≥2 lower respiratory symptoms captured greater symptom severity but fewer cases. Results of self- and site-collected swabs were highly correlated. Self-swabbing detected 9 additional cases that would have been missed by site swabbing only.

CONCLUSIONS

These results demonstrated the reliability and validity of the ARA-RI definition and of the FLU-PRO for use in RSV studies. Self-swabbing improved RSV detection.

Post-pandemic influenza A/H1N1pdm09 is associated with more severe outcomes than A/H3N2 and other respiratory viruses in adult hospitalisations

This study compares the frequency and severity of influenza A/H1N1pdm09 (A/H1), influenza A/H3N2 (A/H3) and other respiratory virus infections in hospitalised patients. Data from 17 332 adult hospitalised patients admitted to Sir Charles Gairdner Hospital, Perth, Western Australia, with a respiratory illness between 2012 and 2015 were linked with data containing reverse transcription polymerase chain reaction results for respiratory viruses including A/H1, A/H3, influenza B, human metapneumovirus, respiratory syncytial virus and parainfluenza. Of these, 1753 (10.1%) had test results. Multivariable regression analyses were conducted to compare the viruses for clinical outcomes including ICU admission, ventilation, pneumonia, length of stay and death. Patients with A/H1 were more likely to experience severe outcomes such as ICU admission (OR 2.5, 95% CI 1.2–5.5, P = 0.016), pneumonia (OR 3.0, 95% CI 1.6–5.7, P < 0.001) and lower risk of discharge from hospital (indicating longer lengths of hospitalisation; HR 0.64 95% CI 0.47–0.88, P = 0.005), than patients with A/H3. Patients with a non-influenza respiratory virus were less likely to experience severe clinical outcomes than patients with A/H1, however, had similar likelihood when compared to patients with A/H3. Patients hospitalised with A/H1 had higher odds of severe outcomes than patients with A/H3 or other respiratory viruses. Knowledge of circulating influenza strains is important for healthcare preparedness.

T-Cell Responses in Adults During Natural Respiratory Syncytial Virus Infection

Background

The pathogenesis of respiratory syncytial virus (RSV) in older adults may be due to age-related T-cell immunosenescence. Thus, we evaluated CD4 and CD8 T-cell responses during RSV infection in adults across the age spectrum.

Methods

Peripheral blood mononuclear cells collected during RSV infection in adults, age 26-96 years, were stimulated with live RSV and peptide pools representing F, M, NP, and G proteins and analyzed by flow cytometry.

Results

There were no significant age-related differences in frequency of CD4+ T cells synthesizing interferon (IFN)γ, interleukin (IL)2, IL4, IL10, or tumor necrosis factor (TNF)α or in CD8+IFNγ+ T cells. IL4+CD4+ T-cell numbers were low, as were IL13 and IL17 responses. However, in univariate analysis, CD4 T-cell IFNγ, IL2, IL4, IL10, and TNFα responses and CD8+IFNγ+ T cells were significantly increased with more severe illness requiring hospitalization. In multivariate analysis, viral load was also associated with increased T-cell responses.

Conclusions

We found no evidence of diminished RSV-specific CD4 or CD8 T-cell responses in adults infected with RSV. However, adults with severe disease seemed to have more robust CD4 and CD8 T-cell responses during infection, suggesting that disease severity may have a greater association with T-cell responses than age.

Respiratory syncytial virus infection in adults

Human respiratory syncytial virus (RSV) belongs to the recently defined Pneumoviridae family, Orthopneumovirus genus. It is a negative sense, single stranded RNA virus that results in epidemics of respiratory infections that typically peak in the winter in temperate climates and during the rainy season in tropical climates. Generally, one of the two genotypes (A and B) predominates in a single season, alternating annually, although regional variation occurs. RSV is a cause of disease and death in children, older people, and immunocompromised patients, and its clinical effect on adults admitted to hospital is clarified with expanded use of multiplex molecular assays. Among adults, RSV produces a wide range of clinical symptoms including upper respiratory tract infections, severe lower respiratory tract infections, and exacerbations of underlying disease. Here we discuss the latest evidence on the burden of RSV related disease in adults, especially in those with immunocompromise or other comorbidities. We review current therapeutic and prevention options, as well as those in development.

Respiratory Syncytial Virus and Associations With Cardiovascular Disease in Adults

Respiratory syncytial virus (RSV) is historically known for causing respiratory illness in young children, but the appreciation of its impact on older adults is growing. Studies have shown that hospitalization for respiratory illness due to RSV is complicated by cardiovascular events in 14% to 22% of adult patients, including worsening congestive heart failure, acute coronary syndrome, and arrhythmias. Additionally, underlying cardiovascular disease is associated with hospitalization in 45% to 63% of adults with confirmed RSV. In summary, patients with cardiopulmonary disease have higher rates of health care utilization for RSV-related illness and worse outcomes. Patients with cardiovascular disease likely represent an important target population for the rapidly developing field of RSV vaccines.

Clinical manifestations and outcomes of respiratory syncytial virus infection in adult hospitalized patients

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Adult hospitalized patients with RSV were advanced age and had comorbidities.

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Cardiopulmonary complications were common.

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Major complication was pneumonia with acute respiratory failure.

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Pre-existing coronary arterial disease was a risk factor of cardiovascular complication.

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Pneumonia and acute myocardial infarction were the major causes of death.

Background

Respiratory syncytial virus (RSV) is an important virus found in adult hospitalized patients.

Objectives

To study the clinical outcomes of hospitalized patients aged ≥ 15 years and diagnosed with RSV infection.

Study design

Both retrospective and prospective cohort studies were conducted at a university hospital between May 2014 and December 2015. Results: RSV was detected in 86 of 1562(5.5%) adult hospitalized patients suspected of respiratory viral infection. Sixty-nine patients were included in the study. RSV was detected by RT-PCR (82.6%), IFA (10.1%), and both RT-PCR and IFA (7.3%). Most patients (87.0%) were aged ≥ 50 years. Cardiovascular diseases, pulmonary diseases, immunocompromised hosts, and diabetes were the major comorbidities. The common manifestations were cough (92.8%), dyspnea (91.3%), sputum production (87.0%), tachypnea (75.4%), wheezing (73.9%), and fever (71.0%). Fifty- five patients (79.7%) were diagnosed with pneumonia. Hypoxemia (SpO2 ≤ 92%) was found in 53.6% patients. Twenty-five of 69(36.2%) patients developed respiratory failure and required ventilatory support. Cardiovascular complications were found in 24.6% of patients. Congestive heart failure, acute myocardial infarction (MI), new atrial fibrillation, and supraventricular tachycardia were found in 9(13.0%), 7(10.1%), 4(5.8%), and 3(4.3%) of 69 patients, respectively. Overall mortality was 15.9%. Pneumonia (81.8%) and acute MI (18.2%) were the major causes of death.

Conclusions

Most adult hospitalized patients with RSV infection were of advanced age and had comorbidities. Cardiopulmonary complications were the major causes of death. Management and prevention of RSV infection in these vulnerable groups are necessary.

Environmental Cadmium Enhances Lung Injury by Respiratory Syncytial Virus Infection

Cadmium (Cd) is a naturally occurring environmental toxicant that disrupts mitochondrial function at occupational exposure levels. The impacts of Cd exposure at low levels through dietary intake remain largely uncharacterized. Human respiratory syncytial virus (RSV) causes severe morbidity, which can require hospitalization and result in death in young children and elderly populations. The impacts of environmental Cd exposure on the severity of RSV disease are unknown. Herein, we used a mouse model to examine whether Cd pre-exposure at a level of dietary intake potentiates pulmonary inflammation on subsequent infection with RSV. Mice were given Cd or saline in drinking water for 28 days. Subsets of these mice were infected with RSV at 5 days before the end of the study. Cd pre-exposure caused relatively subtle changes in lung; however, it elevated the IL-4 level and altered metabolites associated with fatty acid metabolism. After RSV infection, mice pre-exposed to Cd had elevated lung RSV titer and increased inflammation, as measured by histopathology, immune cell infiltration, cytokines, and chemokines. RSV infection after Cd pre-exposure also caused widespread perturbation in metabolism of glycerophospholipids and amino acids (Trp, Met, and Cys, branched-chain amino acids), as well as carnitine shuttle associated with mitochondrial energy metabolism. The results show that Cd burden by dietary intake potentiates RSV infection and severe disease with associated mitochondrial metabolic disruption.

Respiratory syncytial virus infection among adults during influenza season: A frequently overlooked diagnosis

Our objective is to assess the characteristics of respiratory syncytial virus (RSV) infection in adult patients and to establish differences with influenza viruses. Fifty-four patients diagnosed with RSV and 198 with influenza were prospectively included. Compared with influenza, empirical antimicrobial therapy was more frequent in patients diagnosed with RSV, whereas antibiotic withdrawal at the time of diagnosis confirmation was lower (OR, 0.12; CI, 95% 0.01-0.90; P = 0.040). RSV-positive patients were more likely to need hospital readmission (OR, 3.00; CI, 95% 0.98-9.09; P = 0.053). The role of RSV infection in adults is often overlooked, leading to inappropriate use of antibiotics and a probable increase in nosocomial RSV transmission.

Clinical Features, Severity, and Incidence of RSV Illness During 12 Consecutive Seasons in a Community Cohort of Adults ≥60 Years Old

Background

The epidemiology and burden of respiratory syncytial virus (RSV) illness are not well defined in older adults.

Methods

Adults ≥60 years old seeking outpatient care for acute respiratory illness were recruited from 2004–2005 through 2015–2016 during the winter seasons. RSV was identified from respiratory swabs by multiplex polymerase chain reaction. Clinical characteristics and outcomes were ascertained by interview and medical record abstraction. The incidence of medically attended RSV was estimated for each seasonal cohort.

Results

RSV was identified in 243 (11%) of 2257 enrollments (241 of 1832 individuals), including 121 RSV type A and 122 RSV type B. The RSV clinical outcome was serious in 47 (19%), moderate in 155 (64%), and mild in 41 (17%). Serious outcomes included hospital admission (n = 29), emergency department visit (n = 13), and pneumonia (n = 23) and were associated with lower respiratory tract symptoms during the enrollment visit. Moderate outcomes included receipt of a new antibiotic prescription (n = 144; 59%), bronchodilator/nebulizer (n = 45; 19%), or systemic corticosteroids (n = 28; 12%). The relative risk of a serious outcome was significantly increased in persons aged ≥75 years (vs 60–64 years) and in those with chronic obstructive pulmonary disease or congestive heart failure. The average seasonal incidence was 139 cases/10 000, and it was significantly higher in persons with cardiopulmonary disease compared with others (rate ratio, 1.89; 95% confidence interval, 1.44–2.48).

Conclusions

RSV causes substantial outpatient illness with lower respiratory tract involvement. Serious outcomes are common in older patients and those with cardiopulmonary disease.

Respiratory syncytial virus-associated illness in adults with advanced chronic obstructive pulmonary disease and/or congestive heart failure

BACKGROUND

Respiratory syncytial virus (RSV) is recognized as a serious pathogen in people with chronic cardiopulmonary conditions. Immunoprophylaxis might be considered for adults at high-risk for frequent and severe RSV infection. Thus, we studied the incidence of RSV-related medically attended acute respiratory illness (MARI) in adults with severe chronic obstructive pulmonary disease (COPD) and/or congestive heart failure (CHF).

METHODS

Subjects ≥50 years of age with Gold Class III/IV COPD and/or American Heart Association class III/IV CHF and exposure to children ≥once per month were recruited. Subjects were evaluated over 1.5 to 2.5 years for RSV-associated MARI, defined as polymerase chain reaction (PCR) and/or seroresponse.

RESULTS

Four hundred forty-five subjects were enrolled between October 2011 and May 2012. Overall, 99 RSV infections were documented by PCR or serology for a cumulative incidence of 22.2%. Of these, 42 (9.4%) subjects had protocol-specified RSV-MARI for an incidence of 4.68/100 patient-seasons. All-cause MARI was common (63.85/100 patient-seasons) with rhinovirus most commonly identified.

CONCLUSION

RSV infection was common in adults with severe COPD and/or advanced CHF. Given the severity of underlying cardiopulmonary diseases in the study population, most illnesses were surprisingly mild. Thus, active immunization rather than passive immunoprophylaxis with monoclonal antibodies may be a more cost-effective strategy.

Case study-based time-course analysis of symptoms of respiratory syncytial virus infections followed by acute sinusitis in otherwise-healthy adults

Reports on respiratory syncytial virus (RSV) infections are abundant in pediatric and geriatric populations but not many in healthy adults, and particularly, those which demonstrated the illness throughout its time course are rare. We report two otherwise-healthy adult cases, showing a number of evidence essential for confirmation of exclusive infections with RSV, and document their clinical features from the onset of the disease to recovery, including secondary sinusitis with magnetic resonance (MR) and computed tomography (CT) images. The infection was proven by isolating RSV belonging to subgroup B and by observing elevated anti-RSV antibody titer in the paired sera. Possible contribution of other pathogens including almost all respiratory viruses and representative bacteria, was excluded by negative results in multiplex PCR examination. In the first case, illness initiated with pharyngeal pain, followed by symptoms of sneezing, severe rhinorrhea and coughing, which peaked at approximately 5-7 days and persisted for 12 days. The patient experienced a slight chill, but the body temperature did not exceed 37 °C during illness. The patient showed no significant finding but only a slight increase in serum C-reactive protein level in the routine clinical laboratory examinations. On the 9th day of illness, a dull headache started persisting for at least a week after which it gradually waned. Sinusitis was found by chance on MR images of maxillary sinus 8 days after the headache started, and the finding disappeared on CT images taken after 6 months. In the second case, the symptoms included severe rhinorrhea and dull facial pain around the upper nose; the pain also occurred on the 9th day of illness and the symptom was clinically diagnosed to be acute sinusitis during a visit to a physician.

Respiratory syncytial virus infection in elderly adults

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infections in infants and young children. Reinfections are common throughout adult life with more severe presentations occurring in immunocompromised individuals, subjects with underlying high-risk cardiopulmonary diseases, and in the elderly. There is now a significant body of literature indicating that the impact of RSV in elderly adults is similar to that of non-pandemic influenza, both in the community and in nursing homes. Clinical manifestations of RSV infections are similar to those caused by other viral respiratory pathogens, including influenza viruses. Molecular tests (reverse transcription-PCR) now provide a rapid diagnosis. The sputum sample combined with nasopharyngeal swab increases the diagnostic yield. At the present time, treatment is mainly symptomatic. The prevention of RSV consists in various infection control strategies, such as standard precautions, especially hand washing and droplet precautions to limit the nosocomial spread. Vaccines and antiviral agents for the prevention and treatment of RSV infections in elderly adults are currently not available, but they are being developed.

Mixed viral infections of the respiratory tract; an epidemiological study during consecutive winter seasons

The current study aimed to describe the molecular epidemiology of mixed respiratory viral infections during consecutive winter seasons in a tertiary care hospital. Patients with symptoms of respiratory tract infection were evaluated during the 2009‐2011 and 2013‐15 winter seasons. A clinical microarray technique was used for viral detection. Clinical and epidemiological data were correlated with mixed viral detection and the need for hospitalization. In 332 out of 604 (54.4%) evaluated patients (17.6% children) a respiratory virus was identified. Mixed viral infections were diagnosed in 68/332 (20.5%) patients with virus detection (66.2% mixed Influenza‐RSV infections). Mixed viral infections were more commonly detected in children (OR 3.7; 95%CI 1.9‐5.6, P < 0.01) and patients with comorbidities. In logistic regression analyses, mixed viral infections were associated with younger age (mean age 30.4 years vs. 41.8 years, P ≤ 0.001) and increased rates of fever (OR: 2.7; 95%CI 1.04‐7.2, P < 0.05) but no adverse outcomes or increased rates of hospitalization. High rates of mixed viral infections were noted during all winter seasons (especially Influenza and RSV) and were more common in younger patients. The clinical significance of mixed respiratory viral infection needs further elucidation.

Survey of diagnostic testing for respiratory syncytial virus (RSV) in adults: Infectious disease physician practices and implications for burden estimates

Respiratory syncytial virus (RSV) often causes respiratory illness in adults. Over 40 RSV vaccine and monoclonal antibody products are currently in preclinical development or clinical trials. Because RSV diagnostic practices may impact disease burden estimates, we investigated infectious disease physicians' RSV diagnostic practices among their adult patients.

The impact of virus infections on pneumonia mortality is complex in adults: a prospective multicentre observational study

Background

Various viruses are known to be associated with pneumonia. However, the impact of viral infections on adult pneumonia mortality remains unclear. This study aimed to clarify the effect of virus infection on pneumonia mortality among adults stratified by virus type and patient comorbidities.

Methods

This multicentre prospective study enrolled pneumonia patients aged ≥15 years from September 2011 to August 2014. Sputum samples were tested by in-house multiplex polymerase chain reaction assays to identify 13 respiratory viruses. Viral infection status and its effect on in-hospital mortality were examined by age group and comorbidity status.

Results

A total of 2617 patients were enrolled in the study and 77.8% was aged ≥65 years. 574 (21.9%) did not have comorbidities, 790 (30.2%) had chronic respiratory disease, and 1253 (47.9%) had other comorbidities. Viruses were detected in 605 (23.1%) patients. Human rhinovirus (9.8%) was the most frequently identified virus, followed by influenza A (3.9%) and respiratory syncytial virus (3.9%). Respiratory syncytial virus was more frequently identified in patients with chronic respiratory disease (4.7%) than those with other comorbidities (4.2%) and without comorbidities (2.1%) (p = 0.037). The frequencies of other viruses were almost identical between the three groups. Virus detection overall was not associated with increased mortality (adjusted risk ratio (ARR) 0.76, 95% CI 0.53–1.09). However, influenza virus A and B were associated with three-fold higher mortality in patients with chronic respiratory disease but not with other comorbidities (ARR 3.38, 95% CI 1.54–7.42). Intriguingly, paramyxoviruses were associated with dramatically lower mortality in patients with other comorbidities (ARR 0.10, 95% CI 0.01–0.70) but not with chronic respiratory disease. These effects were not affected by age group.

Conclusions

The impact of virus infections on pneumonia mortality varies by virus type and comorbidity status in adults.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2858-y) contains supplementary material, which is available to authorized users.

Respiratory Syncytial Virus Infection Control Challenges with a Novel Polymerase Chain Reaction Assay in a Tertiary Medical Center

OBJECTIVES To evaluate host characteristics, mode of infection acquisition, and infection control procedures in patients with a positive respiratory syncytial virus (RSV) test result after the introduction of the GenXpert Influenza/RSV polymerase chain reaction (PCR) assay. DESIGN Retrospective cohort study. PATIENTS Adults with a positive PCR test result for RSV who were hospitalized in a tertiary academic medical center between January 2015 and December 2016 were included in this study. Our infection control policy applies contact isolation precautions only for immunocompromised patients. METHODS Patients were identified through 2 databases, 1 consisting of patients isolated because of RSV infection and 1 with automatically collected laboratory results. Baseline and clinical characteristics were collected through a retrospective medical chart review. The rate of and clinical factors associated with healthcare-associated RSV infections were evaluated. RESULTS In total, 108 episodes in 106 patients hospitalized with a positive Xpert RSV test result were recorded during the study period. Among them, 11 episodes were healthcare-associated infections (HAIs) and 97 were community-acquired infections (CAIs). The mean length of hospital stay (LOS, 40.2 vs 11.2 days), the mean number of room switches (3.5 vs 1.7) and ward switches (1.5 vs 0.4), and the mean numbers of contact patients (9.9 vs 3.8) were significantly longer and higher in the HAI group than in the CAI group (P<.0001). Surveillance of microbiology records and clinical data did not reveal evidence for a cluster or an epidemic during the 2-year observation period. CONCLUSIONS The introduction of a rapid molecular diagnostic test systematically applied to patients with influenza-like illness may challenge current infection control policies. In our study, patients with HAIs had a prolonged hospital stay and a high number of contact patients, and they switched rooms and wards frequently. Infect Control Hosp Epidemiol 2017;38:1291-1297.