Seasonal incidence of medically attended respiratory syncytial virus infection in a community cohort of adults ≥50 years old

Estimating the Undetected Burden of Respiratory Syncytial Virus Hospitalizations in Adults Through Capture-Recapture Methods

INTRODUCTION

Traditional surveillance systems may underestimate the burden caused by respiratory syncytial virus (RSV). Capture-recapture methods provide alternatives for estimating the number of RSV-related hospitalizations in a population.

METHODS

Capture-recapture methods were used to estimate the number of RSV-related hospitalizations in adults in Middle Tennessee from two independent hospitalization surveillance systems during consecutive respiratory seasons from 2016-2017 to 2019-2020. Data from the Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN) and the Emerging Infections Program (EIP) were used. Annual RSV hospitalization rates were calculated using the capture-recapture estimates weighted by hospitals' market share divided by the corresponding census population.

RESULTS

Using capture-recapture methods, the estimated overall adult hospitalization rates varied from 8.3 (95% CI: 5.9-15.4) RSV-related hospitalizations per 10,000 persons during the 2016-2017 season to 28.4 (95% CI: 18.2-59.0) hospitalizations per 10,000 persons in the 2019-2020 season. The proportion of hospitalizations that HAIVEN determined ranged from 8.7% to 36.7% of the total capture-recapture estimated hospitalization, whereas EIP detected 23.5% to 52.7% of the total capture-recapture estimated hospitalizations.

CONCLUSION

Capture-recapture estimates showed that individual traditional surveillance systems underestimated the hospitalization burden in adults. Using capture-recapture allows for a more comprehensive estimate of RSV hospitalizations.

The disease burden of respiratory syncytial virus in older adults

PURPOSE OF REVIEW

To highlight the respiratory syncytial virus (RSV) disease burden and the current developments and challenges in RSV prevention for older adults ≥60 years through analysis of RSV epidemiology and the effectiveness of emerging vaccines.

RECENT FINDINGS

In industrialized countries, RSV incidence rates and hospitalization rates among older adults are estimated to be 600.7 cases per 100 000 person-years and 157 hospitalizations per 100 000 person-years, respectively. Yet, accurately determining RSV morbidity and mortality in older adults is challenging, thus resulting in substantially under-estimating the disease burden. The in-hospital fatality rates vary substantially with age and geographies, and can be as high as 9.1% in developing countries. Two promising RSV vaccines for the elderly have been approved, demonstrating efficacies of up to 94.1%, signifying considerable advancement in RSV prevention. However, concerns over potential side effects remain.

SUMMARY

RSV is associated with a significant burden in older adults. While the landscape of RSV prevention in older adults is promising with the licensure of vaccines from two companies, current trial data underscore the need for additional studies. Addressing the real-world effectiveness of these vaccines, understanding potential rare side effects, and ensuring broad inclusivity in future trials are crucial steps to maximize their potential benefits.

Estimated Incidence of Hospitalizations and Deaths Attributable to Respiratory Syncytial Virus Infections Among Adults in Germany Between 2015 and 2019

INTRODUCTION

Respiratory syncytial virus (RSV) burden in adults is underestimated mainly due to unspecific symptoms and limited standard-of-care testing. We estimated the population-based incidence of hospitalization and mortality attributable to RSV among adults with and without risk factors in Germany.

METHODS

Weekly counts of hospitalizations and deaths for respiratory, cardiovascular, and cardiorespiratory diseases were obtained (Statutory Health Insurance database, 2015-2019). A quasi-Poisson regression model was fitted to estimate the number of hospitalizations and deaths attributable to RSV as a function of periodic and aperiodic time trends, and viral activity while allowing for potential overdispersion. Weekly counts of RSV and influenza hospitalizations in children < 2 years and adults ≥ 60 years, respectively, were used as viral activity indicators. Models were stratified by age group and risk status (defined as presence of selected comorbidities).

RESULTS

Population-based RSV-attributable hospitalization incidence rates were high among adults ≥ 60 years: respiratory hospitalizations (236-363 per 100,000 person-years) and cardiorespiratory hospitalizations (584-912 per 100,000 person-years). RSV accounted for 2-3% of all cardiorespiratory hospitalizations in this age group. The increase in cardiorespiratory hospitalization risk associated with underlying risk factors was greater in 18-44 year old persons (five to sixfold higher) than in ≥ 75 year old persons (two to threefold higher).

CONCLUSIONS

This is a first model-based study to comprehensively assess adult RSV burden in Germany. Estimated cardiorespiratory RSV hospitalization rates increased with age and were substantially higher in people with risk factors compared to those without risk factors. Our study indicates that RSV, like other respiratory viruses, contributes to both respiratory and cardiovascular hospitalizations. Effective prevention strategies are needed, especially among older adults ≥ 60 years and among adults with underlying risk factors.

Psychometric evaluation of the respiratory syncytial virus infection, intensity and impact questionnaire (RSV-iiiQ) in adults

BACKGROUND

Despite a number of respiratory syncytial virus (RSV) vaccine candidates being tested in clinical trials, disease-specific, self-reported instruments assessing symptom severity of RSV infection from the perspective of adult patients are still needed. The RSV Infection, Intensity and Impact Questionnaire (RSV-iiiQ) was adapted from the Influenza Intensity and Impact Questionnaire (FluiiQ™). This study evaluated some measurement properties of the RSV-iiiQ.

METHODS

Data were collected in a web-based survey over two consecutive days. Participants completed the RSV-iiiQ, the Patient Global Impression of Severity, Sheehan Disability Scale, Patient Global Impression of Change, EQ-5D-5L, and a demographic questionnaire. Test-retest reliability, internal consistency, construct validity, and responsiveness of the RSV-iiiQ scales were assessed.

RESULTS

111 adults with RSV were enrolled and self-reported a variety of symptoms across the range of disease severity via a web-based platform. The RSV-iiiQ scales demonstrated satisfactory test-retest reliability, construct validity, and discriminating ability. One-factor confirmatory factor analyses confirmed that each of the four scales was sufficiently unidimensional, and internal consistencies indicated that the computation of RSV-iiiQ scale scores was plausible. Correlation-based analyses provided support for the construct validity of the RSV-iiiQ scores, and known groups analyses supported discriminating ability. Estimates of responsiveness of the scale scores were also satisfactory.

CONCLUSIONS

RSV infection is highly symptomatic and causes significant disease burden, and self-report instruments assessing symptom severity and impact are important for evaluation of new treatments. This study describes the preliminary psychometric properties of the RSV-iiiQ and indicates this tool may be useful for the assessment of the severity of symptoms and impact of acute RSV infection in adults. The findings also indicated two items, Runny nose and Ear pain, may be unnecessary and should be revisited using item response theory analysis with a larger sample size.

The respiratory syncytial virus prefusion F protein vaccine attenuates the severity of respiratory syncytial virus-associated disease in breakthrough infections in adults ≥60 years of age

Background

Respiratory syncytial virus (RSV) is a contagious pathogen causing acute respiratory infections (ARIs). Symptoms range from mild upper respiratory tract infections to potentially life-threatening lower respiratory tract disease (LRTD). In adults ≥60 years old, vaccine efficacy of a candidate vaccine for older adults (RSVPreF3 OA) was 71.7% against RSV-ARI and 82.6% against RSV-LRTD (AReSVi-006/NCT04886596). We present the patient-reported outcomes (PROs) from the same trial at the end of the first RSV season in the northern hemisphere (April 2022).

Methods

In this phase 3 trial, adults aged ≥60 years were randomized (1:1) to receive one dose of RSVPreF3 OA vaccine or placebo. PROs were assessed using InFLUenza Patient-Reported Outcome (FLU-PRO), Short Form-12 (SF-12), and EuroQol-5 Dimension (EQ-5D) questionnaires. Peak FLU-PRO Chest/Respiratory scores during the first 7 days from ARI episode onset were compared using a Wilcoxon test. Least squares mean (LSMean) of SF-12 physical functioning (PF) and EQ-5D health utility scores were estimated using mixed effects models.

Results

In the RSVPreF3 OA group (N = 12,466), 27 first RSV-ARI episodes were observed versus 95 in the Placebo group (N = 12,494). Median peak FLU-PRO Chest/Respiratory scores were lower in RSVPreF3 OA (1.07) versus Placebo group (1.86); p = 0.0258. LSMean group differences for the PF and EQ-5D health utility score were 7.00 (95% confidence interval [CI]: -9.86, 23.85; p = 0.4125) and 0.0786 (95% CI: -0.0340, 0.1913; p = 0.1695).

Conclusions

The RSVPreF3 OA vaccine, in addition to preventing infection, attenuated the severity of RSV-associated symptoms in breakthrough infections, with trends of reduced impact on PF and health utility.

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).

Peripheral Blood and Nasopharyngeal Swab MiRNA-155 Expression in Infants with Respiratory Syncytial Virus Infection

INTRODUCTION

MicroRNA (miR) 155 has been implicated in the regulation of innate and adaptive immunity as well as antiviral responses, but its role during respiratory syncytial virus (RSV) infections is not known. The objective of this study was to investigate the expression of miR-155 using pharyngeal swabs and peripheral blood in infants with RSV infection and uninfected controls.

METHODS

A prospective age-matched study was conducted in primary care in Torino from 1 August 2018 to 31 January 2020. We enrolled 66 subjects, 29 of them patients with RSV infection and 37 age-matched uninfected controls, and collected pharyngeal swabs and peripheral blood in order to assess miR-155 expression with real-time stem-loop-TaqMan real-time PCR.

RESULTS

The data show that there is no correlation between pharyngeal swabs and peripheral blood with respect to miR-155 expression. The 1/ΔCq miR-155 expression levels in throat swabs in RSV bronchiolitis patients and healthy controls were 0.19 ± 0.11 and 0.21 ± 0.09, respectively, and were not significantly different between healthy controls and bronchiolitis (p = 0.8414). In the peripheral blood, miR-155 levels were higher than those of healthy control subjects: 0.1 ± 0.013 and 0.09 ± 0.0007, respectively; p = 0.0002.

DISCUSSION

Our data provide evidence that miR-155 expression is higher in peripheral blood during RSV infection but not in swabs. This difference in the timing of sample recruitment could explain the differences obtained in the results; miR-155 activation is probably only assessable in the very early stages of infection in the swab and remains visible for longer in the blood. New investigations are needed in order to clarify whether the miR-155 expression in swabs can be influenced by different stages of virus disease of infants.

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.

Safety and immunogenicity of a respiratory syncytial virus prefusion F protein (RSVPreF3) candidate vaccine in older Japanese adults: A phase I, randomized, observer-blind clinical trial

BACKGROUND

Respiratory syncytial virus (RSV) causes lower respiratory tract infection, with a high burden of disease among adults ≥60 years. This study assessed the safety, reactogenicity, and immunogenicity of an investigational adjuvanted RSV vaccine (RSVPreF3/AS01_B) in Japanese adults aged 60-80 years.

METHODS

Forty participants were randomized to receive two doses of RSVPreF3/AS01_B or the placebo, in a 1:1 ratio, two months apart, in this placebo-controlled study. Solicited administration-site and systemic adverse events (AEs) were collected within 7 days and unsolicited AEs within 30 days post-vaccination. Serious AEs (SAEs) and potential immune-mediated diseases (pIMDs) were collected throughout the study (12 months post-dose 2). RSVPreF3-specific immunoglobulin G (IgG) antibody concentrations and neutralizing antibody (nAb) titers against RSV-A were evaluated on day (D)1, D31, D61, D91 and those against RSV-B on D1, D31, D91.

RESULTS

Solicited AEs were reported more frequently in RSVPreF3/AS01_B recipients (80.0%-90.0%) than in placebo recipients (10.0%-20.0%). Two RSVPreF3/AS01_B recipients experienced grade 3 solicited AEs. Rate of unsolicited AEs were similar (30.0%-35.0%) in both groups. No RSVPreF3/AS01_B recipient reported SAEs/pIMDs, while one placebo recipient reported two SAEs that were unrelated to vaccination. Baseline RSVPreF3-specific IgG and RSV-A/-B nAb levels were above the assay cut-off values. In the RSVPreF3/AS01_B group, RSVPreF3-specific IgG concentrations increased 12.8-fold on D31 and 9.2-fold on D91 versus baseline while nAb titers increased 7.3-fold (RSV-A) and 8.4-fold (RSV-B) on D31 and 6.3-fold (RSV-A) and 9.9-fold (RSV-B) on D91.

CONCLUSIONS

The RSVPreF3/AS01_B vaccine was well tolerated and immunogenic in older Japanese adults.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04090658.

Respiratory syncytial virus disease burden in adults aged 60 years and older in high-income countries: A systematic literature review and meta-analysis

BACKGROUND

Respiratory syncytial virus (RSV)-associated acute respiratory infection (ARI) is an underrecognized cause of illness in older adults. We conducted a systematic literature review and meta-analysis to estimate the RSV disease burden in adults ≥60 years in high-income countries.

METHODS

Data on RSV-ARI and hospitalization attack rates and in-hospital case fatality rates (hCFR) in adults ≥60 years from the United States, Canada, European countries, Japan, and South Korea were collected based on a systematic literature search (January 1, 2000-November 3, 2021) or via other methods (citation search, unpublished studies cited by a previous meta-analysis, gray literature, and an RSV-specific abstract booklet). A random effects meta-analysis was performed on estimates from the included studies.

RESULTS

Twenty-one studies were included in the meta-analysis. The pooled estimates were 1.62% (95% confidence interval [CI]: 0.84-3.08) for RSV-ARI attack rate, 0.15% (95% CI: 0.09-0.22) for hospitalization attack rate, and 7.13% (95% CI: 5.40-9.36) for hCFR. In 2019, this would translate into approximately 5.2 million cases, 470,000 hospitalizations, and 33,000 in-hospital deaths in ≥60-year-old adults in high-income countries.

CONCLUSIONS

RSV disease burden in adults aged ≥60 years in high-income countries is higher than previously estimated, highlighting the need for RSV prophylaxis in this age group.

Change in functional status associated with respiratory syncytial virus infection in hospitalized older adults

BACKGROUND

Respiratory syncytial virus (RSV) causes severe respiratory illnesses in infants and older adults. Older adults are frequently hospitalized with RSV illness and may experience loss of function. This study evaluated longitudinal changes in function associated with RSV hospitalization in older adults.

METHODS

Adults ≥60 years hospitalized with laboratory-confirmed RSV were enrolled (N = 302). Demographics and comorbidities were collected. Functional status was assessed 2 weeks pre-hospitalization by recall, at enrollment, hospital discharge and 2, 4, and 6 months post-discharge using the Lawton-Brody Instrumental Activities of Daily Living (IADL) (scale 0-8) and Barthel ADL Index (scale 0-100).

RESULTS

RSV-associated hospitalization resulted in acute functional loss. Median IADL (5 vs. 3, p < 0.0001) and ADL (90 vs. 70, p < 0.0001) scores decreased significantly from pre-hospitalization to admission and remained decreased at discharge. There were no statistically significant differences between pre-hospitalization and 2-, 4-, or 6-month scores. However, 33% and 32% of subjects experienced decreased 6-month IADL and ADL scores, respectively. Additionally, 14% required a higher level of care at discharge. When stratified by pre-hospitalization living situation, 6-month IADL scores declined significantly for those admitted from a skilled nursing facility (3 vs. 1, p = 0.001). In multivariate analysis, male sex and diabetes were associated with a 6-month decline in ADL score of ≥10.

CONCLUSIONS

Older adults hospitalized with RSV demonstrate acute functional decline that may become prolonged. Pre-hospitalization living situation may predict patient outcomes. Further study is needed with hospitalized age-matched controls and refined measurement tools to better define the specific impact of RSV on function.

Incidence and economic burden of respiratory syncytial virus among adults in the United States: A retrospective analysis using 2 insurance claims databases

BACKGROUND: Respiratory syncytial virus (RSV) is a common, contagious, and seasonal pathogen causing 64 million acute respiratory infections annually in adults and children worldwide. High-risk adults, including older adults and those with cardiopulmonary conditions or weakened immune systems, are more likely to be infected. However, limited information exists on RSV incidence and associated costs among adults, including high-risk patients. OBJECTIVE: To evaluate the annual incidence of medically attended, International Classification of Diseases (ICD)-coded RSV among commercially insured adults and assess health care costs among adults with ICD-coded RSV in the United States. METHODS: Optum's deidentified Clinformatics Data Mart Database (January 01, 2007, to June 30, 2020) and IBM's MarketScan Databases (January 01, 2000, to July 31, 2020) were used. Medically attended, ICD-coded RSV incidence among adults was assessed from July 1 of a given year to June 30 of the next year and reported per 100,000 population. Trends in all-cause mean weekly costs pre-RSV and post-RSV diagnosis were reported. Results were reported overall and among patients aged 60-64 years, 65 years or older, 85 years or older, and 18-59 years at high risk of severe RSV (defined as having cardiopulmonary conditions or a weakened immune system). RESULTS: Annual incidence of medically attended, ICD-coded RSV in adults overall was 22.0-52.9 in Optum and 23.4-63.6 in MarketScan. Incidence rates were higher among patients aged 60-64 years (Optum: 25.2-66.1; MarketScan: 31.9-82.1), 65 years or older (Optum: 37.3-75.5; MarketScan: 54.1-97.3), 85 years or older (Optum: 92.4-140.6; MarketScan: 79.4-234.7), and 18-59 years at high risk of severe RSV (Optum: 41.3-135.9; MarketScan: 46.3-112.4). Mean weekly costs increased during the week before (Optum: $2,325; MarketScan: $2,080) and post-RSV diagnosis (Optum: $9,523; MarketScan: $3,551), compared with those in weeks 2-8 pre-RSV diagnosis (Optum: $1,350; MarketScan: $872). The increases in mean weekly costs during the week before and the week following RSV diagnosis were higher among patients aged 60-64 years (mean weekly costs in weeks 2-8 pre-RSV, week 1 pre-RSV, week 1 post-RSV; Optum: $1,623, $2,690, $10,823; MarketScan: $1,259, $2,992, $5,069), 65 years or older (Optum: $1,731, $3,067, $12,866; MarketScan: $1,517, $3,571, $5,268), 85 years or older (Optum: $1,563, $2,430, $18,134; MarketScan: $1,613, $4,113, $6,231), and 18-59 years at high risk of severe RSV (only for MarketScan: $1,237, $3,294, $5,531; costs were similar for Optum). CONCLUSIONS: Incidence of medically attended, ICD-coded RSV in adults was 22.0-63.6 per 100,000 population, a likely underestimation since RSV was not systematically tested and only RSV-coded cases were observed. Incremental costs associated with RSV were substantial. Incidence rates and costs were higher among patients aged 60 years or older and patients at high risk of severe RSV. DISCLOSURES: This study was sponsored by Janssen Scientific Affairs, LLC. The sponsor was involved in the study design, interpretation of results, manuscript preparation, and publication decisions. B. Brookhart and D. Anderson are employees of Janssen Scientific Affairs, LLC, and are stockholders of Johnson & Johnson. C. Rossi, B. Emond, J. Wang, P. Lefebvre, and M.-H. Lafeuille are employees of Analysis Group, Inc., a consulting company that has provided paid consulting services to Janssen Scientific Affairs, LLC, which funded the development and conduct of this study and manuscript. M. Mesa-Frias. and S. Drummond are former employees of Janssen Scientific Affairs, LLC. L. Lamerato is an employee of Henry Ford Health System and received research funding from Janssen Scientific Affairs, LLC.

Rates of Medically-Attended RSV among US Adults: A Systematic Review and Meta-Analysis

Background

Adult respiratory syncytial virus (RSV) vaccines are in late stages of development. A comprehensive synthesis of adult RSV burden is needed to inform public health decision-making.

Methods

We performed a systematic review and meta-analysis of studies describing the incidence of medically-attended RSV (MA-RSV) among US adults. We also identified studies reporting nasopharyngeal (NP) or nasal swab RT-PCR results with paired serology (four-fold-rise) or sputum (RT-PCR) to calculate RSV detection ratios quantifying improved diagnostic yield after adding a second specimen type (ie, serology or sputum).

Results

We identified 14 studies with 15 unique MA-RSV incidence estimates, all based on NP or nasal swab RT-PCR testing alone. Pooled annual RSV-associated incidence per 100,000 adults ≥65 years of age was 178 (95%CI: 152‒204; n = 8 estimates) hospitalizations (4 prospective studies: 189; 4 model-based studies: 157), 133 (95%CI: 0‒319, n = 2) emergency department (ED) admissions, and 1519 (95%CI: 1109‒1929, n = 3) outpatient visits. Based on 6 studies, RSV detection was ∼1.5 times higher when adding paired serology or sputum. After adjustment for this increased yield, annual RSV-associated rates per 100,000 adults ≥65 years were 267 hospitalizations (UI: 228‒306) (prospective: 282; model-based: 236), 200 ED admissions (UI: 0‒478), and 2278 outpatient visits (UI: 1663‒2893). Persons &lt;65 years with chronic medical conditions were 1.2−28 times more likely to be hospitalized for RSV depending on risk condition.

Conclusions

The true burden of RSV has been underestimated and is significant among older adults and individuals with chronic medical conditions. A highly effective adult RSV vaccine would have substantial public-health impact.

Repeated-Dose Toxicity, Biodistribution, and Shedding Assessments With a ChAd155 Respiratory Syncytial Virus Vaccine Candidate Evaluated in Rabbits and Rats

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infections (LRTI) in infants, and toddlers and vaccines are not yet available. A pediatric RSV vaccine (ChAd155-RSV) is being developed to protect infants against RSV disease. The ChAd155-RSV vaccine consists of a recombinant replication-deficient chimpanzee-derived adenovirus (ChAd) group C vector engineered to express the RSV antigens F, N, and M2-1. The local and systemic effects of three bi-weekly intramuscular injections of the ChAd155-RSV vaccine was tested in a repeated-dose toxicity study in rabbits. After three intramuscular doses, the ChAd155-RSV vaccine was considered well-tolerated. Changes due to the vaccine-elicited inflammatory reaction/immune response were observed along with transient decreases in platelet count without physiological consequences, already reported for other adenovirus-based vaccines. In addition, the biodistribution and shedding of ChAd155-RSV were also characterized in two studies in rats. The distribution and persistence of the ChAd155-RSV vaccine candidate was consistent with other similar adenovector-based vaccines, with quantifiable levels of ChAd155-RSV observed at the injection site (muscle) and the draining lymph nodes up to 69 days post administration. The shedding results demonstrated that ChAd155-RSV was generally not detectable in any secretions or excreta samples. In conclusion, the ChAd155-RSV vaccine was well-tolerated locally and systemically.

Evaluating the Individual Healthcare Costs and Burden of Disease Associated with RSV Across Age Groups

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of acute respiratory infection (ARI), with high morbidity and mortality worldwide. RSV costing and burden estimates can highlight the potential benefits of future vaccination programs and are essential for economic evaluations.

OBJECTIVE

We aimed to determine RSV healthcare costs across age groups and the overall disease burden of medically attended RSV in Canada.

METHODS

We conducted a retrospective case-control study to estimate the attributable healthcare costs per RSV case in Alberta. We used two case definitions to capture diversity in case severity: laboratory-confirmed RSV and ARI attributable to RSV. Matching occurred on five criteria: (1) age, (2) urban/rural status, (3) sex, (4) prematurity and (5) Charlson Comorbidity Index score. We calculated the age-specific burden of medically attended RSV in Canada from 2010 to 2019 by multiplying the weekly age-specific incidence of medically attended ARI with the RSV positivity rate.

RESULTS

Costs per laboratory-confirmed RSV case were (in Canadian dollars [CAD], year 2020 values) $CAD12,713 and 40,028 in the first 30 and 365 days following diagnosis, respectively, whereas a case of ARI potentially attributable to RSV cost $CAD316 and 915, in 30 and 365 days, respectively. Older (aged ≥ 65 years) and younger (aged < 90 days) age groups had the highest case costs. The average medically attended RSV incidence rate across nine seasons was 1743 cases per 100,000 people per year.

CONCLUSIONS

RSV is a common and expensive infection at the extremes of life, and the development of immunization programs targeting older and younger ages may be important for the reduction of RSV burden and cost.

Evaluating the Increased Burden of Cardiorespiratory Illness Visits to Adult Emergency Departments During Flu and Bronchiolitis Outbreaks in the Pediatric Population: Retrospective Multicentric Time Series Analysis

BACKGROUND

Cardiorespiratory decompensation (CRD) visits have a profound effect on adult emergency departments (EDs). Respiratory pathogens like respiratory syncytial virus (RSV) and influenza virus are common reasons for increased activity in pediatric EDs and are associated with CRD in the adult population. Given the seasonal aspects of such challenging pathology, it would be advantageous to predict their variations.

OBJECTIVE

The goal of this study was to evaluate the increased burden of CRD in adult EDs during flu and bronchiolitis outbreaks in the pediatric population.

METHODS

An ecological study was conducted, based on admissions to the adult ED of the Centre Hospitalier Universitaire (CHU) of Grenoble and Saint Etienne from June 29, 2015 to March 22, 2020. The outbreak periods for bronchiolitis and flu in the pediatric population were defined with a decision-making support tool, PREDAFLU, used in the pediatric ED. A Kruskal-Wallis variance analysis and a Spearman monotone dependency were performed in order to study the relationship between the number of adult ED admissions for the International Classification of Diseases (ICD)-10 codes related to cardiorespiratory diagnoses and the presence of an epidemic outbreak as defined with PREDAFLU.

RESULTS

The increase in visits to the adult ED for CRD and the bronchiolitis and flu outbreaks had a similar distribution pattern (CHU Saint Etienne: χ²₃=102.7, P<.001; CHU Grenoble: χ²₃=126.67, P<.001) and were quite dependent in both hospital settings (CHU Saint Etienne: Spearman ρ=0.64; CHU Grenoble: Spearman ρ=0.71). The increase in ED occupancy for these pathologies was also significantly related to the pediatric respiratory infection outbreaks. These 2 criteria gave an idea of the increased workload in the ED due to CRD during the bronchiolitis and flu outbreaks in the pediatric population.

CONCLUSIONS

This study established that CRD visits and bed occupancy for adult EDs were significantly increased during bronchiolitis and pediatric influenza outbreaks. Therefore, a prediction tool for these outbreaks such as PREDAFLU can be used to provide early warnings of increased activity in adult EDs for CRD visits.

Rates of respiratory syncytial virus (RSV)-associated hospitalization among adults with congestive heart failure—United States, 2015–2017

Background

Respiratory syncytial virus (RSV) can cause severe disease in adults with cardiopulmonary conditions, such as congestive heart failure (CHF). We quantified the rate of RSV-associated hospitalization in adults by CHF status using population-based surveillance in the United States.

Methods

Population-based surveillance for RSV (RSV-NET) was performed in 35 counties in seven sites during two respiratory seasons (2015–2017) from October 1–April 30. Adults (≥18 years) admitted to a hospital within the surveillance catchment area with laboratory-confirmed RSV identified by clinician-directed testing were included. Presence of underlying CHF was determined by medical chart abstraction. We calculated overall and age-stratified (<65 years and ≥65 years) RSV-associated hospitalization rates by CHF status. Estimates were adjusted for age and the under-detection of RSV. We also report rate differences (RD) and rate ratios (RR) by comparing the rates for those with and without CHF.

Results

2042 hospitalized RSV cases with CHF status recorded were identified. Most (60.2%, n = 1230) were ≥65 years, and 28.3% (n = 577) had CHF. The adjusted RSV hospitalization rate was 26.7 (95% CI: 22.2, 31.8) per 10,000 population in adults with CHF versus 3.3 (95% CI: 3.3, 3.3) per 10,000 in adults without CHF (RR: 8.1, 95% CI: 6.8, 9.7; RD: 23.4, 95% CI: 18.9, 28.5). Adults with CHF had higher rates of RSV-associated hospitalization in both age groups (<65 years and ≥65 years). Adults ≥65 years with CHF had the highest rate (40.5 per 10,000 population, 95% CI: 35.1, 46.6).

Conclusions

Adults with CHF had 8 times the rate of RSV-associated hospitalization compared with adults without CHF. Identifying high-risk populations for RSV infection can inform future RSV vaccination policies and recommendations.

Assessment of interferon gamma and indoleamine 2,3-dioxygenase 1 analysis during respiratory syncytial virus infection in infants in Italy: an observational case-control study

OBJECTIVES

The aim of this study was to measure interferon gamma (IFN-γ) and indoleamine 2,3-dioxygenase 1 (IDO1) values in the White blood cells of infants during respiratory tract infections and to compare these with healthy age-matched controls.

DESIGN

This was a prospective, observational case-control study conducted in 2019-2020.

SETTING

The study took place at Regina Margherita Children's Hospital, Turin, Italy.

PARTICIPANTS

The study comprised 63 infants, including 26 patients hospitalised for bronchiolitis due to a respiratory syncytial virus (RSV) infection and 37 age-matched controls. The inclusion criteria included a positive RSV test for an infant with bronchiolitis.

METHODS

We collected peripheral blood and measured the relative quantification of messenger RNA (mRNA) expression of IFN-γ and IDO1 with TaqMan real-time PCR amplification. The data were collected on the first day of admission.

RESULTS

The mean age of the 26 patients with RSV bronchiolitis (53.8% female) was 85 (9-346) days when they were admitted to the hospital. Their mean gestational age at birth was 38 weeks and their mean birth weight was 3100 (2780-3730) g. The expression of IFN-γ was significantly reduced in patients with bronchiolitis RSV compared with healthy controls (p=0.0132). However, there was no significant difference between the two groups when the IDO1 mRNA expression values in their WCC were measured (p=0.0642).

CONCLUSION

Our findings did not clarify whether IDO1 expression was related to the early stage of the disease or to the young age of the infants. The data provide evidence that IFN-γ was significantly reduced in infants with bronchiolitis due to RSV, compared with age-matched healthy controls, but the IDO1 was not different. New investigations that focus on subjects infected with RSV at different stages of infancy would help to clarify whether IDO1 expression can be related to age.

Impact of respiratory syncytial virus disease on quality of life in adults aged ≥50 years: A qualitative patient experience cross-sectional study

Background

Information about the impact of respiratory syncytial virus (RSV) on quality of life in older adults is limited. This study characterized the patient experience of RSV illness in USA older adults and assessed the content validity of the InFLUenza Patient Reported Outcome (FLU‐PRO) in this population.

Methods

This qualitative, non‐interventional, cross‐sectional study included hybrid concept elicitation and cognitive debriefing interviews with 30 individuals (age ≥50 years) with polymerase chain reaction‐confirmed RSV diagnosed within 6 months of screening. Targeted literature review was first conducted to inform the development of interview materials. Webcam or telephone interviews were conducted by qualitative researchers using a semistructured interview guide. Interview transcripts were coded and analyzed using Excel and NVivo software.

Results

All participants reported impacts on daily activities, social activities, and relationships during RSV disease. Physical functioning was impaired in 25 (83%) participants, and 18 (60%) reported not engaging in leisure activities/hobbies. All nine participants who were working reported major impacts on work. Most (n = 28; 93%) described emotional impacts. A majority (n = 19; 63%) reported symptoms lasting beyond the acute disease stage from a week to >1 month. Symptom concepts reported generally matched FLU‐PRO items and domains. Cognitive debriefing indicated that FLU‐PRO was easy to understand and captured participants' experiences of RSV illness.

Conclusions

This study indicates that RSV disease in adults aged ≥50 years in the USA has substantial impacts on daily life and that the concepts included in FLU‐PRO are appropriate and fit for purpose as a measure of RSV symptoms in this population.

Respiratory syncytial virus infection among adults after hematopoietic stem cell transplantation

Introduction:

Respiratory syncytial virus (RSV) is a common cause of morbidity among hematopoietic stem cell transplant (HSCT) recipients, with RSV-associated lower respiratory tract infection carrying high mortality rates. There have been no large studies till date, describing the incidence, clinical features, and outcomes of RSV infection among adult HSCT recipients in India.

Methods:

A prospective cohort of 100 adults who underwent HSCT was followed up for a maximum period of 18 months starting from the date of transplantation for any episode of respiratory tract infectious disease (RTID). Respiratory samples were collected for laboratory confirmation of the presence and subtyping of RSV by real-time reverse transcriptase-polymerase chain reaction.

Results:

The study population comprised of 66% (66/100) males and 34% (34/100) females. Autologous HSCT recipients constituted 78% (78/100) and allogeneic HSCT recipients constituted 22% (22/100) of the study population. The incidence of RSV-RTID among adults after HSCT was 0.82/100 patient months. Most cases occurred during the winter season and the predominant subtype was RSV-A (9/11, 81.8%). Lower RTID was the most common clinical diagnosis made at presentation (9/11, 81.8%). Female gender was predictive of RSV-RTID (log rank P = 0.002). All the RSV-RTID episodes recovered completely without targeted therapy.

Conclusion:

RSV is a significant cause of morbidity among adult HSCT recipients in India. Prophylaxis and treatment measures need to be instituted after a proper risk-benefit assessment. Longitudinal studies with larger sample sizes are needed to confirm these results.

Clinical and economic outcomes associated with respiratory syncytial virus vaccination in older adults in the United States

BACKGROUND

Respiratory syncytial virus (RSV) is an important cause of lower respiratory infections and hospitalizations among older adults. We aimed to estimate the potential clinical benefits and economic value of RSV vaccination of older adults in the United States (US).

METHODS

We developed an economic model using a decision-tree framework to capture outcomes associated with RSV infections in US adults aged ≥ 60 years occurring during one RSV season for a hypothetical vaccine versus no vaccine. Two co-base-case epidemiology sources were selected from a targeted review of the US literature: a landmark study capturing all RSV infections and a contemporary study reporting medically attended RSV that also distinguishes mild from moderate-to-severe disease. Both base-case analyses used recent data on mortality risk in the year after RSV hospitalizations. Direct medical costs and quality-adjusted life-years (QALYs) lost per case were obtained from the literature and publicly available sources. Model outcomes included the population-level clinical and economic RSV disease burden among older adults, potential vaccine-avoidable disease burden, and the potential value-based price of a vaccine from a third-party payer perspective.

RESULTS

Our two base-case analyses estimated that a vaccine with 50% efficacy and coverage matching that of influenza vaccination would prevent 43,700-81,500 RSV hospitalizations and 8,000-14,900 RSV-attributable deaths per RSV season, resulting in 1,800-3,900 fewer QALYs lost and avoiding $557-$1,024 million. Value-based prices for the co-base-case analyses were $152-$299 per vaccination at a willingness to pay of $100,000/QALY gained. Sensitivity analyses found that the economic value of vaccination was most sensitive to RSV incidence and increased posthospitalization mortality risks.

CONCLUSIONS

Despite variability and gaps in the epidemiology literature, this study highlights the potential value of RSV vaccination for older adults in the US. Our analysis provides contemporary estimates of the population-level RSV disease burden and insights into the economic value drivers for RSV vaccination.

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.

Incidence of Medically Attended Acute Respiratory Illnesses Due to Respiratory Viruses Across the Life Course During the 2018/19 Influenza Season

Background

While multiple respiratory viruses circulate in humans, few studies have compared the incidence of different viruses across the life course. We estimated the incidence of outpatient illness due to 12 different viruses during November 2018 through April 2019 in a fully enumerated population.

Methods

We conducted active surveillance for ambulatory care visits for acute respiratory illness (ARI) among members of Kaiser Permanente Washington (KPWA). Enrolled patients provided respiratory swab specimens which were tested for 12 respiratory viruses using RT-PCR. We estimated the cumulative incidence of infection due to each virus overall and by age group.

Results

The KPWA population under surveillance included 202,562 individuals, of whom 2,767 (1.4%) were enrolled in the study. Influenza A(H3N2) was the most commonly detected virus, with an overall incidence 21 medically attended illnesses per 1,000 population; the next most common viruses were influenza A(H1N1) (18 per 1,000), coronaviruses (13 per 1,000), respiratory syncytial virus (RSV, 13 per 1,000), and rhinovirus (9 per 1,000). RSV was the most common cause of medically attended ARI among children aged 1-4 years; coronaviruses were the most common among adults aged ≥65 years.

Conclusions

Consistent with other studies focused on single viruses, we found that influenza and RSV were major causes of acute respiratory illness in persons of all ages. In comparison, coronaviruses and rhinovirus were also important pathogens. Prior to the emergence of SARS-CoV-2, coronaviruses were the second-most common cause of medically attended ARI during the 2018/19 influenza season.

Impact of public health measures on the post-COVID-19 respiratory syncytial virus epidemics in France

Since the beginning of the COVID-19 pandemic, other respiratory illnesses decreased worldwide. This study described the consequences of public health measures on respiratory syncytial virus (RSV) severe infections in France, where an interseasonal resurgence of RSV occurred recently. All patients admitted to Necker Hospital (Paris) between August 2018 and April 2021 with a diagnosis of RSV-associated acute lung respiratory infection (ALRI) were enrolled. Characteristics of subjects with RSV-associated ALRI in 2020/2021 were compared to those infected during the two previous outbreaks. Overall, 664 inpatients were diagnosed with RSV-associated ALRI: 229, 183, and 252 during the 2018/2019, 2019/2020, and 2020/2021 outbreaks, respectively. During autumn 2020, a national lockdown began in France but schools remained open. A 3-month delayed RSV epidemic occurred at the end of this lockdown. Compared to previous outbreaks, the 2020/2021 epidemics involved more children aged 6 to 11 months (25.8% versus 13.1%, p < 0.0001), but less infants aged < 6 months (41.3% versus 56.6%, p < 0.0001) and less adults (0.0 versus 2.7%, p < 0.0001). Shorter length of stay at hospital, less frequent requirement of admission to intensive care unit, use of non-invasive ventilation, and/or high-flow nasal oxygen were observed in 2020/2021 than during previous epidemics (p < 0.0001). Delayed RSV outbreak was associated with more hospitalizations for ALRI, higher age of pediatric inpatients, but milder median clinical phenotype. Reinforced public health measures (even while keeping nurseries and schools open with mandatory face masks since six years of age) could impact, at least transiently, the burden of RSV-related hospitalizations.

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.

CX3CR1 Is a Receptor for Human Respiratory Syncytial Virus in Cotton Rats

Respiratory syncytial virus (RSV) has been reported to use CX3CR1 in vitro as a receptor on cultured primary human airway epithelial cultures. To evaluate CX3CR1 as the receptor for RSV in vivo, we used the cotton rat animal model because of its high permissiveness for RSV infection. Sequencing the cotton rat CX3CR1 gene revealed 91% amino acid similarity to human CX3CR1. Previous work found that RSV binds to CX3CR1 via its attachment glycoprotein (G protein) to infect primary human airway cultures. To determine whether CX3CR1-G protein interaction is necessary for RSV infection, recombinant RSVs containing mutations in the CX3CR1 binding site of the G protein were tested in cotton rats. In contrast to wild-type virus, viral mutants did not grow in the lungs of cotton rats. When RSV was incubated with an antibody blocking the CX3CR1 binding site of G protein and subsequently inoculated intranasally into cotton rats, no virus was found in the lungs 4 days postinfection. In contrast, growth of RSV was not affected after preincubation with heparan sulfate (the receptor for RSV on immortalized cell lines). A reduction in CX3CR1 expression in the cotton rat lung through the use of peptide-conjugated morpholino oligomers led to a 10-fold reduction in RSV titers at day 4 postinfection. In summary, these results indicate that CX3CR1 functions as a receptor for RSV in cotton rats and, in combination with data from human airway epithelial cell cultures, strongly suggest that CX3CR1 is a primary receptor for naturally acquired RSV infection. IMPORTANCE The knowledge about a virus receptor is useful to better understand the uptake of a virus into a cell and potentially develop antivirals directed against either the receptor molecule on the cell or the receptor-binding protein of the virus. Among a number of potential receptor proteins, human CX3CR1 has been demonstrated to act as a receptor for respiratory syncytial virus (RSV) on human epithelial cells in tissue culture. Here, we report that the cotton rat CX3CR1, which is similar to the human molecule, acts as a receptor in vivo. This study strengthens the argument that CX3CR1 is a receptor molecule for RSV.

Update in Viral Infections in the Intensive Care Unit

The advent of highly sensitive molecular diagnostic techniques has improved our ability to detect viral pathogens leading to severe and often fatal infections that require admission to the Intensive Care Unit (ICU). Viral infections in the ICU have pleomorphic clinical presentations including pneumonia, acute respiratory distress syndrome, respiratory failure, central or peripheral nervous system manifestations, and viral-induced shock. Besides de novo infections, certain viruses fall into latency and can be reactivated in both immunosuppressed and immunocompetent critically ill patients. Depending on the viral strain, transmission occurs either directly through contact with infectious materials and large droplets, or indirectly through suspended air particles (airborne transmission of droplet nuclei). Many viruses can efficiently spread within hospital environment leading to in-hospital outbreaks, sometimes with high rates of mortality and morbidity, thus infection control measures are of paramount importance. Despite the advances in detecting viral pathogens, limited progress has been made in antiviral treatments, contributing to unexpectedly high rates of unfavorable outcomes. Herein, we review the most updated data on epidemiology, common clinical features, diagnosis, pathogenesis, treatment and prevention of severe community- and hospital-acquired viral infections in the ICU settings.

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.

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.

Global Disease Burden Estimates of Respiratory Syncytial Virus-Associated Acute Respiratory Infection in Older Adults in 2015: A Systematic Review and Meta-Analysis

Respiratory syncytial virus-associated acute respiratory infection (RSV-ARI) constitutes a substantial disease burden in older adults aged ≥65 years. We aimed to identify all studies worldwide investigating the disease burden of RSV-ARI in this population. We estimated the community incidence, hospitalization rate, and in-hospital case-fatality ratio (hCFR) of RSV-ARI in older adults, stratified by industrialized and developing regions, using data from a systematic review of studies published between January 1996 and April 2018 and 8 unpublished population-based studies. We applied these rate estimates to population estimates for 2015 to calculate the global and regional burdens in older adults with RSV-ARI in the community and in hospitals for that year. We estimated the number of in-hospital deaths due to RSV-ARI by combining hCFR data with hospital admission estimates from hospital-based studies. In 2015, there were about 1.5 million episodes (95% confidence interval [CI], .3 million-6.9 million) of RSV-ARI in older adults in industrialized countries (data for developing countries were missing), and of these, approximately 14.5% (214 000 episodes; 95% CI, 100 000-459 000) were admitted to hospitals. The global number of hospital admissions for RSV-ARI in older adults was estimated at 336 000 hospitalizations (uncertainty range [UR], 186 000-614 000). We further estimated about 14 000 in-hospital deaths (UR, 5000-50 000) related to RSV-ARI globally. The hospital admission rate and hCFR were higher for those aged ≥65 years than for those aged 50-64 years. The disease burden of RSV-ARI among older adults is substantial, with limited data from developing countries. Appropriate prevention and management strategies are needed to reduce this burden.

Titanium dioxide nanoparticles exaggerate respiratory syncytial virus-induced airway epithelial barrier dysfunction

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in children worldwide. While most develop a mild, self-limiting illness, some develop severe acute lower respiratory infection and persistent airway disease. Exposure to ambient particulate matter has been linked to asthma, bronchitis, and viral infection in multiple epidemiological studies. We hypothesized that coexposure to nanoparticles worsens RSV-induced airway epithelial barrier dysfunction. Bronchial epithelial cells were incubated with titanium dioxide nanoparticles (TiO2-NP) or a combination of TiO2-NP and RSV. Structure and function of epithelial cell barrier were analyzed. Viral titer and the role of reactive oxygen species (ROS) generation were evaluated. In vivo, mice were intranasally incubated with TiO2-NP, RSV, or a combination. Lungs and bronchoalveolar lavage (BAL) fluid were harvested for analysis of airway inflammation and apical junctional complex (AJC) disruption. RSV-induced AJC disruption was amplified by TiO2-NP. Nanoparticle exposure increased viral infection in epithelial cells. TiO2-NP induced generation of ROS, and pretreatment with antioxidant, N-acetylcysteine, reversed said barrier dysfunction. In vivo, RSV-induced injury and AJC disruption were augmented in the lungs of mice given TiO2-NP. Airway inflammation was exacerbated, as evidenced by increased white blood cell infiltration into the BAL, along with exaggeration of peribronchial inflammation and AJC disruption. These data demonstrate that TiO2-NP exposure exacerbates RSV-induced AJC dysfunction and increases inflammation by mechanisms involving generation of ROS. Further studies are required to determine whether NP exposure plays a role in the health disparities of asthma and other lung diseases, and why some children experience more severe airway disease with RSV infection.

Detection of community-acquired respiratory viruses in allogeneic stem-cell transplant recipients and controls-A prospective cohort study

Background

Community‐acquired respiratory viruses (CARV) cause upper and lower respiratory tract infections (URTI/LRTI) and may be life‐threatening for recipients of an allogeneic stem cell transplantation (allo‐SCT).

Methods

In a prospective study encompassing 4 winter‐seasons, we collected throat gargles (TG) at random time points from allo‐SCT recipients (patients) and controls and followed them up for at least 3 weeks including repetitive sampling and documentation of symptoms. A Multiplex‐PCR system to identify 20 CARV and Mycoplasma pneumoniae was used to detect CARV.

Results

One hundred ninety‐four patients with 426 TG and 273 controls with 549 TG were included. There were more patients with a positive test result (25% vs 11% in the controls), and the patients had a higher number of positive TG (70 = 16%) compared to controls (32 = 6%) (P < .001). Altogether, 115 viruses were detected. Multiple viruses in one TG (11/48, 34%) and prolonged shedding were only observed in patients (13/48, 27%). Patients had more RSV (18/83, 26%) and adenovirus (15/83, 21%) than controls (both viruses 2/32, 6%). Independent risk factors for the detection of CARV included age >40 years (OR 3.38, 95% CI 1.8‐6.4, P < .001) and presence of URTI‐symptoms (OR 3.22, 95% CI 1.9‐5.5, P < .001). No controls developed a LRTI or died whereas 4/48 (8%) patients developed a LRTI (coronavirus in 2, RSV in 1 and influenza A H1N1 in 1 patient). One patient died of CARV (influenza A H1N1).

Conclusion

Allo‐SCT‐recipients have more CARV‐infections, exhibit a different epidemiology, have more cases of co‐infection or prolonged shedding and have a higher rate of LRTI and mortality.

Delayed Diagnosis of Respiratory Syncytial Virus Infections in Hospitalized Adults: Individual Patient Data, Record Review Analysis and Physician Survey in the United States

BACKGROUND

Despite the prevalence of respiratory syncytial virus (RSV) in adults hospitalized with acute respiratory infections, guidelines for the diagnosis and management of RSV have not been established. This analysis evaluated the role and timeliness of RSV diagnostic testing and its potential impact on clinical outcomes.

METHODS

We analyzed individual patient data from hospitalized adults with confirmed RSV infections during 2 North American RSV seasons. Participating physicians reported clinical, virologic diagnosis, and outcome variables using a standardized online case form.

RESULTS

Across 32 US states, 132 physicians reported 379 RSV cases. Polymerase chain reaction-based diagnostics were the most common type of test ordered (94.2%) with <5% ordered specifically to diagnose RSV. Most tests (67.6%) were ordered in hospital wards or intensive care units. Overall, 47.4%, 30.9%, and 21.7% of patients had RSV diagnosed <12, 12‒24, and >24 hours after hospital admission, respectively. Later diagnosis was associated with longer hospital stays (n = 145; R = +0.191; P < .05) and greater antibiotic use.

CONCLUSION

Diagnosis of RSV infection in hospitalized adults is often delayed, which may affect clinical management and outcomes. Our findings indicate the need to improve the diagnostic strategies in this patient population.

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.

Preventing respiratory syncytial virus infections in hospitalized children and adults: should we do better?

Objective

To compare the burden of nosocomial and community-acquired respiratory syncytial virus (RSV)-associated acute lower respiratory tract infections (ALRIs) in adult and pediatric patients concomitantly admitted to a French tertiary hospital, and to evaluate the effectiveness of existing infection control measures.

Patients and methods

We prospectively included all adult and pediatric patients admitted to Necker hospital (Paris) between October 2018 and February 2019 with a diagnosis of RSV-associated ALRI. We compared characteristics of ALRIs between patients with community-acquired versus nosocomial infections and, in each group, between children and adults.

Results

Community-acquired and nosocomial RSV-associated ALRIs were diagnosed in 229 and 11 inpatients, respectively. The burden of community-acquired infections was higher in children than in adults: 2.1% versus 0.2% of the total number of pediatric and adult inpatients, respectively (p < 0.0001); 4.2% versus 0.2% of the total number of hospitalization days in pediatric and adult units, respectively (p < 0.0001). Compared to inpatients with community-acquired ALRIs, those with nosocomial infections were more frequently adults (45.5% versus 2.6%, p = 0.0005) and subjects with at least one chronic complex condition (100.0% versus 41.0%, p < 0.0001). The total number of hospitalization days due to nosocomial ALRIs was higher in adults than in children (0.32% versus 0.11%, p < 0.0001).

Conclusions

Nosocomial RSV-associated ALRIs rarely occurred, suggesting a good effectiveness of our infection control strategy. However, the burden of nosocomial infection was higher in adults than in children, suggesting that education and training of healthcare personnel, patients and visitors about the risk of nosocomial RSV infections should be reinforced in adult wards.

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.

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

•

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.

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.

Exchange Proteins Directly Activated by cAMP and Their Roles in Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is the leading cause of respiratory infection in young children and high-risk adults. However, a specific treatment for this viral infection is not currently available. In this study, we discovered that an exchange protein directly activated by cyclic AMP (EPAC) can serve as a potential therapeutic target for RSV. In both lower and upper epithelial cells, treatment with EPAC inhibitor (ESI-09), but not protein kinase A inhibitor (H89), significantly inhibits RSV replication and proinflammatory cytokine/chemokine induction. In addition, RSV-activated transcriptional factors belonging to the NF-κB and IRF families are also suppressed by ESI-09. Through isoform-specific gene knockdown, we found that EPAC2, but not EPAC1, plays a dominant role in controlling RSV replication and virus-induced host responses. Experiments using both EPAC2 knockout and EPAC2-specific inhibitor support such roles of EPAC2. Therefore, EPAC2 is a promising therapeutic target to regulate RSV replication and associated inflammation.IMPORTANCE RSV is a serious public health problem, as it is associated with bronchiolitis, pneumonia, and asthma exacerbations. Currently no effective treatment or vaccine is available, and many molecular mechanisms regarding RSV-induced lung disease are still significantly unknown. This project aims to elucidate an important and novel function of a protein, called EPAC2, in RSV replication and innate inflammatory responses. Our results should provide an important insight into the development of new pharmacologic strategies against RSV infection, thereby reducing RSV-associated morbidity and mortality.

Healthcare resource use and economic burden attributable to respiratory syncytial virus in the United States: a claims database analysis

Background

Despite several studies that have estimated the economic impact of Respiratory Syncytial Virus (RSV) in infants, limited data are available on healthcare resource use and costs attributable to RSV across age groups. The aim of this study was to quantify age-specific RSV-related healthcare resource use and costs on the US healthcare system.

Methods

This retrospective case-control study identified patients aged ≥1 year with an RSV event in the Truven Health Marketscan® Commercial Claims and Encounters and Medicare Supplemental and Coordination of Benefits databases between August 31, 2012 and August 1, 2013. RSV patients were matched 1:1 with non-RSV controls for age, gender, region, healthcare plan and index date (n = 11,432 in each group). Stratified analyses for healthcare resource use and costs were conducted by age groups. RSV-attributable resource use and costs were assessed based on the incremental differences between RSV cases and controls using multivariate analysis.

Results

RSV patients had a higher healthcare resource use (hospital stays, emergency room/urgent care visits, ambulatory visits and outpatient visits) than non-RSV matched controls for all age groups (all p < 0.0001), particularly in the elderly age groups with RSV (1.9 to 3 days length of stay, 0.4 to 0.5 more ER/UC visits, 0.7 to 2.7 more ambulatory visits, 12.1 to 18.6 more outpatient visits and 9.5 to 14.6 more prescriptions than elderly in the control groups). The incremental difference in adjusted mean annual costs between RSV and non-RSV controls was higher in elderly (≥65; $12,030 to $23,194) than in those aged < 65 years ($2251 to $5391). Among children, adjusted costs attributable to RSV were higher in children aged 5–17 years ($3192), than those 1–4 years ($2251 to $2521).

Conclusions

Our findings showed a substantial annual RSV-attributable healthcare resource use and costs in the US across age groups, with the highest burden in those aged ≥65 years. These data can be used in cost-effectiveness analyses, and may be useful for policymakers to guide future RSV vaccination and other prevention programs.

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.

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.

An Adjuvanted, Postfusion F Protein-Based Vaccine Did Not Prevent Respiratory Syncytial Virus Illness in Older Adults

Background

Respiratory syncytial virus (RSV) is an important cause of illness in older adults. This study assessed efficacy of a vaccine for prevention of RSV-associated acute respiratory illness (ARI), defined by specified symptoms with virologic confirmation.

Methods

This phase 2b study evaluated RSV postfusion F protein (120 µg) with glucopyranosyl lipid adjuvant (5 µg) in 2% stable emulsion. Subjects aged ≥60 years were randomly assigned at a ratio of 1:1 to receive vaccine or placebo (all received inactivated influenza vaccine). Ill subjects recorded symptoms and provided blood and nasal swab samples.

Results

In the per-protocol population (n = 1894), the incidence of RSV-associated ARI occurring ≥14 days after dosing was 1.7% and 1.6% in the vaccine and placebo groups, respectively, for a vaccine efficacy (VE) of –7.1% (90% confidence interval [CI], –106.9%–44.3%). Efficacy was not observed in secondary analyses that included seroresponse to nonvaccine RSV antigens (VE, 8.9%; 90% CI, –28.5%–35.4%) or symptoms combined with seroresponse (VE, 10.0%; 90% CI, –45.4%–44.4%). On day 29, 92.9% of vaccinees had an anti-F immunoglobulin G antibody seroresponse. Overall, 48.5% and 30.9% of RSV vaccine recipients reported local and systemic solicited symptoms, respectively.

Conclusion

The RSV vaccine was immunogenic but did not protect older adults from RSV illness.

Clinical Trials Registration

NCT02508194.

Cohort profile: the China Ageing REespiratory infections Study (CARES), a prospective cohort study in older adults in Eastern China

PURPOSE

This study was established to provide direct evidence on the incidence of laboratory-confirmed influenza virus and respiratory syncytial virus (RSV) infections in older adults in two cities in Jiangsu Province, China, and the potential impact of acute respiratory infections on frailty.

PARTICIPANTS

The cohort was enrolled in Suzhou and Yancheng, two cities in Jiangsu Province in Eastern China. Between November 2015 and March 2016, we enrolled 1532 adults who were 60-89 years of age, and collected blood samples along with baseline data on demographics, general health, chronic diseases, functional status and cognitive function through face-to-face interviews using a standardised questionnaire. Participants are being followed weekly throughout the year to identify acute respiratory illnesses. We schedule home visits to ill participants to collect mid-turbinate nasal and oropharyngeal swabs for laboratory testing and detailed symptom information for the acute illness. Regular follow-up including face-to-face interviews and further blood draws will take place every 6-12 months.

FINDINGS TO DATE

As of 3 September 2016, we had identified 339 qualifying acute respiratory illness events and 1463 (95%) participants remained in the study. Laboratory testing is ongoing.

FUTURE PLANS

We plan to conduct laboratory testing to estimate the incidence of influenza virus and RSV infections in older adults. We plan to investigate the impact of these infections on frailty and functional status to determine the association of pre-existing immune status with protection against influenza and RSV infection in unvaccinated older adults, and to assess the exposure to avian influenza viruses in this population.

Can Analysis of Routine Viral Testing Provide Accurate Estimates of Respiratory Syncytial Virus Disease Burden in Adults?

Respiratory syncytial virus (RSV) is increasingly recognized as a significant cause of adult respiratory illness. We evaluated routine viral testing and discharge diagnoses for identifying RSV and influenza burden. Polymerase chain reaction results performed in adults during emergency room visits or hospitalizations were reviewed. Peak RSV activity preceded influenza activity by 8 weeks. The ratio of total number of viral tests performed divided by total number of respiratory visits was higher during influenza than RSV peaks (1.31 vs 0.72; P = .0001). Influenza and RSV were listed primary diagnoses in 56 (30%) vs 7 (6%), respectively (P < .0001). Routine viral testing to estimate adult RSV disease burden has limitations.

The epidemiology of medically attended respiratory syncytial virus in older adults in the United States: A systematic review

Objective

This review was undertaken to assess the historical evidence of the disease incidence and burden of laboratory-confirmed respiratory syncytial virus (RSV) in medically attended older adults.

Design

A qualitative systematic literature review was performed; no statistical synthesis of the data was planned, in anticipation of expected heterogeneity across studies in this population.

Methods

A literature search of PubMed, Embase, and the Cochrane Library was conducted for studies of medically attended RSV in older adults (≥ 50 years) published in the last 15 years. Two independent reviewers screened titles and abstracts based on predefined inclusion and exclusion criteria.

Results

From 10 studies reporting incidence proportions, RSV may be the causative agent in up to 12% of medically attended acute respiratory illness in older adults unselected for comorbidities, with variations in clinical setting and by year. In multiple studies, medically attended–RSV incidence among older adults not selected for having underlying health conditions increased with increasing age. Of prospectively followed lung transplant recipients, 16% tested positive for RSV. In hospitalized adults with chronic cardiopulmonary diseases, 8% to 13% were infected with RSV during winter seasons (8%-13%) or metapneumovirus season (8%). Hospitalizations for RSV in older adults typically lasted 3 to 6 days, with substantial proportions requiring intensive care unit admission and mechanical ventilation. Among older adults hospitalized with RSV, the mortality rate was 6% to 8%.

Conclusions

Protection of older adults against RSV could reduce respiratory-related burden, especially as age increases and the prevalence of comorbidities (especially cardiopulmonary comorbidities) grows.

Characterization of Pre-F-GCN4t, a Modified Human Respiratory Syncytial Virus Fusion Protein Stabilized in a Noncleaved Prefusion Conformation

The human respiratory syncytial virus (hRSV) fusion (F) protein is considered a major target of the neutralizing antibody response to hRSV. This glycoprotein undergoes a major structural shift from the prefusion (pre-F) to the postfusion (post-F) state at the time of virus-host cell membrane fusion. Recent evidences suggest that the pre-F state is a superior target for neutralizing antibodies compared to the post-F state. Therefore, for vaccine purposes, we have designed and characterized a recombinant hRSV F protein, called Pre-F-GCN4t, stabilized in a pre-F conformation. To show that Pre-F-GCN4t does not switch to a post-F conformation, it was compared with a recombinant post-F molecule, called Post-F-XC. Pre-F-GCN4t was glycosylated and trimeric and displayed a conformational stability different from that of Post-F-XC, as shown by chemical denaturation. Electron microscopy analysis suggested that Pre-F-GCN4t adopts a lollipop-like structure. In contrast, Post-F-XC had a typical elongated conical shape. Hydrogen/deuterium exchange mass spectrometry demonstrated that the two molecules had common rigid folding core and dynamic regions and provided structural insight for their biophysical and biochemical properties and reactivity. Pre-F-GCN4t was shown to deplete hRSV-neutralizing antibodies from human serum more efficiently than Post-F-XC. Importantly, Pre-F-GCN4t was also shown to bind D25, a highly potent monoclonal antibody specific for the pre-F conformation. In conclusion, this construct presents several pre-F characteristics, does not switch to the post-F conformation, and presents antigenic features required for a protective neutralizing antibody response. Therefore, Pre-F-GCN4t can be considered a promising candidate vaccine antigen.IMPORTANCE Human respiratory syncytial virus (RSV) is a global leading cause of infant mortality and adult morbidity. The development of a safe and efficacious RSV vaccine remains an important goal. The RSV class I fusion (F) glycoprotein is considered one of the most promising vaccine candidates, and recent evidences suggest that the prefusion (pre-F) state is a superior target for neutralizing antibodies. Our study presents the physicochemical characterization of Pre-F-GCN4t, a molecule designed to be stabilized in the pre-F conformation. To confirm its pre-F conformation, Pre-F-GCN4t was analyzed in parallel with Post-F-XC, a molecule in the post-F conformation. Our results show that Pre-F-GCN4t presents characteristics of a stabilized pre-F conformation and support its use as an RSV vaccine antigen. Such an antigen may represent a significant advance in the development of an RSV vaccine.