Determining the Seasonality of Respiratory Syncytial Virus in the United States: The Impact of Increased Molecular Testing

Pollen and viruses contribute to spatio-temporal variation in asthma-related emergency department visits

BACKGROUND

Asthma exacerbations are an important cause of emergency department visits but much remains unknown about the role of environmental triggers including viruses and allergenic pollen. A better understanding of spatio-temporal variation in exposure and risk posed by viruses and pollen types could help prioritize public health interventions.

OBJECTIVE

Here we quantify the effects of regionally important Cupressaceae pollen, tree pollen, other pollen types, rhinovirus, seasonal coronavirus, respiratory syncytial virus, and influenza on asthma-related emergency department visits for people living near eight pollen monitoring stations in Texas.

METHODS

We used age stratified Poisson regression analyses to quantify the effects of allergenic pollen and viruses on asthma-related emergency department visits.

RESULTS

Young children (<5 years of age) had high asthma-related emergency department rates (24.1 visits/1,000,000 person-days), which were mainly attributed to viruses (51.2%). School-aged children also had high rates (20.7 visits/1,000,000 person-days), which were attributed to viruses (57.0%), Cupressaceae pollen (0.7%), and tree pollen (2.8%). Adults had lower rates (8.1 visits/1,000,000 person-days) which were attributed to viruses (25.4%), Cupressaceae pollen (0.8%), and tree pollen (2.3%). This risk was spread unevenly across space and time; for example, during peak Cuppressaceae season, this pollen accounted for 8.2% of adult emergency department visits near Austin where these plants are abundant, but 0.4% in cities like Houston where they are not; results for other age groups were similar.

CONCLUSIONS

Although viruses are a major contributor to asthma-related emergency department visits, airborne pollen can explain a meaningful portion of visits during peak pollen season and this risk varies over both time and space because of differences in plant composition.

Respiratory Syncytial Virus: Epidemiology, Burden of Disease, and Clinical Update

Respiratory syncytial virus (RSV) is a common viral pathogen that accounts about 33 million cases of acute lower respiratory tract infection (LRTI) worldwide in children under the age of 5 years each year. High-risk populations, particularly preterm infants, those with underlying chronic lung disease, congenital heart disease, or compromised immune systems, are afflicted most significantly. RSV infection is characterized by significant amount of mucus and submucosal edema in the respiratory tract, leading to congestion and, oftentimes, significant respiratory distress. Antigen- and PCR-based testing are used to diagnose RSV infection.

Epidemiology and viral loads of respiratory syncytial virus in hospitalized children prior to and during COVID-19 pandemic in Hangzhou, China

Non-pharmaceutical interventions (NPIs) implemented to control SARS-CoV-2 have significantly influenced the activity of respiratory pathogens. This study investigated epidemiological changes among hospitalized patients with respiratory syncytial virus (RSV) before (2017-2019) and during (2020-2022) the COVID-19 pandemic in Hangzhou, China. We also examined viral load distribution across demographic and temporal variables. Nasopharyngeal swabs were collected and RSV loads were quantified using reverse transcriptase polymerase chain reaction (RT-qPCR). RSV epidemic characteristics, seasonal dynamics, and viral load distributions were compared between pre- and pandemic years. General linear models were employed to assess associations between viral loads and age. Among 19 742 cases, 1576 and 2092 tested positive during the pre- and pandemic years, respectively. From February to July 2020, the implementation of NPIs led to the cessation of RSV circulation. However, after these measures were relaxed, RSV cases resurged over two consecutive seasons during the pandemic, notably affecting older children compared to those in the pre-pandemic years (1.00 years, IQR: 0.50-2.00 vs. 0.58 years, IQR: 0.27-1.00, p < 0.001). Specifically, in 2021-2022, an off-season resurgence of RSV began earlier (mid-June), lasted longer (40 weeks), and involved more positive cases (1238 cases) than both 2020-2021 and pre-pandemic years. Viral load distribution demonstrated a clear age-related relationship in both pre- and pandemic years, with younger children consistently showing higher viral loads, independently of gender and season (all p-values for trends <0.001). These findings highlight the impact of NPIs on RSV epidemiology and underscore the need to prioritize RSV infection prevention in younger children from the perspective of viral load.

Saudi Initiative of Bronchiolitis Diagnosis, Management, and Prevention 2024 updated consensus on the prevention of respiratory syncytial virus

Respiratory syncytial virus (RSV) is the major cause of bronchiolitis among children under 5 years of age worldwide, accounting for a prevalence of 25%-88% in Saudi Arabia. Although no effective treatment for the virus exists, passive immunoprophylaxis reduced RSV hospitalizations in high-risk children. With recent advances in immunization, the Saudi Initiative of Bronchiolitis Diagnosis, Management, and Prevention panel screened recent relevant international guidelines, locally published data, and expert consensus to update guidelines for RSV prevention, taking into consideration the resources, timing, varying health profiles, and RSV burden in Saudi Arabia. The panel updated its recommendations to include immunization of infants, mothers, and older adults. Practical guidelines were prepared to facilitate the administration of the short-acting and newly developed long-acting RSV monoclonal antibodies (mAb) during the regular follow-ups of high-risk infants in specialized clinics. In addition, long-acting mAb was highlighted as all-infant protection in the routine immunization calendar.

Respiratory Syncytial Virus-Associated Hospitalizations in Children <5 Years: 2016-2022

BACKGROUND

The coronavirus disease 2019 pandemic disrupted respiratory syncytial virus (RSV) seasonality resulting in early, atypical RSV seasons in 2021 and 2022, with an intense 2022 peak overwhelming many pediatric healthcare facilities.

METHODS

We conducted prospective surveillance for acute respiratory illness during 2016-2022 at 7 pediatric hospitals. We interviewed parents, reviewed medical records, and tested respiratory specimens for RSV and other respiratory viruses. We estimated annual RSV-associated hospitalization rates in children aged <5 years and compared hospitalization rates and characteristics of RSV-positive hospitalized children over 4 prepandemic seasons (2016-2020) to those hospitalized in 2021 or 2022.

RESULTS

There was no difference in median age or age distribution between prepandemic and 2021 seasons. Median age of children hospitalized with RSV was higher in 2022 (9.6 months vs 6.0 months, P < .001). RSV-associated hospitalization rates were higher in 2021 and 2022 than the prepandemic average across age groups. Comparing 2021 to 2022, RSV-associated hospitalization rates were similar among children <2 years of age; however, children aged 24 to 59 months had significantly higher rates of RSV-associated hospitalization in 2022 (rate ratio 1.68 [95% confidence interval 1.37-2.00]). More RSV-positive hospitalized children received supplemental oxygen and there were more respiratory virus codetections in 2022 than in prepandemic seasons (P < .001 and P = .003, respectively), but there was no difference in the proportion hypoxemic, mechanically ventilated, or admitted to intensive care.

CONCLUSIONS

The atypical 2021 and 2022 RSV seasons resulted in higher hospitalization rates with similar disease severity to prepandemic seasons.

Risk Analysis of Respiratory Syncytial Virus Among Infants in the United States by Birth Month

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality among US infants. A child's calendar birth month determines their age at first exposure(s) to RSV. We estimated birth month-specific risk of medically attended (MA) RSV lower respiratory tract infection (LRTI) among infants during their first RSV season and first year of life (FYOL).

METHODS

We analyzed infants born in the USA between July 2016 and February 2020 using three insurance claims databases (two commercial, one Medicaid). We classified infants' first MA RSV LRTI episode by the highest level of care incurred (outpatient, emergency department, or inpatient), employing specific and sensitive diagnostic coding algorithms to define index RSV diagnoses. In our main analysis, we focused on infants' first RSV season. In our secondary analysis, we compared the risk of MA RSV LRTI during infants' first RSV season to that of their FYOL.

RESULTS

Infants born from May through September generally had the highest risk of first-season MA RSV LRTI-approximately 6-10% under the specific RSV index diagnosis definition and 16-26% under the sensitive. Infants born between October and December had the highest risk of RSV-related hospitalization during their first season. The proportion of MA RSV LRTI events classified as inpatient ranged from 9% to 54% (specific) and 5% to 33% (sensitive) across birth month and comorbidity group. Through the FYOL, the overall risk of MA RSV LRTI is comparable across birth months within each claims database (6-11% under the specific definition, 17-30% under the sensitive), with additional cases progressing to care at outpatient or ED settings.

CONCLUSIONS

Our data support recent national recommendations for the use of nirsevimab in the USA. For infants born at the tail end of an RSV season who do not receive nirsevimab, a dose administered prior to the onset of their second RSV season could reduce the incidence of outpatient- and ED-related events.

Acute Respiratory Tract Infections (ARTIs) in Children after COVID-19-Related Social Distancing: An Epidemiological Study in a Single Center of Southern Italy

In Sicily (Italy), respiratory syncytial virus (RSV), rhinovirus (HRV), and influenza virus triggered epidemics among children, resulting in an increase in acute respiratory tract infections (ARTIs). Our objective was to capture the epidemiology of respiratory infections in children, determining which pathogens were associated with respiratory infections following the lockdown and whether there were changes in the epidemiological landscape during the post-SARS-CoV-2 pandemic era.

MATERIALS AND METHODS

We analyzed multiplex respiratory viral PCR data (BioFire® FilmArray® Respiratory Panel 2.1 Plus) from 204 children presenting with respiratory symptoms and/or fever to our Unit of Pediatrics and Pediatric Emergency.

RESULTS

Viruses were predominantly responsible for ARTIs (99%), with RSV emerging as the most common agent involved in respiratory infections, followed by human rhinovirus/enterovirus and influenza A. RSV and rhinovirus were also the primary agents in coinfections. RSV predominated during winter months, while HRV/EV exhibited greater prevalence than RSV during the fall. Some viruses spread exclusively in coinfections (human coronavirus NL63, adenovirus, metapneumovirus, and parainfluenza viruses 1-3), while others primarily caused mono-infections (influenza A and B). SARS-CoV-2 was detected equally in both mono-infections (41%) and coinfections (59%).

CONCLUSIONS

Our analysis underlines the predominance of RSV and the importance of implementing preventive strategies for RSV.

Global Seasonal Activities of Respiratory Syncytial Virus Before the Coronavirus Disease 2019 Pandemic: A Systematic Review

Varied seasonal patterns of respiratory syncytial virus (RSV) have been reported worldwide. We conducted a systematic review on articles identified in PubMed reporting RSV seasonality based on data collected before 1 January 2020. RSV seasonal patterns were examined by geographic location, calendar month, analytic method, and meteorological factors including temperature and absolute humidity. Correlation and regression analyses were conducted to explore the relationship between RSV seasonality and study methods and characteristics of study locations. RSV seasons were reported in 209 articles published in 1973-2023 for 317 locations in 77 countries. Regular RSV seasons were similarly reported in countries in temperate regions, with highly variable seasons identified in subtropical and tropical countries. Longer durations of RSV seasons were associated with a higher daily average mean temperature and daily average mean absolute humidity. The global seasonal patterns of RSV provided important information for optimizing interventions against RSV infection.

Observations of Respiratory Syncytial Virus (RSV) Nucleic Acids in Wastewater Solids Across the United States in the 2022-2023 Season: Relationships with RSV Infection Positivity and Hospitalization Rates

Respiratory syncytial virus (RSV) is a leading cause of respiratory illness and hospitalization, but clinical surveillance detects only a minority of cases. Wastewater surveillance could determine the onset and extent of RSV circulation in the absence of sensitive case detection, but to date, studies of RSV in wastewater are few. We measured RSV RNA concentrations in wastewater solids from 176 sites during the 2022-2023 RSV season and compared those to publicly available RSV infection positivity and hospitalization rates. Concentrations ranged from undetectable to 107 copies per gram. RSV RNA concentration aggregated at state and national levels correlated with infection positivity and hospitalization rates. RSV season onset was determined using both wastewater and clinical positivity rates using independent algorithms for 14 states where both data were available at the start of the RSV season. In 4 of 14 states, wastewater and clinical surveillance identified RSV season onset during the same week; in 3 states, wastewater onset preceded clinical onset, and in 7 states, wastewater onset occurred after clinical onset. Wastewater concentrations generally peaked in the same week as hospitalization rates but after case positivity rates peaked. Differences in onset and peaks in wastewater versus clinical data may reflect inherent differences in the surveillance approaches.

Seasonality of respiratory syncytial virus infection in children hospitalized with acute lower respiratory tract infections in Hunan, China, 2013-2022

BACKGROUND

In China, respiratory syncytial virus (RSV) infections traditionally occur during the spring and winter seasons. However, a shift in the seasonal trend was noted in 2020-2022, during the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

This study investigated the seasonal characteristics of RSV infection in children hospitalized with acute lower respiratory tract infections (ALRTIs). The RSV epidemic season was defined as RSV positivity in > 10% of the hospitalized ALRTI cases each week. Nine RSV seasons were identified between 2013 and 2022, and nonlinear ordinary least squares regression models were used to assess the differences in year-to-year epidemic seasonality trends.

RESULTS

We enrolled 49,658 hospitalized children diagnosed with ALRTIs over a 9-year period, and the RSV antigen-positive rate was 15.2% (n = 7,566/49,658). Between 2013 and 2022, the average onset and end of the RSV season occurred in week 44 (late October) and week 17 of the following year, respectively, with a typical duration of 27 weeks. However, at the onset of the COVID-19 pandemic, the usual spring RSV peak did not occur. Instead, the 2020 epidemic started in week 32, and RSV seasonality persisted into 2021, lasting for an unprecedented 87 weeks before concluding in March 2022.

CONCLUSIONS

RSV seasonality was disrupted during the COVID-19 pandemic, and the season exhibited an unusually prolonged duration. These findings may provide valuable insights for clinical practice and public health considerations.

Determining the timing of respiratory syncytial virus (RSV) epidemics: a systematic review, 2016 to 2021; method categorisation and identification of influencing factors

BackgroundThere is currently no standardised approach to estimate respiratory syncytial virus (RSV) epidemics' timing (or seasonality), a critical information for their effective prevention and control.AimWe aimed to provide an overview of methods to define RSV seasonality and identify factors supporting method choice or interpretation/comparison of seasonal estimates.MethodsWe systematically searched PubMed and Embase (2016-2021) for studies using quantitative approaches to determine the start and end of RSV epidemics. Studies' features (data-collection purpose, location, regional/(sub)national scope), methods, and assessment characteristics (case definitions, sampled population's age, in/outpatient status, setting, diagnostics) were extracted. Methods were categorised by their need of a denominator (i.e. numbers of specimens tested) and their retrospective vs real-time application. Factors worth considering when choosing methods and assessing seasonal estimates were sought by analysing studies.ResultsWe included 32 articles presenting 49 seasonality estimates (18 thereof through the 10% positivity threshold method). Methods were classified into eight categories, two requiring a denominator (1 retrospective; 1 real-time) and six not (3 retrospective; 3 real-time). A wide range of assessment characteristics was observed. Several studies showed that seasonality estimates varied when methods differed, or data with dissimilar assessment characteristics were employed. Five factors (comprising study purpose, application time, assessment characteristics, healthcare system and policies, and context) were identified that could support method choice and result interpretation.ConclusionMethods and assessment characteristics used to define RSV seasonality are heterogeneous. Our categorisation of methods and proposed framework of factors may assist in choosing RSV seasonality methods and interpretating results.

A cost-consequence analysis of the Xpert Xpress CoV-2/Flu/RSV plus test strategy for the diagnosis of influenza-like illnesses

AIMS

Influenza-like illnesses (ILI) affect millions each year in the United States (US). Determining definitively the cause of symptoms is important for patient management. Xpert Xpress CoV-2/Flu/RSV plus (Xpert Xpress) is a rapid, point-of-care (POC), multiplex real-time polymerase chain reaction (RT-PCR) test intended for the simultaneous qualitative detection and differentiation of SARS-CoV-2, influenza A/B, and respiratory syncytial virus (RSV). The objective of our analysis was to develop a cost-consequence model (CCM) demonstrating the clinico-economic impacts of implementing PCR testing with Xpert Xpress compared to current testing strategies.

METHODS

A decision tree model, with a 1-year time horizon, was used to compare testing with Xpert Xpress alone to antigen POC testing and send-out PCR strategies in the US outpatient setting from a payer perspective. A hypothetical cohort of 1,000,000 members was modeled, a portion of whom develop symptomatic ILIs and present to an outpatient care facility. Our main outcome measure is cost per correct treatment course.

RESULTS

The total cost per correct treatment course was $1,131 for the Xpert Xpress strategy compared with a range of $3,560 to $5,449 in comparators. POC antigen testing strategies cost more, on average, than PCR strategies.

LIMITATIONS

Simplifying model assumptions were used to allow for modeling ease. In clinical practice, treatment options, costs, and diagnostic test sensitivity and specificity may differ from what is included in the model. Additionally, the most recent incidence and prevalence data was used within the model, which is not reflective of historical averages due to the SARS-CoV-2 pandemic.

CONCLUSION

The Xpert Xpress CoV-2/Flu/RSV plus test allows for rapid and accurate diagnostic results, leading to reductions in testing costs and downstream healthcare resource utilization compared to other testing strategies. Compared to POC antigen testing strategies, PCR strategies were more efficient due to improved diagnostic accuracy and reduced use of confirmatory testing.

Characteristics of respiratory viruses' circulation through a six-year period (2016-2022) in a pediatric population in Normandy, France, and the impact of COVID-19 pandemic

IMPORTANCE

The report highlights an epidemiological change in the circulation of respiratory viruses in pediatric populations due to strategies adopted against COVID-19 pandemic. COVID-19 has resulted in a significant increase in requests for multiplex respiratory research to identify the virus responsible for the symptoms. The diagnostic needs have increased, and the number of samples analyzed in 2021-2022 is equal to the samples analyzed over the four epidemic periods preceding the pandemic. The report suggests the importance of active surveillance of respiratory viruses' circulation and new recommendations for respiratory virus detection in pediatric patients.

Epidemiology of RSV Bronchiolitis Among Young Children in Central New York Before and After the Onset of the COVID-19 Pandemic

BACKGROUND

Respiratory syncytial virus (RSV) bronchiolitis is the leading cause of hospitalizations among infants in the United States. Unpredictability in RSV seasonality has occurred following the onset of the coronavirus disease 2019 (COVID-19) pandemic. Local surveillance networks can enhance the ability to appropriately time prophylaxis when exposure risk is highest.

METHODS

A retrospective, cohort study was conducted to describe the epidemiologic patterns of RSV disease among outpatient, emergency department and inpatient encounters in children <5 years in Central New York before and after the onset of the COVID-19 pandemic. Local data were collected from October 2015 to January 2023 and compared to state-level data. Linear regression models were used to identify clinical and sociodemographic differences before and after the pandemic.

RESULTS

Local variation in RSV seasonality was noted prior to the COVID-19 pandemic, however highly atypical circulation patterns appeared in the post-COVID-19 era. Since March 2020, patterns for local and state-defined RSV seasons have remained atypical (local season onset in 2021: week 27 and 2022: week 27; state season onset in 2021: week 31 and 2022: week 38). After adjusting for increases in testing, RSV bronchiolitis cases were not significantly different during pre- and post-pandemic eras. In comparison to the 2021 bronchiolitis season, the 2022 season had a higher proportion of RSV cases despite decreased testing.

CONCLUSIONS

Temporal patterns for RSV have shifted during the COVID-19 pandemic. Local surveillance networks may be advantageous in trending community-level RSV activity to optimize prophylaxis administration. Changes in RSV testing patterns occurred throughout the study period and should be accounted for when describing infant and childhood RSV disease.

Wastewater-based epidemiology revealed in advance the increase of enterovirus circulation during the Covid-19 pandemic

Wastewater-based epidemiology (WBE) was conducted to track Enteroviruses (EVs) circulation in the Milan metropolitan area (Northern Italy) during Covid-19 pandemic (March 2020-December 2022). 202 composite 24-hour wastewater samples (WWSs) were collected weekly from March 24, 2020, to December 29, 2022 at the inlet of two wastewater treatment plants (WWTP) in Milan (1.5 million inhabitants). EV-RNA was quantified and molecular characterization of non-polio EVs (NPEV) was performed by Sanger sequence analysis. Data from WWS were matched with virological data collected in the framework of Influenza-Like Illness (ILI) surveillance in the same place and time. EV-RNA was identified in 88.2 % of WWSs. The peak in EVs circulation was observed in late August 2020 (upon conclusion of the first national lockdown), in late August 2021, and in mid-April 2022. EV-RNA concentration in WWS (normalized as copies/d/1000 people) at peak of circulation presented a yearly increase (2020: 2.47 × 1010; 2021: 6.81 × 1010; 2022: 2.14 × 1011). This trend overlapped with trend in EV-positivity rate in ILI cases, expanded from 21.7 % in 2021 to 55.6 % in 2022. EV trends in WWS preceded clinical sample detections in 2021 and 2022 by eight and five weeks, respectively, acting as an early warning of outbreak. Although sequencing of EV-positive WWSs revealed the presence of multiple EV strains, typing remained inconclusive. Molecular characterization of EVs in clinical samples revealed the co-circulation of several genotypes: EV-A accounted for 60 % of EVs, EV-B for 16.7 %, EV-D68 for 23.3 %. EVs were circulating in Milan metropolitan area between March 2020 and December 2022. The epidemiological trends unfolded the progressive accumulation of EV transmission in the population after removal of Covid-19 restrictions. The increased circulation of EVs in 2021-2022 was identified at least 35 days in advance compared to the analysis of clinical data. The inconclusive results of Sanger sequencing lookout for improvement and innovative molecular approaches to deepen track EVs.

Repeatability and timing of tropical influenza epidemics

Much of the world experiences influenza in yearly recurring seasons, particularly in temperate areas. These patterns can be considered repeatable if they occur predictably and consistently at the same time of year. In tropical areas, including southeast Asia, timing of influenza epidemics is less consistent, leading to a lack of consensus regarding whether influenza is repeatable. This study aimed to assess repeatability of influenza in Vietnam, with repeatability defined as seasonality that occurs at a consistent time of year with low variation. We developed a mathematical model incorporating parameters to represent periods of increased transmission and then fitted the model to data collected from sentinel hospitals throughout Vietnam as well as four temperate locations. We fitted the model for individual (sub)types of influenza as well as all combined influenza throughout northern, central, and southern Vietnam. Repeatability was evaluated through the variance of the timings of peak transmission. Model fits from Vietnam show high variance (sd = 64-179 days) in peak transmission timing, with peaks occurring at irregular intervals and throughout different times of year. Fits from temperate locations showed regular, annual epidemics in winter months, with low variance in peak timings (sd = 32-57 days). This suggests that influenza patterns are not repeatable or seasonal in Vietnam. Influenza prevention in Vietnam therefore cannot rely on anticipation of regularly occurring outbreaks.

Contribution of the FilmArray BioFire® Technology in the Diagnosis of Viral Respiratory Infections during the COVID-19 Pandemic at Ibn Sina University Hospital Center in Rabat: Epidemiological Study about 503 Cases

Respiratory viruses are the most involved pathogens in acute respiratory infections. During the COVID-19 pandemic, new elements have been brought to this topic, especially at the diagnostic and therapeutic level. The objective of this work is to describe the epidemiology of respiratory viruses in patients admitted to the Ibn Sina University Hospital of Rabat during a period characterized by the emergence and spread of SARS-CoV-2. We conducted a retrospective study from January 1 to December 31. We included all patients treated for acute respiratory infection and for whom a multiplex respiratory panel PCR was requested. Virus detection was performed using a FilmArray RP 2.1 plus BioFire multiplex respiratory panel. The study population was relatively adults with a mean age of 39 years. The sex ratio M/F was 1.20. The survey revealed a high prevalence of 42.3% of patients hospitalized in the adult intensive care unit whose respiratory distress was the most common reason for hospitalization (58%). The positivity rate was 48.1%. This rate was higher in the pediatric population 83.13% compared to adults 29.7%. Monoinfection was found in 36.4% of cases, and codetection in 11.7% of cases. This survey revealed that a total of 322 viruses were detected, HRV being the most incriminated virus (48.7%), followed by RSV in 13.8% of patients. Considering the five most detected viruses in our study (HRV, RSV, PIV3, ADV, and hMPV), we found that the incidence was significantly higher in the pediatric population. SARS-CoV-2 was detected only in adult's population. In our study, we found that influenza A and B viruses, PIV2, MERS, and all bacteria were not detected by this kit during the study period. Regarding the seasonal distribution, RSV and hMPV showed a significantly high incidence during autumn and summer and SARS-CoV-2 and CoV OC43 showed a high peak during winter. In this study, we found a lack of detection of influenza virus and a shift in the usual winter peak of RSV to the summer, while the detection of ADV and HRV was less affected. This difference in detection could be due on the one hand to the difference in stability between enveloped and nonenveloped viruses and on the other hand to the escape of certain viruses to the different sanitary measures introduced after the declaration of the COVID-19 pandemic. These same measures were effective against enveloped viruses such as RSV and influenza viruses. The emergence of SARS-CoV-2 has modified the epidemiology of other respiratory viruses, either directly by viral interference or indirectly by the preventive measures taken.

Resurgence of Respiratory Syncytial Virus in Children: An Out-of-Season Epidemic in Portugal

INTRODUCTION

An out-of-season increase in respiratory syncytial virus (RSV) incidence was observed in Portugal from June 2021 onwards, revealing a continuing surge in cases throughout 2021/2022 autumn/winter. We aimed to describe this out-of-season epidemic and define its epidemic period, by analysing RSV incidence from week 40 of 2020 (2020-W40) to week 18 of 2022 (2022-W18).

MATERIAL AND METHODS

Surveillance data on weekly RSV laboratory confirmed cases, in Portugal, was used to monitor RSV incidence using CUSUM test methodology for count data.

RESULTS

In 2021-W23, the CUSUM score identified a significant increase in the risk of RSV. By that time, the percentage of RSV positive tests rose from 1% in 2021-W22 (3/265) to 6% in 2021-W23 (18/298). Despite a sharp decrease in RSV incidence on 2021-W33 and on 2022-W02, the CUSUM score stayed over the limit up to 2022-W07, indicating that the RSV activity remained at an epidemic level. Distinct peaks of RSV cases were observed between 2021-W30 and 2021-W32 (average of 77 RSV cases per week) and between 2021-W39 and 2021-W41 (average of 79 RSV cases per week) with positivity rates around 60%.

CONCLUSION

An out-of-season RSV epidemic was identified, with a longer epidemic period compared with previous seasons. Possible reasons include relaxation of COVID-19 physical distancing measures and a greater proportion of population susceptible to disease. As several factors may change the pattern of RSV activity, countries should implement year-round surveillance RSV surveillance systems. These findings might have an impact on public health planning regarding future RSV surges, namely, on the palivizumab prophylaxis period for high-risk infants.

Seasonality of Respiratory Syncytial Virus - United States, 2017-2023

In the United States, respiratory syncytial virus (RSV) infections cause an estimated 58,000-80,000 hospitalizations among children aged <5 years (1,2) and 60,000-160,000 hospitalizations among adults aged ≥65 years each year (3-5). U.S. RSV epidemics typically follow seasonal patterns, peaking in December or January (6,7), but the COVID-19 pandemic disrupted RSV seasonality during 2020-2022 (8). To describe U.S. RSV seasonality during prepandemic and pandemic periods, polymerase chain reaction (PCR) test results reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS)* during July 2017-February 2023 were analyzed. Seasonal RSV epidemics were defined as the weeks during which the percentage of PCR test results that were positive for RSV was ≥3% (9). Nationally, prepandemic seasons (2017-2020) began in October, peaked in December, and ended in April. During 2020-21, the typical winter RSV epidemic did not occur. The 2021-22 season began in May, peaked in July, and ended in January. The 2022-23 season started (June) and peaked (November) later than the 2021-22 season, but earlier than prepandemic seasons. In both prepandemic and pandemic periods, epidemics began earlier in Florida and the Southeast and later in regions further north and west. With several RSV prevention products in development,^† ongoing monitoring of RSV circulation can guide the timing of RSV immunoprophylaxis and of clinical trials and postlicensure effectiveness studies. Although the timing of the 2022-23 season suggests that seasonal patterns are returning toward those observed in prepandemic years, clinicians should be aware that off-season RSV circulation might continue.

Summarizing Study Characteristics and Diagnostic Performance of Commercially Available Tests for Respiratory Syncytial Virus: A Scoping Literature Review in the COVID-19 Era

BACKGROUND

Nonpharmaceutical interventions to prevent the spread of coronavirus disease 2019 also decreased the spread of respiratory syncytial virus (RSV) and influenza. Viral diagnostic testing in patients with respiratory tract infections (RTI) is a necessary tool for patient management; therefore, sensitive and specific tests are required. This scoping literature review aimed to summarize the study characteristics of commercially available sample-to-answer RSV tests.

CONTENT

PubMed and Embase were queried for studies reporting on the diagnostic performance of tests for RSV in patients with RTI (published January 2005-January 2021). Information on study design, patient and setting characteristics, and published diagnostic performance of RSV tests were extracted from 77 studies that met predefined inclusion criteria. A literature gap was identified for studies of RSV tests conducted in adult-only populations (5.3% of total subrecords) and in outpatient (7.5%) or household (0.8%) settings. Overall, RSV tests with analytical time >30 min had higher published sensitivity (62.5%-100%) vs RSV tests with analytical time ≤30 min (25.7%-100%); this sensitivity range could be partially attributed to the different modalities (antigen vs molecular) used. Molecular-based rapid RSV tests had higher published sensitivity (66.7%-100%) and specificity (94.3%-100%) than antigen-based RSV tests (sensitivity: 25.7%-100%; specificity:80.3%-100%).

SUMMARY

This scoping review reveals a paucity of literature on studies of RSV tests in specific populations and settings, highlighting the need for further assessments. Considering the implications of these results in the current pandemic landscape, the authors preliminarily suggest adopting molecular-based RSV tests for first-line use in these settings.

On the lookout for influenza viruses in Italy during the 2021-2022 season: Along came A(H3N2) viruses with a new phylogenetic makeup of their hemagglutinin

AIMS

To assess influenza viruses (IVs) circulation and to evaluate A(H3N2) molecular evolution during the 2021-2022 season in Italy.

MATERIALS AND METHODS

12,393 respiratory specimens (nasopharyngeal swabs or broncho-alveolar lavages) collected from in/outpatients with influenza illness in the period spanning from January 1, 2022 (week 2022-01) to May 31, 2022 (week 2022-22) were analysed to identify IV genome and were molecularly characterized by 12 laboratories throughout Italy. A(H3N2) evolution was studied by conducting an in-depth phylogenetic analysis of the hemagglutinin (HA) gene sequences. The predicted vaccine efficacy (pVE) of vaccine strain against circulating A(H3N2) viruses was estimated using the sequence-based P_epitope model.

RESULTS

The overall IV-positive rate was 7.2% (894/12,393), all were type A IVs. Almost all influenza A viruses (846/894; 94.6%) were H3N2 that circulated in Italy with a clear epidemic trend, with 10% positivity rate threshold crossed for six consecutive weeks from week 2022-11 to week 2022-16. According to the phylogenetic analysis of a subset of A(H3N2) strains (n=161), the study HA sequences were distributed into five different genetic clusters, all of them belonging to the clade 3C.2a, sub-clade 3C.2a1 and the genetic subgroup 3C.2a1b.2a.2. The selective pressure analysis of A(H3N2) sequences showed evidence of diversifying selection particularly in the amino acid position 156. The comparison between the predicted amino acid sequence of the 2021-2022 vaccine strain (A/Cambodia/e0826360/2020) and the study strains revealed 65 mutations in 59 HA amino acid positions, including the substitution H156S and Y159N in antigenic site B, within major antigenic sites adjacent to the receptor-binding site, suggesting the presence of drifted strains. According to the sequence-based P_epitope model, antigenic site B was the dominant antigenic site and the p(VE) against circulating A(H3N2) viruses was estimated to be -28.9%.

DISCUSSION AND CONCLUSION

After a long period of very low IV activity since public health control measures have been introduced to face COVID-19 pandemic, along came A(H3N2) with a new phylogenetic makeup. Although the delayed 2021-2022 influenza season in Italy was characterized by a significant reduction of the width of the epidemic curve and in the intensity of the influenza activity compared to historical data, a marked genetic diversity of the HA of circulating A(H3N2) strains was observed. The identification of the H156S and Y159N substitutions within the main antigenic sites of most HA sequences also suggested the circulation of drifted variants with respect to the 2021-2022 vaccine strain. Molecular surveillance plays a critical role in the influenza surveillance architecture and it has to be strengthened also at local level to timely assess vaccine effectiveness and detect novel strains with potential impact on public health.

Clinical features and viral etiology of acute respiratory infection in an outpatient fever clinic during COVID-19 pandemic in a tertiary hospital in Nanjing, China

BACKGROUND

Clinical feature and viral etiology for acute respiratory infection (ARI) in the community was unknown during coronavirus disease 2019 (COVID-19) pandemic.

OBJECTIVE

In a retrospective study, we aimed to characterize the clinical feature and etiology for the ARI patients admitted to the outpatient fever clinic in Nanjing Drum Tower Hospital between November 2020 and March 2021.

METHODS

Fifteen common respiratory pathogens were tested using pharyngeal swabs by multiplex reverse transcriptase-polymerase chain reaction assays.

RESULTS

Of the 242 patients, 56 (23%) were tested positive for at least one viral agent. The predominant viruses included human rhinovirus (HRV) (5.4%), parainfluenza virus type III (PIV-III) (5.0%), and human coronavirus-NL63 (HCoV-NL63) (3.7%). Cough, sputum, nasal obstruction, and rhinorrhea were the most prevalent symptoms in patients with viral infection. Elderly and the patients with underlying diseases were susceptible to pneumonia accompanied with sputum and chest oppression. Three (5.4%) patients in virus infection group, whereas 31 (16.7%) in non-viral infection group (p = 0.033), were empirically prescribed with antiviral agents. Among 149 patients who received antibiotic therapy, 30 (20.1%) patients were later identified with viral infection.

CONCLUSION

Our study indicated the importance of accurate diagnosis of ARI, especially during the COVID-19 pandemic, which might facilitate appropriate clinical treatment.

Seasonality of Common Human Coronaviruses, United States, 2014-20211

The 4 common types of human coronaviruses (HCoVs)-2 alpha (HCoV-NL63 and HCoV-229E) and 2 beta (HCoV-HKU1 and HCoV-OC43)-generally cause mild upper respiratory illness. Seasonal patterns and annual variation in predominant types of HCoVs are known, but parameters of expected seasonality have not been defined. We defined seasonality of HCoVs during July 2014-November 2021 in the United States by using a retrospective method applied to National Respiratory and Enteric Virus Surveillance System data. In the 6 HCoV seasons before 2020-21, season onsets occurred October 21-November 12, peaks January 6-February 13, and offsets April 18-June 27; most (>93%) HCoV detection was within the defined seasonal onsets and offsets. The 2020-21 HCoV season onset was 11 weeks later than in prior seasons, probably associated with COVID-19 mitigation efforts. Better definitions of HCoV seasonality can be used for clinical preparedness and for determining expected patterns of emerging coronaviruses.

The role of birth month in the burden of hospitalisations for acute lower respiratory infections due to respiratory syncytial virus in young children in Croatia

Background

Birth month was an important risk factor for respiratory syncytial virus (RSV) hospitalisation in infants. However, little is known about the role of birth month in RSV hospitalisation in finer age bands during infancy, which is relevant to strategies for RSV passive immunisations for infants. We aimed to understand the role of birth month in the burden of RSV-associated acute lower respiratory infection (ALRI) hospitalisation in finer age bands of the first year of life.

Methods

In this retrospective study, we analysed the hospitalisation records during 2014–19 at the University Hospital of Split, Split-Dalmatia County, Croatia. We estimated all-cause and RSV associated ALRI hospitalisation rates among children under five years, with a focus on infants by finer age band and birth month.

Results

We included 1897 ALRI hospitalisations during the study period. Overall in children under five years, annual hospitalisation rate was 14.66/1000 (95% CI: 14.01–15.34) for all-cause ALRI, and was 7.56/1000 (95% CI: 6.83–8.34) for RSV-ALRI. RSV-ALRI hospitalisation rate was highest in infants aged 28 days–<3 months (61.15/1000, 95% CI: 52.91–70.31). Infants born in November, December and January (2–3 months before RSV peak) had the highest hospitalisation rates during infancy. Depending on the birth month of infants, the risk of RSV-ALRI hospitalisation peaked at different months of age; infants who were born in September had the highest RSV-ALRI hospitalisation rate at the age of 3–<6 months.

Conclusions

Our study underlines the importance of birth month in planning RSV immunisation strategies for infants, and provides useful baseline data for effectiveness analysis of novel RSV prophylactic products.

Respiratory virus testing and clinical outcomes among children hospitalized with pneumonia

BACKGROUND

Despite the increased availability of diagnostic tests for respiratory viruses, their clinical utility for children with community-acquired pneumonia (CAP) remains uncertain.

OBJECTIVE

To identify patterns of respiratory virus testing across children's hospitals prior to the COVID-19 pandemic and to determine whether hospital-level rates of viral testing were associated with clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter retrospective cohort study of children hospitalized for CAP at 19 children's hospitals in the United States from 2010-2019.

MAIN OUTCOMES AND MEASURES

Using a novel method to identify the performance of viral testing, we assessed time trends in the use of viral tests, both overall and stratified by testing method. Adjusted proportions of encounters with viral testing were compared across hospitals and were correlated with length of stay, antibiotic and oseltamivir use, and performance of ancillary laboratory testing.

RESULTS

There were 46,038 hospitalizations for non-severe CAP among children without complex chronic conditions. The proportion with viral testing increased from 38.8% to 44.2% during the study period (p < .001). Molecular testing increased (27.2% to 40.0%, p < .001) and antigen testing decreased (33.2% to 7.8%, p < .001). Hospital-specific adjusted proportions of testing ranged from 10.0% to 83.5% and were not associated with length of stay, antibiotic use, or antiviral use. Hospitals that performed more viral testing did not have lower rates of ancillary laboratory testing.

CONCLUSIONS

Viral testing practices varied widely across children's hospitals and were not associated with clinically important process or outcome measures. Viral testing may not influence clinical management for many children hospitalized with CAP.

Microarray-Based Analyses of Rhinovirus Species-Specific Antibody Responses in Exacerbated Pediatric Asthma in a German Pediatric Cohort

Rhinoviruses (RV) account for a significant number of asthma exacerbations, and RV species C may be associated with a severe course in vulnerable patient groups. Despite important evidence on the role of RV reported by clinicians and life scientists, there are still unanswered questions regarding their influence on asthma exacerbation in young patients. Thus, we measured the RVspecies-specific IgG titers in our German pediatric exacerbation cohort using a microarray-based technology. For this approach, human sera of patients with exacerbated asthma and wheeze, as well as healthy control subjects (n = 136) were included, and correlation analyses were performed. Concordantly with previously published results, we observed significantly higher cumulative levels of RV species A-specific IgG (p = 0.011) and RV-C-specific IgG (p = 0.051) in exacerbated asthma group compared to age-matched controls. Moreover, atopic wheezers had increased RV-specific IgG levels for species A (p = 0.0011) and species C (p = 0.0009) compared to non-atopic wheezers. Hypothesizing that bacterial infection positively correlates with immune memory against RV, we included nasopharyngeal swab results in our analyses and detected limited correlations. Interestingly, the eosinophil blood titer positively correlated with RV-specific IgG levels. With these observations, we add important observations to the existing data regarding exacerbation in pediatric and adolescent medicine. We propose that scientists and clinicians should pay more attention to the relevance of RV species in susceptible pediatric patients.

RSV testing practice and positivity by patient demographics in the United States: integrated analyses of MarketScan and NREVSS databases

Background

RSV-incidence estimates obtained from routinely-collected healthcare data (e.g., MarketScan) are commonly adjusted for under-reporting using test positivity reported in national Surveillance Systems (NREVSS). However, NREVSS lacks detail on patient-level characteristics and the validity of applying a single positivity estimate across diverse patient groups is uncertain. We aimed to describe testing practices and test positivity across subgroups of private health insurance enrollees in the US and illustrate the possible magnitude of misclassification when using NREVSS to correct for RSV under ascertainment.

Methods

Using billing records, we determined distributions of RSV-test claims and test positivity among a national sample of private insurance enrollees. Tests were considered positive if they coincided with an RSV-diagnosis. We illustrated the influence of positivity variation across sub-populations when accounting for untested acute respiratory infections.

Results

Most tests were for children (age 0–4: 65.8%) and outpatient encounters (78.3%). Test positivity varied across age (0–4: 19.8%, 5–17: 1.8%, adults: 0.7%), regions (7.6–16.1%), settings (inpatient 4.7%, outpatient 14.2%), and test indication (5.0–35.9%). When compared to age, setting or indication-specific positivity, bias due to using NREVSS positivity to correct for untested ARIs ranged from − 76% to 3556%.

Conclusions

RSV-test positivity depends on the characteristics of patients for whom those tests were ordered. NREVSS-based correction for RSV-under-ascertainment underestimates the true incidence among children and overestimate rates among adults. Demographic-specific detail on testing practice and positivity can improve the accuracy of RSV-incidence estimates.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07659-x.

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.

Epidemiological and Clinical Characteristics of Respiratory Syncytial Virus Infections in Children Aged <5 Years in China, from 2014−2018

Respiratory syncytial virus (RSV) is an important pathogen that causes acute respiratory tract infections in children. To understand the epidemiological and clinical characteristics of RSV in children, we analyzed the RSV diagnostic testing results from the 2014−2018 surveillance of acute respiratory infections in China. Among children aged <5 years, RSV incidence during 2014−2018 was 17.3% (3449/19,898), and 89.1% of RSV-positive individuals were inpatients. Children aged < 6 months had a high proportion in RSV infected individual (n = 1234; 35.8%). The highest RSV detection rate was in winter, RSV-A and RSV-B co-circulated year-round and jointly prevailed in 2015−2016. Cough was the common symptom of RSV infection 93.2% (3216/3449). Compared with older children, those aged <6 months were more likely to show breathing difficulty or lung rale that further developed into bronchopneumonia (p < 0.001). The symptoms such as cough, running nose, and diarrhea had significant differences between the RSV-A and RSV-B groups. The rate of RSV co-detection with other viruses or bacteria was 35.4%. Those coinfected with other viruses had a significantly higher incidence of fever, whereas those coinfected with bacteria had higher incidences of breathing difficulty and severe pneumonia. Our findings highlight the need for accumulating epidemiological information for the prevention and control of RSV.

Predictors of poor outcomes of respiratory syncytial virus acute lower respiratory infections in children under 5 years of age in a middle-income tropical country based on the National Public Health Surveillance System

OBJECTIVES

The aim of the present study is to gain insight into the identification of region-specific factors associated with poor outcomes in children under 5 years of age with confirmed respiratory syncytial virus acute lower respiratory infection (RSV-ALRI) living in Colombia, a middle-income country, based on the National Public Health Surveillance System of the country.

METHODS

An analytical cross-sectional study was conducted using epidemiological data from the records of morbidity and mortality of respiratory infections as registered in the surveillance system report of the National Institute of Health of Colombia 2018, including children under 5 years of age with confirmed RSV-ALRI. Predictor variables included demographic and clinical variables, as well as variables measured after hospital attendance. Outcome variables analyzed were respiratory failure, the need for pediatric intensive care unit admission, and mortality.

RESULTS

Of a total of 8470 patients with a diagnosis of ALRI, we selected 1215 (14.3%) that were under 5 years of age and were positive for RSV. After controlling for potential confounders, it was found that age, gender, socioeconomic stratum, incomplete pneumococcal conjugate vaccine 13 immunization for age, cardiac disease, and malnutrition as comorbidities, chest X-ray findings, and development of sepsis independently predicted poor outcomes among the patients analyzed.

CONCLUSIONS

The identified predictors for poor outcomes in RSV-affected children may be helpful for guiding efficient and targeted national and/or regional programs and public policies to assist in achieving Goal 3 of the Sustainable Development Goals adopted by the United Nations in 2015.

Determination of respiratory syncytial virus epidemic seasons by using 95% confidence interval of positivity rates, 2011-2021, Germany

Based on our national outpatient sentinel surveillance, we have developed a novel approach to determine respiratory syncytial virus (RSV) epidemic seasons in Germany by using RSV positivity rate and its lower limit of 95% confidence interval. This method was evaluated retrospectively on nine RSV seasons, and it is also well‐suited to describe off‐season circulation of RSV in near real time as observed for seasons 2020/21 and 2021/22 during the COVID‐19 pandemic. Prospective application is of crucial importance to enable timely actions for health service delivery and prevention.

Mortality Associated With Influenza and Respiratory Syncytial Virus in the US, 1999-2018

IMPORTANCE

Respiratory syncytial virus (RSV) mortality estimates have not been updated since 2009, and no study has assessed changes in influenza mortality after the 2009 pandemic. Updated burden estimates are needed to characterize long-term changes in the epidemiology of these viruses.

OBJECTIVE

To evaluate excess mortality from RSV and influenza in the US from 1999 to 2018.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from 50.3 million US death certificates from 1999 to 2018 to create age-specific linear regression models and assess weekly mortality fluctuations above a seasonal baseline associated with RSV and influenza. Statistical analysis was performed for 1043 weeks from January 3, 1999, to December 29, 2018.

MAIN OUTCOMES AND MEASURES

Excess mortality associated with RSV and influenza estimated from the difference between observed and expected underlying respiratory mortality each season.

RESULTS

There were 50.3 million death certificates (50.1% women and 49.9% men; mean [SD] age at death, 72.7 [18.6] years) included in this analysis, 1.0% for children younger than 1 year and 73.4% for adults aged 65 years or older. A mean of 6549 (95% CI, 6140-6958) underlying respiratory deaths were associated with RSV annually, including 96 (95% CI, 92-99) deaths among children younger than 1 year. For influenza, there were 10 171 (95% CI, 9652-10 691) underlying respiratory deaths per year, with 23 deaths (95% CI, 19-27) among children younger than 1 year. The highest mean mortality rate per 100 000 population for both viruses was among adults aged 65 years or older at 14.7 (95% CI, 13.8-15.5) for RSV and 20.5 (95% CI, 19.4-21.5) for influenza. A lower proportion of influenza deaths occurred among those aged 65 years or older compared with earlier estimates (75.1% [95% CI, 67.4%-82.8%]). Influenza mortality was highest among those aged 65 years or older in seasons when A/H3N2 predominated (18 739 [95% CI, 16 616-21 336] deaths in 2017-2018) and among those aged 5 to 49 years when A/H1N1pdm2009 predominated (1683 [95% CI, 1583-1787] deaths in 2013-2014). Results were sensitive to the choice of mortality outcome and method, with the broadest outcome associated with annual means of 23 352 (95% CI, 21 814-24 891) excess deaths for RSV and 27 171 (95% CI, 25 142-29 199) for influenza.

CONCLUSIONS AND RELEVANCE

This study suggests that RSV poses a greater risk than influenza to infants, while both are associated with substantial mortality among elderly individuals. Influenza has large interannual variability, affecting different age groups depending on the circulating virus. The emergence of the influenza A/H1N1pdm2009 pandemic virus in 2009 shifted mortality toward middle-aged adults, a trend still observed to date. This study's estimates provide a benchmark to evaluate the mortality benefits associated with interventions against respiratory viruses, including new or improved immunization strategies.

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

Background

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

Methods

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

Results

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

Conclusion

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

OUP accepted manuscript

Background

Death certificate data can improve our understanding of the mortality burden associated with respiratory syncytial virus (RSV) and influenza.

Methods

We used International Classification of Diseases, Tenth Revision codes listed on death certificates to characterize deaths from 1999 to 2018 as RSV, influenza, and unspecified bronchiolitis. We described the distribution of each cause of death by age, sex, race/ethnicity, place of death, and contributing causes of death.

Results

Over the 20-year study period, RSV, bronchiolitis, and influenza were listed as the underlying causes of death on 932, 1046, and 52 293 death certificates, respectively. Children <1 year of age accounted for 39% of RSV and bronchiolitis deaths, while 72% of influenza deaths were in adults ≥65 years. Children <1 year were more likely to die outside of the hospital from RSV, bronchiolitis, or influenza compared to all causes (P < .01), and black infants had the highest mortality rate for all 3 causes. Most infants dying from RSV did not have a high-risk condition listed on the death certificate. Death certificates captured 20%–60% of estimated excess RSV-attributable mortality in infants and <1% in seniors.

Conclusions

Thorough reporting on death certificates is an important public health goal, especially as new therapeutics become available. Infants had higher odds of dying out of hospital from respiratory pathogens compared to other causes, and race/ethnicity alone did not explain this disparity.

Respiratory syncytial virus in pediatric influenza-like illness cases in Lombardy, Northern Italy, during seven consecutive winter seasons (from 2014-2015 to 2020-2021)

Introduction

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract illness in young children and can also cause influenza‐like illness (ILI). Here we investigated the epidemiological features of RSV infection in pediatric ILI cases in Lombardy (a region in Northern Italy accounting nearly 10 million inhabitants) from 2014–2015 to 2020–2021 winter seasons.

Material and Methods

Data for this study were retrieved and statistically analyzed from the database of virological influenza surveillance of the regional reference laboratory for Lombardy within the Italian influenza surveillance network (InfluNet).

Results

RSV accounted for nearly 19% of pediatric ILI with a risk of infection nearly two‐fold greater than that of individuals ≥15 years. RSV positivity rate increased to 28% considering 0–5 years old children. Although in children ≤5 years the risk of infection from influenza viruses resulted nearly two‐fold higher than the risk of RSV infection, the age group 4–6 months and 7–12 months showed a five‐fold greater risk of infection from RSV than from influenza. Children ≤5 years of age with pre‐existing underlying health conditions had a nearly five‐fold greater risk of getting RSV infection than otherwise healthy 0–5 years old children. RSV was identified in ILI cases <15 years of age in all considered winter seasons except in the 2020–2021 season.

Discussion

Sentinel surveillance of ILI allowed us to identify groups at higher risk of RSV and influenza infection and to define the start, duration, timing, and intensity of the RSV and influenza community circulation. This surveillance approach can be implemented to assess the RSV circulation and impact in a real‐time manner.

The seasonal behaviour of COVID-19 and its galectin-like culprit of the viral spike

Seasonal behaviour is an attribute of many viral diseases. Like other 'winter' RNA viruses, infections caused by the causative agent of COVID-19, SARS-CoV-2, appear to exhibit significant seasonal changes. Here we discuss the seasonal behaviour of COVID-19, emerging viral phenotypes, viral evolution, and how the mutational landscape of the virus affects the seasonal attributes of the disease. We propose that the multiple seasonal drivers behind infectious disease spread (and the spread of COVID-19 specifically) are in 'trade-off' relationships and can be better described within a framework of a 'triangle of viral persistence' modulated by the environment, physiology, and behaviour. This 'trade-off' exists as one trait cannot increase without a decrease in another. We also propose that molecular components of the virus can act as sensors of environment and physiology, and could represent molecular culprits of seasonality. We searched for flexible protein structures capable of being modulated by the environment and identified a galectin-like fold within the N-terminal domain of the spike protein of SARS-CoV-2 as a potential candidate. Tracking the prevalence of mutations in this structure resulted in the identification of a hemisphere-dependent seasonal pattern driven by mutational bursts. We propose that the galectin-like structure is a frequent target of mutations because it helps the virus evade or modulate the physiological responses of the host to further its spread and survival. The flexible regions of the N-terminal domain should now become a focus for mitigation through vaccines and therapeutics and for prediction and informed public health decision making.

Estimated Cardiorespiratory Hospitalizations Attributable to Influenza and Respiratory Syncytial Virus Among Long-term Care Facility Residents

IMPORTANCE

Older adults residing in long-term care facilities (LTCFs) are at a high risk of being infected with respiratory viruses, such as influenza and respiratory syncytial virus (RSV). Although these infections commonly have many cardiorespiratory sequelae, the national burden of influenza- and RSV-attributable cardiorespiratory events remains unknown for the multimorbid and vulnerable LTCF population.

OBJECTIVE

To estimate the incidence of cardiorespiratory hospitalizations that were attributable to influenza and RSV among LTCF residents and to quantify the economic burden of these hospitalizations on the US health care system by estimating their associated cost and length of stay.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used national Medicare Provider Analysis and Review inpatient claims and Minimum Data Set clinical assessments for 6 respiratory seasons (2011-2017). Long-stay residents of LTCFs were identified as those living in the facility for at least 100 days (index date), aged 65 years or older, and with 6 months of continuous enrollment in Medicare Part A were included. Follow-up occurred from the resident's index date until the first hospitalization, discharge from the LTCF, disenrollment from Medicare, death, or the end of the study. Residents could re-enter the sample; thus, long-stay episodes of care were identified. Data analysis was performed between January 1 and September 30, 2020.

EXPOSURES

Seasonal circulating pandemic 2009 influenza A(H1N1), human influenza A(H3N2), influenza B, and RSV.

MAIN OUTCOMES AND MEASURES

Cardiorespiratory hospitalizations (eg, asthma exacerbation, heart failure) were identified using primary diagnosis codes. Influenza- and RSV-attributable cardiorespiratory events were estimated using a negative binomial regression model adjusted for weekly circulating influenza and RSV testing data. Length of stay and costs of influenza- and RSV-attributable events were then estimated.

RESULTS

The study population comprised 2 909 106 LTCF residents with 3 138 962 long-stay episodes and 5 079 872 person-years of follow-up. Overall, 10 939 (95% CI, 9413-12 464) influenza- and RSV-attributable cardiorespiratory events occurred, with an incidence of 215 (95% CI, 185-245) events per 100 000 person-years. The cost of influenza- and RSV-attributable cardiorespiratory events was $91 055 393 (95% CI, $77 885 316-$104 225 470), and the length of stay was 56 858 (95% CI, 48 757-64 968) days.

CONCLUSIONS AND RELEVANCE

This study found that many cardiorespiratory hospitalizations among LTCF residents in the US were attributable to seasonal influenza and RSV. To minimize the burden these events place on the health care system and residents of LTCFs and to prevent virus transmission, additional preventive measures should be implemented.

Airway Gene Expression Correlates of Respiratory Syncytial Virus Disease Severity and Microbiome Composition in Infants

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of severe respiratory disease in infants. The causes and correlates of severe illness in the majority of infants are poorly defined.

METHODS

We recruited a cohort of RSV-infected infants and simultaneously assayed the molecular status of their airways and the presence of airway microbiota. We used rigorous statistical approaches to identify gene expression patterns associated with disease severity and microbiota composition, separately and in combination.

RESULTS

We measured comprehensive airway gene expression patterns in 106 infants with primary RSV infection. We identified an airway gene expression signature of severe illness dominated by excessive chemokine expression. We also found an association between Haemophilus influenzae, disease severity, and airway lymphocyte accumulation. Exploring the time of onset of clinical symptoms revealed acute activation of interferon signaling following RSV infection in infants with mild or moderate illness, which was absent in subjects with severe illness.

CONCLUSIONS

Our data reveal that airway gene expression patterns distinguish mild/moderate from severe illness. Furthermore, our data identify biomarkers that may be therapeutic targets or useful for measuring efficacy of intervention responses.

Surveillance of respiratory syncytial virus infections in adults, Austria, 2017 to 2019

Respiratory syncytial virus (RSV) testing is generally available in most care centres, but it is rarely performed because clinicians' seldom suspect RSV to be the underlying pathogen in adults with respiratory disease. Here, we evaluate the impact of broad combined influenza/RSV testing on the clinical practice. Overall, 103 patients were tested positively for RSV. Our study indicates that positively tested patients were mostly of advanced age and suffered from chronic diseases. Mortality was significant in our cohort and higher in patients with advanced age. Further, we report a significant increase in detected RSV cases but also in detection rate. Together, these findings suggest that implementation of a combined influenza/RSV testing led to a significant increase in detection rate, supported clinicians establishing the correct diagnosis and allowed a safe and controlled handling of RSV patients.

Recommendations for respiratory syncytial virus surveillance at national level

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

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

A chronicle of SARS-CoV-2: Seasonality, environmental fate, transport, inactivation, and antiviral drug resistance

In this review, we present the environmental perspectives of the viruses and antiviral drugs related to SARS-CoV-2. The present review paper discusses occurrence, fate, transport, susceptibility, and inactivation mechanisms of viruses in the environment as well as environmental occurrence and fate of antiviral drugs, and prospects (prevalence and occurrence) of antiviral drug resistance (both antiviral drug resistant viruses and antiviral resistance in the human). During winter, the number of viral disease cases and environmental occurrence of antiviral drug surge due to various biotic and abiotic factors such as transmission pathways, human behaviour, susceptibility, and immunity as well as cold climatic conditions. Adsorption and persistence critically determine the fate and transport of viruses in the environment. Inactivation and disinfection of virus include UV, alcohol, and other chemical-base methods but the susceptibility of virus against these methods varies. Wastewater treatment plants (WWTPs) are major reserviors of antiviral drugs and their metabolites and transformation products. Ecotoxicity of antiviral drug residues against aquatic organisms have been reported, however more threatening is the development of antiviral resistance, both in humans and in wild animal reservoirs. In particular, emergence of antiviral drug-resistant viruses via exposure of wild animals to high loads of antiviral residues during the current pandemic needs further evaluation.

Current State of Respiratory Syncytial Virus Disease and Management

Respiratory syncytial virus (RSV) is a major cause of hospitalizations due to pneumonia and bronchiolitis. Substantial morbidity and socioeconomic burden are associated with RSV infection worldwide. Populations with higher susceptibility to developing severe RSV include premature infants, children with chronic lung disease of prematurity (CLDP) or congenital heart disease (CHD), elderly individuals aged > 65 years, and immunocompromised individuals. In the pediatric population, RSV can lead to long-term sequelae such as wheezing and asthma, which are associated with increased health care costs and reduced quality of life. Treatment for RSV is mainly supportive, and general preventive measures such as good hygiene and isolation are highly recommended. Although vaccine development for RSV has been a global priority, attempts to date have failed to yield a safe and effective product for clinical use. Currently, palivizumab is the only immunoprophylaxis (IP) available to prevent severe RSV in specific high-risk pediatric populations. Well-controlled, randomized clinical trials have established the efficacy of palivizumab in reducing RSV hospitalization (RSVH) in high-risk infants including moderate- to late-preterm infants. However, the American Academy of Pediatrics (AAP), in its 2014 policy, stopped recommending RSV IP use for ≥ 29 weeks' gestational age infants. Revisions to the AAP policy for RSV IP have largely narrowed the proportion of pediatric patients eligible to receive RSV IP and have been associated with an increase in RSVH and morbidity. On the other hand, after reviewing the recent evidence on RSV burden, the National Perinatal Association, in its 2018 clinical practice guidelines, recommended RSV IP use for a wider pediatric population. As the AAP recommendations drive insurance reimbursements for RSV IP, they should be revised to help further mitigate RSV disease burden.

Increase in Detection of Respiratory Syncytial Virus Among Older Adults in Arizona : An Association With Changes in Testing Practices

OBJECTIVES

Respiratory syncytial virus (RSV) is a common cause of respiratory illness, health care visits, and hospitalizations. Arizona, which began conducting laboratory surveillance in 2004, has noted an increase in RSV cases (defined as a laboratory-positive result) among adults aged ≥65, concurrent with increasing reports from polymerase chain reaction (PCR) testing. We assessed whether the shift in the age distribution of reported RSV cases resulted from a change in RSV testing practices.

METHODS

We used data on laboratory-confirmed RSV cases reported during 2013-2017 from the statewide surveillance system to assess the frequency of test types (rapid antigen, immunofluorescence assay, PCR, and viral culture) by age groups across RSV seasons, and we used logistic regression to estimate changes in odds of receiving a PCR test. We used statewide emergency department hospital discharge data for the same period to assess testing practices regardless of test result.

RESULTS

The overall proportion of PCR tests among RSV cases increased significantly, from 22% in 2013 to 55% in 2017 (P < .001). The percentage of RSV cases among adults aged ≥65 also increased significantly, from 4% in 2013 to 11% in 2017 (P < .001) of RSV cases. Adults aged ≥65 had more than 8 times the odds of positive PCR results than children aged <5, both in crude (odds ratio [OR] = 8.8; 95% CI, 7.6-10.2) and season-adjusted (adjusted OR = 8.1; 95% CI, 7.0-9.5) models. Hospital discharge data corroborated increased RSV PCR usage from 2013 to 2017.

CONCLUSION

Increasing RSV rates among adults aged ≥65 are likely a result of changes in testing practices. This age group may need more targeted intervention and future vaccination.

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.

Short-term effects of specific humidity and temperature on COVID-19 morbidity in select US cities

Little is known about the environmental conditions that drive the spatiotemporal patterns of SARS-CoV-2. Preliminary research suggests an association with meteorological parameters. However, the relationship with temperature and humidity is not yet apparent for COVID-19 cases in US cities first impacted. The objective of this study is to evaluate the association between COVID-19 cases and meteorological parameters in select US cities. A case-crossover design with a distributed lag nonlinear model was used to evaluate the contribution of ambient temperature and specific humidity on COVID-19 cases in select US cities. The case-crossover examines each COVID case as its own control at different time periods (before and after transmission occurred). We modeled the effect of temperature and humidity on COVID-19 transmission using a lag period of 7 days. A subset of 8 cities were evaluated for the relationship with meteorological parameters and 5 cities were evaluated in detail. Short-term exposure to humidity was positively associated with COVID-19 transmission in 4 cities. The associations were small with 3 out of 4 cities exhibiting higher COVID19 transmission with specific humidity that ranged from 6 to 9 g/kg. Our results suggest that weather should be considered in infectious disease modeling efforts. Future work is needed over a longer time period and across different locations to clearly establish the weather-COVID19 relationship.

Seasonality of Respiratory Syncytial Virus Hospitalization

Seasonality of respiratory syncytial virus (RSV) infection is an area of limited knowledge. In this study, we set out to get insight into the epidemic characteristics of RSV. We retrospectively evaluated medical files of 512 hospitalizations in children due to RSV infection from January 2010 to July 2017. In this cohort of patients, there were 96.3% of children below 1 year of age; the median age was 2.8 months. The influence of weather condition during the week of hospitalization (WH) and also the preceding week (WP) on the rate of hospitalizations was also assessed. An overview of morbidity data demonstrates that the epidemic RSV season started from Week 50 of a year and lasts until Week 15 of the following year, with a peak between Week 4 and Week 10. The average monthly percentage rate of morbidity per year was as follows: December, 12.3%; January, 24.5%; February, 29%; and March, 21.7%. Hospitalizations were positively associated with the minimum and maximum outside air temperature during the WH (62.5% and 59.7%, respectively) and the WP (64.3% and 63.4%, respectively) and with relative humidity (WH 23% and WP 29.8%). A weak association with the wind speed was also noticed (WH 22% and WP 21%), while there was no influence of the level of atmospheric pressure on RSV morbidity. We conclude that seasonality of RSV is present between December and April each year, and morbidity is mostly influenced by minimum-maximum outside air temperature changes. Further epidemiological exploration is required to get a better knowledge on both active and passive immunization against RSV.

Determining the seasonality of respiratory syncytial virus in Slovenia

Background

In Slovenia, the respiratory syncytial virus (RSV) surveillance is based on national laboratory data. The weeks with more than 10% of samples tested positive compose RSV epidemic season. The use of real‐time multiplex PCR, which identifies other respiratory pathogens in parallel with RSV, caused more testing but the percentage of RSV positives lowered. The 10% threshold was reached with delay, which raised concern about its suitability for defining RSV seasonality.

Methods

To describe the seasonality of RSV, the onset, offset and duration of the RSV epidemic season across 10 years (from week 40, 2008/2009 to week 39, 2017/2018), four calculative methods were deployed including moving epidemic method, MEM, and epidemiological parameters were compared.

Results

In 10 years, 10 969 (12%) out of 90 264 samples tested positive for RSV. The number of tested samples increased remarkably from the first to last season with a drop in the percentage of positive samples from 23% to 10%. The onset of RSV epidemic varied considerably regardless of the calculative method used (from 10 to 13 weeks). The unevenness in the RSV epidemic season end was also observed. The average duration of RSV epidemic season was the shortest when moving epidemic method has been used (15.7 weeks) and longest with ≥3% method (22.9 weeks).

Conclusion

The ≥3% calculative method could be used as an early warning of the RSV season. However, ≥7% calculative method was found to be reliable enough to define the epidemiological parameters of an ongoing season and to support public health response. The potential of the moving epidemic method should be further explored.

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

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

Air pollution and temperature are associated with increased COVID-19 incidence: A time series study

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Air quality is tightly associated with COVID-19 transmission.

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PM_2.5 and NO₂ strongly promote COVID-19 transmission.

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Temperature is inversely associated with COVID-19 transmission.

Objectives

Although COVID-19 is known to be caused by human-to-human transmission, it remains largely unclear whether ambient air pollutants and meteorological parameters could promote its transmission.

Methods

A retrospective study was conducted to study whether air quality index (AQI), four ambient air pollutants (PM_2.5, PM₁₀, NO₂ and CO) and five meteorological variables (daily temperature, highest temperature, lowest temperature, temperature difference and sunshine duration) could increase COVID-19 incidence in Wuhan and XiaoGan between Jan 26th to Feb 29th in 2020.

Results

First, a significant correlation was found between COVID-19 incidence and AQI in both Wuhan (R² = 0.13, p < 0.05) and XiaoGan (R² = 0.223, p < 0.01). Specifically, among four pollutants, COVID-19 incidence was prominently correlated with PM_2.5 and NO₂ in both cities. In Wuhan, the tightest correlation was observed between NO₂ and COVID-19 incidence (R² = 0.329, p < 0.01). In XiaoGan, in addition to the PM_2.5 (R² = 0.117, p < 0.01) and NO₂ (R² = 0.015, p < 0.05), a notable correlation was also observed between the PM₁₀ and COVID-19 incidence (R² = 0.105, p < 0.05). Moreover, temperature is the only meteorological parameter that constantly correlated well with COVID-19 incidence in both Wuhan and XiaoGan, but in an inverse correlation (p < 0.05).

Conclusions

AQI, PM_2.5, NO₂, and temperature are four variables that could promote the sustained transmission of COVID-19.

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.