Respiratory syncytial virus infection trend is associated with meteorological factors

Clinical and economic burden of respiratory syncytial virus in children aged 0-5 years in Italy

BACKGROUND

Respiratory syncytial virus (RSV) is among the leading causes of hospitalization due to lower respiratory tract infections (LRTIs) in children younger than 5 years worldwide and the second cause of infant death after malaria. RSV infection occurs in almost all the infants before the second year of life with variable clinical severity, often requiring medical assistance. This analysis investigated patients aged 0-5 years with RSV infection focusing on epidemiology, clinical features, and economic burden of RSV-associated hospitalizations in a setting of Italian real clinical practice.

METHODS

An observational retrospective analysis was conducted on administrative databases of healthcare entities covering around 2.6 million residents of whom 120,000 health-assisted infants aged < 5 years. From 2010 to 2018, pediatric patients were included in the presence of hospitalization discharge diagnosis for RSV infections, and RSV-related acute bronchiolitis or pneumonia. Epidemiology, demographics, clinical picture and costs were evaluated in RSV-infected patients, overall and stratified by age ranges (0-1, 1-2, 2-5 years) and compared with an age-matched general population.

RESULTS

Overall 1378 RSV-infected children aged 0-5 years were included. Among them, the annual incidence rate of RSV-related hospitalizations was 175-195/100,000 people, with a peak in neonates aged < 1 year (689-806/100,000). While nearly 85% of infected infants were healthy, the remaining 15% presented previous hospitalization for known RSV risk factors, like preterm birth, or congenital heart, lung, and immune diseases. The economic analysis revealed that direct healthcare costs per patient/year were markedly higher in RSV patients than in the general population (3605€ vs 344€).

CONCLUSIONS

These findings derived from the real clinical practice in Italy confirmed that RSV has an important epidemiological, clinical, and economic burden among children aged 0-5 years. While the complex management of at-risk infants was confirmed, our data also highlighted the significant impact of RSV infection in infants born at term or otherwise healthy, demonstrating that all infants need protection against RSV disease, reducing then the risk of medium and long-term complications, such as wheezing and asthma.

Impact of Subgroup Distribution on Seasonality of Human Respiratory Syncytial Virus: A Global Systematic Analysis

BACKGROUND

Previous studies reported inconsistent findings regarding the association between respiratory syncytial virus (RSV) subgroup distribution and timing of RSV season. We aimed to further understand the association by conducting a global-level systematic analysis.

METHODS

We compiled published data on RSV seasonality through a systematic literature review, and unpublished data shared by international collaborators. Using annual cumulative proportion (ACP) of RSV-positive cases, we defined RSV season onset and offset as ACP reaching 10% and 90%, respectively. Linear regression models accounting for meteorological factors were constructed to analyze the association of proportion of RSV-A with the corresponding RSV season onset and offset.

RESULTS

We included 36 study sites from 20 countries, providing data for 179 study-years in 1995-2019. Globally, RSV subgroup distribution was not significantly associated with RSV season onset or offset globally, except for RSV season offset in the tropics in 1 model, possibly by chance. Models that included RSV subgroup distribution and meteorological factors explained only 2%-4% of the variations in timing of RSV season.

CONCLUSIONS

Year-on-year variations in RSV season onset and offset are not well explained by RSV subgroup distribution or meteorological factors. Factors including population susceptibility, mobility, and viral interference should be examined in future studies.

Assessing the impact of COVID-19 on epidemiological changes of severe pediatric respiratory syncytial virus infections in Malaysia

Introduction

Respiratory syncytial virus (RSV) is one of the leading causes of hospitalization and mortality among children with respiratory tract infections. The non-pharmaceutical preventive measures against severe acute respiratory syndrome coronavirus (COVID-19) may have reduced the transmission of RSV, altering its tropical epidemiological seasonality. Thus, this study represents the first attempt to evaluate changes in RSV epidemiology in the context of COVID-19 pandemic in Malaysia.

Methods

Conducted at a tertiary hospital in Kuala Lumpur, Malaysia, this retrospective study analyzed collated data of children aged <12 years who were admitted for severe respiratory infections from 2017 to 2022. Time series models were used to predict the differences between actual and forecasted RSV cases, while logistic regression assessed the statistical association between RSV and COVID-19.

Results

Among the 4,084 children analyzed, we reported a significant inverse relationship between RSV and COVID-19 infections during the pandemic (2020-2021) (p < 0.05). In 2020, the RSV positivity rate sharply declined to 8.3 and 5.9%, respectively, in the two prominent seasons. Time series analysis showed a tremendous decrease in cases compared to the expected values, with reductions of 98.3% in the first season and 95.7% in the second season. However, following the lifting of the restriction order in 2022, RSV infections rose sharply with a positivity rate of 36.3%, higher than pre-COVID-19 pandemic levels.

Conclusion

This study provides evidence of increasing RSV cases post-COVID-19 pandemic, due to immunity debt. Hence, the healthcare system must be prepared to address future RSV outbreaks with the appropriate implementation of prophylaxis and public health measures.

Respiratory syncytial virus in children: epidemiology and clinical impact post-COVID-19

PURPOSE OF REVIEW

Respiratory syncytial virus (RSV) remains a leading cause of mortality and morbidity worldwide. RSV seasonality was disrupted by COVID-19-associated nonpharmaceutical interventions (NPIs). We review RSV seasonality, molecular epidemiology, clinical manifestations, and community awareness to inform future prevention strategies.

RECENT FINDINGS

An initial reduction of RSV disease observed with NPIs, and subsequent global resurgence was associated with a collapse in genetic diversity. A lack of immunity is suggested to have contributed to the resurgence of RSV cases experienced post COVID-19. The median age of children admitted with RSV increased during the resurgence, likely secondary to the expanded cohort of RSV-immune naive children. The pandemic also played a role in increased community awareness, which can be utilized as part of a coordinated public health effort to introduce prevention strategies. Further education on signs and symptoms of RSV is still required.

SUMMARY

mAbs and maternal vaccines targeting RSV have the potential to reduce paediatric morbidity, however this new era of RSV prevention will require ongoing research to facilitate community awareness and engagement, and better respiratory surveillance. Tackling the global burden of RSV will require a coordinated effort and measures to ensure access and affordability of new prevention strategies.

Circulation of human respiratory syncytial virus and new ON1 genotype in northern Viet Nam, 2017-2020

Objective

Human respiratory syncytial virus (RSV) is a primary cause of paediatric severe acute respiratory infection (SARI) worldwide, especially in developing countries. We investigated the genetic characteristics of RSV in northern Viet Nam to determine the prevalence and distribution of subtypes as well as the diversity and transmission patterns of genotypes.

Methods

In two facilities, from January 2017 to December 2020, 1563 clinical specimens were collected from paediatric patients hospitalized with SARI and tested for RSV. Selected positive samples underwent sequencing analysis targeting the second hypervariable region of the G gene using next-generation sequencing.

Results

The RSV positivity rate was 28.02% (438/1563 samples), and prevalence was highest in children aged < 1 year (43.84%; 192/438). Subtype RSV-A accounted for 53.42% (234/438) of cases, RSV-B for 45.89% (201/438), and there was coinfection in 0.68% (3/438). Both subtypes cocirculated and peaked during August-September in each year of the study. Phylogenetic analysis showed that RSV-A samples belonged to the ON1 genotype, which has three subgenotypes: ON1.1, ON1.2 and ON1.3. However, we did not find the 72-nucleotide duplication in the second hypervariable region of the G gene, a characteristic of genotype ON1, in any RSV-A samples. RSV-B samples belonged to genotype BA9.

Discussion

Our results provide additional molecular characterization of RSV infections in Viet Nam. Specially, our study is the first to report the absence of the 72-nucleotide duplication in the G gene of RSV-A genotype ON1 in Viet Nam, which may help in understanding the genetic evolution of RSV and be useful for vaccine development in the future.

Nonlinear and Multidelayed Effects of Meteorological Drivers on Human Respiratory Syncytial Virus Infection in Japan

In this study, we aimed to characterize the nonlinear and multidelayed effects of multiple meteorological drivers on human respiratory syncytial virus (HRSV) infection epidemics in Japan. The prefecture-specific weekly time-series of the number of newly confirmed HRSV infection cases and multiple meteorological variables were collected for 47 Japanese prefectures from 1 January 2014 to 31 December 2019. We combined standard time-series generalized linear models with distributed lag nonlinear models to determine the exposure-lag-response association between the incidence relative risks (IRRs) of HRSV infection and its meteorological drivers. Pooling the 2-week cumulative estimates showed that overall high ambient temperatures (22.7 °C at the 75th percentile compared to 16.3 °C) and high relative humidity (76.4% at the 75th percentile compared to 70.4%) were associated with higher HRSV infection incidence (IRR for ambient temperature 1.068, 95% confidence interval [CI], 1.056-1.079; IRR for relative humidity 1.045, 95% CI, 1.032-1.059). Precipitation revealed a positive association trend, and for wind speed, clear evidence of a negative association was found. Our findings provide a basic picture of the seasonality of HRSV transmission and its nonlinear association with multiple meteorological drivers in the pre-HRSV-vaccination and pre-coronavirus disease 2019 (COVID-19) era in Japan.

Epidemiology and risk factors of respiratory syncytial virus associated acute respiratory tract infection in hospitalized children younger than 5 years from Sri Lanka

Background

Respiratory syncytial virus (RSV) is the leading cause of acute respiratory tract infections (ARTI) and a major cause of morbidity and mortality in children worldwide.

Aim

This study aimed to describe the prevalence and seasonal patterns of RSV and to determine the actual and predictive association of RSV-associated ARTI and clinical, socio-demographic, and climatic risk factors in children < 5 years.

Methods

Nasopharyngeal aspirates were collected from 500 children < 5 years admitted to the Kegalle General Hospital, Sri Lanka between May 2016 to July 2018. RSV and RSV subtypes were detected using immunofluorescence assay and real time RT-PCR, respectively. Descriptive and inferential statistics were done for the data analysis using Chi-square, Fisher's exact, Kruskal-Wallis test, and multiple binary logistic regression in the statistical package for social sciences (SPSS), version 16.0.

Results

Prevalence of RSV-associated ARTI was 28% in children < 5 years. Both RSV subtypes were detected throughout the study period. RSV-B was the dominant subtype detected with a prevalence of 72.14%. RSV infection in general caused severe respiratory disease leading to hypoxemia. Compared to RSV-B, RSV-A infection had more symptoms leading to hypoxemia. Factors increasing the risk of contracting RSV infection included number of people living (n > 6), having pets at home and inhaling toxic fumes. The inferential analysis predicts RSV infection in children < 5 years with ARTI, with a 75.4% probability with clinical and socio-demographic characteristics like age < 1 year, fever for > 4 days, cough, conjunctivitis, stuffiness, fatigue, six or more people at home, having pets at home and inhaling toxic fumes. Climatic factors like increases in temperature (°C), wind speed (Km/h), wind gust (Km/h), rainfall (mm) and atmospheric pressure (mb) showed a strong correlation with the RSV infection in children.

Determining the Relationship of Meteorological Factors and Severe Pediatric Respiratory Syncytial Virus (RSV) Infection in Central Peninsular Malaysia

Respiratory syncytial virus (RSV) is the most common pathogen causing viral respiratory tract infections among younger children worldwide. The influence of meteorological factors on RSV seasonal activity is well-established for temperate countries; however, in subtropical countries such as Malaysia, relatively stable temperate climates do not clearly support this trend, and the available data are contradictory. Better understanding of meteorological factors and seasonality of RSV will allow effective strategic health management relating to RSV infection, particularly immunoprophylaxis of high-risk infants with palivizumab. Retrospectively, from 2017 to 2021, we examined the association between various meteorological factors (rainfall, rainy days, temperature, and relative humidity) and the incidence of RSV in children aged less than 12 years in Kuala Lumpur, Malaysia. RSV activity peaked in two periods (July to August and October to December), which was significantly correlated with the lowest rainfall (p < 0.007) and number of rainy days (p < 0.005). RSV prevalence was also positively associated with temperature (p < 0.006) and inversely associated with relative humidity (p < 0.006). Based on our findings, we recommend that immunoprophylaxis with palivizumab be administered in children aged less than 2 years where transmission of RSV is postulated to be the highest after the end of two monsoon seasons.

Epidemiology of Respiratory Syncytial Virus-Associated Acute Lower Respiratory Tract Infection among Hospitalized Under-5s in Northwestern Nigeria

Objective Globally, 33 million cases of respiratory syncytial virus (RSV) infections occur annually among under-fives (5s). Ninety-nine percent of deaths from RSV occur in low- and middle-income countries. Under-five pneumonia mortality in Nigeria was estimated at 140,520 in 2017, but RSV epidemiological data are scant due to poor awareness and limited testing. Vaccines for RSV are currently under development and RSV mortality data from this high mortality, low resource setting are essential to maximizing the potential benefit of vaccination as well as promoting vaccine uptake. This study aimed to describe the epidemiology of RSV-associated acute lower respiratory tract infection (ALRTI) in children younger than 5 years in Zaria, Northwestern Nigeria.

Methods A prospective cohort study was conducted among children aged 1 month to 5 years who were hospitalized with ALRTI in the Emergency Pediatric Unit of a tertiary hospital in Zaria from November 2018 to October 2019. Naso-pharyngeal swabs were obtained for RSV testing using a point-of-care immunoassay technique.

Results Thirty-three percent (35/106) of the children had RSV-related ALRTI. The median age of RSV-positive cases was 8 months (IQR 3–14). Two-thirds of children (68.6%, 24/35) were below 12 months. The RSV mortality rate was 5.7% (2/35). RSV occurred in 10 months of the year with peaks in March and July.

Conclusion A third of admitted children with ALRTI were positive for RSV. Therefore RSV significantly contributes to childhood pneumonia and the dual seasonal peak observed in our study may have implications for vaccine implementation.

Circulating pediatric respiratory pathogens in Taiwan during 2020: Dynamic change under low COVID-19 incidence

BACKGROUND

In Taiwan, there were only 799 confirmed COVID-19 cases in 2020. The unique backdrop amidst a pandemic and promotion of nonpharmaceutical interventions generated some distinct changes in the epidemiology of common respiratory pathogens. In this study, we aimed to investigate the dynamic changes in respiratory pathogens in children during 2020.

METHODS

We performed a retrospective cohort study at a tertiary hospital in southern Taiwan during 2020. Patients aged 0-18 years who visited the pediatric emergency department were enrolled. Children who presented with clinical symptoms (fever or respiratory illness) and received nasopharyngeal swabs for multiplex polymerase chain reaction (PCR) were included in our analysis. We also compared respiratory syncytial virus (RSV) trends from previous years by PCR and lateral flow immunochromatographic assays from 2017 to 2020.

RESULTS

A total of 120 children were tested. The overall detection rate was 55%. With strengthened restrictions, the detection rate dropped from 70% to 30%. However, non-enveloped viruses (rhinovirus/enterovirus and adenovirus) were in constant circulation. Upon easing prevention measures, the detection rate remained above 60%, and an outbreak of an enveloped virus (RSV and parainfluenza virus) was noted. Compared with 2017-2019, the cyclical RSV epidemic was delayed, with a large surge in late 2020.

CONCLUSIONS

We observed a constant circulation of non-enveloped viruses when strict nonpharmaceutical interventions were employed and a delayed surge of enveloped viruses during the easing of restrictions. Continuous surveillance and monitoring of the evolutionary dynamics of respiratory viruses is important, while easing restrictions requires balanced judgment.

Prevalence of respiratory viruses among paediatric patients in acute respiratory illnesses in Malaysia

Objectives

Acute respiratory infections (ARIs) are one of the leading causes of childhood morbidity and mortality worldwide. However, there is limited surveillance data on the epidemiological burden of respiratory pathogens in tropical countries like Malaysia. This study aims to estimate the prevalence of respiratory pathogens causing ARIs among children aged <18 years old in Malaysia and their epidemiological characteristics.

Methods

Nasopharyngeal swab specimens received at 12 laboratories located in different states of Malaysia from 2015–2019 were studied. Detection of 18 respiratory pathogens were performed using multiplex PCR.

Results

Data from a total of 23,306 paediatric patients who presented with ARI over a five-year period was studied. Of these, 18538 (79.5%) were tested positive. The most prevalent respiratory pathogens detected in this study were enterovirus/ rhinovirus (6837/ 23000; 29.7%), influenza virus (5176/ 23000; 22.5%) and respiratory syncytial virus (RSV) (3652/ 23000; 15.9%). Throughout the study period, RSV demonstrated the most pronounce seasonality; peak infection occurred during July to September. Whereas the influenza virus was detected year-round in Malaysia. No seasonal variation was noted in other respiratory pathogens. The risk of RSV hospitalisation was found to be significantly higher in children aged less than two years old, whereas hospitalisation rates for the influenza virus peaked at children aged between 3–6 years old.

Conclusion

This study provides insight into the epidemiology and the seasonality of the causative pathogens of ARI among the paediatric population in Malaysia. Knowledge of seasonal respiratory pathogens epidemiological dynamics will facilitate the identification of a target window for vaccination.

Evidence for influenza and RSV interaction from 10 years of enhanced surveillance in Nha Trang, Vietnam, a modelling study

Influenza and Respiratory Syncytial Virus (RSV) interact within their host posing the concern for impacts on heterologous viruses following vaccination. We aimed to estimate the population level impact of their interaction. We developed a dynamic age-stratified two-pathogen mathematical model that includes pathogen interaction through competition for infection and enhanced severity of dual infections. We used parallel tempering to fit its parameters to 11 years of enhanced hospital-based surveillance for acute respiratory illnesses (ARI) in children under 5 years old in Nha Trang, Vietnam. The data supported either a 41% (95%CrI: 36–54) reduction in susceptibility following infection and for 10.0 days (95%CrI 7.1–12.8) thereafter, or no change in susceptibility following infection. We estimate that co-infection increased the probability for an infection in <2y old children to be reported 7.2 fold (95%CrI 5.0–11.4); or 16.6 fold (95%CrI 14.5–18.4) in the moderate or low interaction scenarios. Absence of either pathogen was not to the detriment of the other. We find stronger evidence for severity enhancing than for acquisition limiting interaction. In this setting vaccination against either pathogen is unlikely to have a major detrimental effect on the burden of disease caused by the other.

Influenza and Respiratory Syncytial Virus (RSV) cause large burdens of disease. Instead of acting independently, there may be short term cross-protection between them. The evidence of this to date comes from ecological studies which are unable to test the mechanism, or biological studies that are unable to determine the population level impacts of such cross-protection. We create a mathematical model that simulates the circulation of these two viruses, and allows for cross-protection between them. We then fit this model to hospital reported cases of confirmed infection from Nha Trang, Vietnam in order to estimate whether any cross-protection exists in this setting. We show that there are two possibilities—either no interaction or moderate interaction that can result in the observed circulation patterns. However, we further show that co-infection results in an increased reporting rate, presumably due to increased severity.

Effects and Interaction of Meteorological Parameters on Influenza Incidence During 2010-2019 in Lanzhou, China

Background

Influenza is a seasonal infectious disease, and meteorological parameters critically influence the incidence of influenza. However, the meteorological parameters linked to influenza occurrence in semi-arid areas are not studied in detail. This study aimed to clarify the impact of meteorological parameters on influenza incidence during 2010-2019 in Lanzhou. The results are expected to facilitate the optimization of influenza-related public health policies by the local healthcare departments.

Methods

Descriptive data related to influenza incidence and meteorology during 2010-2019 in Lanzhou were analyzed. The exposure-response relationship between the risk of influenza occurrence and meteorological parameters was explored according to the distributed lag no-linear model (DLNM) with Poisson distribution. The response surface model and stratified model were used to estimate the interactive effect between relative humidity (RH) and other meteorological parameters on influenza incidence.

Results

A total of 6701 cases of influenza were reported during 2010-2019. DLNM results showed that the risk of influenza would gradually increase as the weekly mean average ambient temperature (AT), RH, and absolute humidity (AH) decrease at lag 3 weeks when they were lower than 12.16°C, 51.38%, and 5.24 g/m³, respectively. The low Tem (at 5th percentile, P₅) had the greatest effect on influenza incidence; the greatest estimated relative risk (RR) was 4.54 (95%CI: 3.19-6.46) at cumulative lag 2 weeks. The largest estimates of RRs for low RH (P₅) and AH (P₅) were 4.81 (95%CI: 3.82-6.05) and 4.17 (95%CI: 3.30-5.28) at cumulative lag 3 weeks, respectively. An increase in AT by 1°C led to an estimates of percent change (95%CI) of 3.12% (-4.75% to -1.46%) decrease in the weekly influenza case counts in a low RH environment. In addition, RH showed significant interaction with AT and AP on influenza incidence but not with wind speed.

Conclusion

This study indicated that low AT, low humidity (RH and AH), and high air pressure (AP) increased the risk of influenza. Moreover, the interactive effect of low RH with low AT and high AP can aggravate the incidence of influenza.

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

Introduction

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

Methods

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

Findings

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

Conclusion

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

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

Modeling and Forecasting Cases of RSV Using Artificial Neural Networks

In this paper, we study and present a mathematical modeling approach based on artificial neural networks to forecast the number of cases of respiratory syncytial virus (RSV). The number of RSV-positive cases in most of the countries around the world present a seasonal-type behavior. We constructed and developed several multilayer perceptron (MLP) models that intend to appropriately forecast the number of cases of RSV, based on previous history. We compared our mathematical modeling approach with a classical statistical technique for the time-series, and we concluded that our results are more accurate. The dataset collected during 2005 to 2010 consisting of 312 weeks belongs to Bogotá D.C., Colombia. The adjusted MLP network that we constructed has a fairly high forecast accuracy. Finally, based on these computations, we recommend training the selected MLP model using 70% of the historical data of RSV-positive cases for training and 20% for validation in order to obtain more accurate results. These results are useful and provide scientific information for health authorities of Colombia to design suitable public health policies related to RSV.

Upsurge of human rhinovirus infection followed by a delayed seasonal respiratory syncytial virus infection in Thai children during the coronavirus pandemic

BACKGROUND

Respiratory syncytial virus (RSV) and human rhinovirus (HRV) commonly cause influenza-like illness in young children. The global coronavirus pandemic beginning in 2020 altered the seasonality and prevalence of these respiratory infections in Thailand. We aimed to characterize the upsurge of HRV and the subsequent RSV infection observed among young children who sought medical care at a hospital in Bangkok.

METHODS

From July to December 2020, nasopharyngeal swabs from children ≤5 years of age presented with influenza-like illness were tested for RSV and HRV using reverse-transcription polymerase chain reaction. Positive samples were Sanger sequenced. Genotyping was performed using sequence and phylogenetic analysis.

RESULTS

Upsurge of HRV infection began in July and was subsequently replaced by a surge of RSV infection from September onward. In 6 months, HRV was detected in 27.5% (158/574) of the samples, of which 44% (69/158) were HRV-A, 7% (11/158) were HRV-B, and 36% (57/158) were HRV-C. Meanwhile, RSV was detected in 40.4% (232/574) of the samples, of which 78% (181/232) were RSV-A and 6% (14/232) were RSV-B. RSV peaked in October 2020, approximately 2 months later than typically seen in previous years. All RSV-A were of subgenotype ON1. Codetection of HRV and RSV was found in 5.1% (29/574).

CONCLUSIONS

HRV and RSV infection among young children coincided with relaxed local coronavirus public health measures, including the return to in-class schooling. The delayed RSV season in 2020 was predominantly associated with RSV-A.

Decreased human respiratory syncytial virus activity during the COVID-19 pandemic in Japan: an ecological time-series analysis

BACKGROUND

Non-pharmaceutical interventions (NPIs), such as sanitary measures and travel restrictions, aimed at controlling the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), may affect the transmission dynamics of human respiratory syncytial virus (HRSV). We aimed to quantify the contribution of the sales of hand hygiene products and the number of international and domestic airline passenger arrivals on HRSV epidemic in Japan.

METHODS

The monthly number of HRSV cases per sentinel site (HRSV activity) in 2020 was compared with the average of the corresponding period in the previous 6 years (from January 2014 to December 2020) using a monthly paired t-test. A generalized linear gamma regression model was used to regress the time-series of the monthly HRSV activity against NPI indicators, including sale of hand hygiene products and the number of domestic and international airline passengers, while controlling for meteorological conditions (monthly average temperature and relative humidity) and seasonal variations between years (2014-2020).

RESULTS

The average number of monthly HRSV case notifications in 2020 decreased by approximately 85% (p < 0.001) compared to those in the preceding 6 years (2014-2019). For every average ¥1 billion (approximately £680,000/$9,000,000) spent on hand hygiene products during the current month and 1 month before there was a 0.29% (p = 0.003) decrease in HRSV infections. An increase of average 1000 domestic and international airline passenger arrivals during the previous 1-2 months was associated with a 3.8 × 10^- 4% (p < 0.001) and 1.2 × 10^- 3% (p < 0.001) increase in the monthly number of HRSV infections, respectively.

CONCLUSIONS

This study suggests that there is an association between the decrease in the monthly number of HRSV cases and improved hygiene and sanitary measures and travel restrictions for COVID-19 in Japan, indicating that these public health interventions can contribute to the suppression of HRSV activity. These findings may help in public health policy and decision making.

Characteristics, complications, and mortality of respiratory syncytial virus compared with influenza infections in hospitalized adult patients in Thailand

INTRODUCTION

RSV is increasingly recognized in adults. An improved understanding of clinical manifestations and complications may facilitate diagnosis and management.

METHODS

This was a retrospective study of hospitalized patients aged ≥ 18 years with RSV or influenza infection at Siriraj hospital, Thailand between January 2014 and December 2017.

RESULTS

RSV and/or influenza were detected by RT-PCR in 570 (20.1%) of 2836 patients. After excluding patients coinfected with influenza A and B (n = 5), and with influenza and RSV (n = 3), 141 (5.0%) RSV and 421 (14.8%) influenza patients were analyzed. Over the study period, RSV circulated during the rainy season and peaked in September or October. Patients with RSV were older than patients with influenza and presented significantly less myalgia and fever, but more wheezing. Pneumonia was the most common complication, occurring in 110 (78.0%) of RSV cases and in 295 (70.1%) of influenza cases (p = 0.069). Cardiovascular complications were found in 30 (21.3%) RSV and 96 (22.8%) influenza (p = 0.707), and were reasons for admission in 15 (10.6%) RSV and 50 (11.9%) influenza. The in-hospital mortality rates for RSV (17; 12.1%) and influenza (60; 14.3%) were similar (p = 0.512).

CONCLUSIONS

In Thailand, RSV is a less common cause of adult hospitalization than influenza, but pulmonary and cardiovascular complications, and mortality are similar. Clinical manifestations cannot reliably distinguish between RSV and influenza infection; laboratory-confirmed diagnosis is needed.

Increased duration of pollen and mold exposure are linked to climate change

Pollen and molds are environmental allergens that are affected by climate change. As pollen and molds exhibit geographical variations, we sought to understand the impact of climate change (temperature, carbon dioxide (CO₂), precipitation, smoke exposure) on common pollen and molds in the San Francisco Bay Area, one of the largest urban areas in the United States. When using time-series regression models between 2002 and 2019, the annual average number of weeks with pollen concentrations higher than zero increased over time. For tree pollens, the average increase in this duration was 0.47 weeks and 0.51 weeks for mold spores. Associations between mold, pollen and meteorological data (e.g., precipitation, temperature, atmospheric CO₂, and area covered by wildfire smoke) were analyzed using the autoregressive integrated moving average model. We found that peak concentrations of weed and tree pollens were positively associated with temperature (p < 0.05 at lag 0–1, 0–4, and 0–12 weeks) and precipitation (p < 0.05 at lag 0–4, 0–12, and 0–24 weeks) changes, respectively. We did not find clear associations between pollen concentrations and CO₂ levels or wildfire smoke exposure. This study’s findings suggest that spore and pollen activities are related to changes in observed climate change variables.

The Association between Weather Conditions and Admissions to the Paediatric Intensive Care Unit for Respiratory Syncytial Virus Bronchiolitis

Respiratory syncytial virus (RSV) bronchiolitis is a leading cause of global child morbidity and mortality. Every year, seasonal RSV outbreaks put high pressure on paediatric intensive care units (PICUs) worldwide, including in the Netherlands, and this burden appears to be increasing. Weather conditions have a strong influence on RSV activity, and climate change has been proposed as a potential important determinant of future RSV-related health care utilisation. In this national study spanning a total of 13 years with 2161 PICU admissions for RSV bronchiolitis, we aimed (1) to identify meteorological variables that were associated with the number of PICU admissions for RSV bronchiolitis in the Netherlands and (2) to determine if longitudinal changes in these variables occurred over time as a possible explanation for the observed increase in PICU burden. Poisson regression modelling was used to identify weather variables (aggregated in months and weeks) that predicted PICU admissions, and linear regression analysis was used to assess changes in the weather over time. Maximum temperature and global radiation best predicted PICU admissions, with global radiation showing the most stable strength of effect in both month and week data. However, we did not observe a significant change in these weather variables over the 13-year time period. Based on our study, we could not identify changing weather conditions as a potential contributing factor to the increased RSV-related PICU burden in the Netherlands.

Epidemiology and Seasonality of Childhood Respiratory Syncytial Virus Infections in the Tropics

Infections caused by respiratory syncytial virus (RSV) are a major cause of morbidity and mortality in young children worldwide. Understanding seasonal patterns of region-specific RSV activity is important to guide resource allocation for existing and future treatment and prevention strategies. The decades of excellent RSV surveillance data that are available from the developed countries of the world are incredibly instructive in advancing public health initiatives in those regions. With few exceptions, these developed nations are positioned geographically across temperate regions of the world. RSV surveillance across tropical regions of the world has improved in recent years, but remains spotty, and where available, still lacks the necessary longitudinal data to determine the amount of seasonal variation expected over time. However, existing and emerging data collected across tropical regions of the world do indicate that patterns of infection are often quite different from those so well described in temperate areas. Here, we provide a brief summary regarding what is known about general patterns of RSV disease activity across tropical Asia, Africa and South America, then offer additional country-specific details using examples where multiple reports and/or more robust surveillance data have become available.