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Background: Respiratory syncytial virus (RSV) infections are one of the leading causes of lower respiratory tract infections and have a major burden on society. For prevention and control to be deployed effectively, an improved understanding of the seasonality of RSV is necessary., Objectives: The main objective of this study was to contribute to a better understanding of RSV seasonality by examining the GERi multi-country surveillance dataset., Methods: RSV seasons were included in the analysis if they contained ≥100 cases. Seasonality was determined using the "average annual percentage" method. Analyses were performed at a subnational level for the United States and Brazil., Results: We included 601 425 RSV cases from 12 countries. Most temperate countries experienced RSV epidemics in the winter, with a median duration of 10-21 weeks. Not all epidemics fit this pattern in a consistent manner, with some occurring later or in an irregular manner. More variation in timing was observed in (sub)tropical countries, and we found substantial differences in seasonality at a subnational level. No association was found between the timing of the epidemic and the dominant RSV subtype., Conclusions: Our findings suggest that geographical location or climatic characteristics cannot be used as a definitive predictor for the timing of RSV epidemics and highlight the need for (sub)national data collection and analysis., (© 2021 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

Objective: To describe the characteristics of healthcare workers (HCWs) infected with COVID-19 and to examine their sources of exposure., Methods: A descriptive cross-sectional study using data extracted from the centralized disease notification system comprising individuals confirmed with COVID-19 in Singapore between 23 January and 17 April 2020. Occupation of HCWs was categorized into six categories. Their job nature was classified into "frontline" or "back-end" based on the frequency of direct patient contact, and source of exposure was classified as family/household, social interaction or workplace. Chi-square and median tests were used to identify differences between categorical groups and sample medians, respectively., Results: A total of 88 (1.7%) HCWs were identified from 5,050 cases. Their median age was 35 years. Chinese and Indians constituted 42.0% and 31.8%, respectively, and 43.2% were foreigners. The majority (63.6%) was serving at frontlines handling patient-facing duties, 15.9% were doctors, 11.4% were nurses and 44.3% were ancillary staff. About 81.8% acquired the infection locally, of which 40.3% did not have a clearly identifiable source of exposure. Exposure from the family/household was most common (27.8%), followed by workplace (16.7%) and social interaction (15.3%). All HCWs were discharged well with no mortality; three (3.4%) were ever admitted to intensive care unit and required increased care., Conclusion: Healthcare workers accounted for a small proportion of COVID-19 cases in Singapore with favourable outcomes. The possibility of transmission resulting from family/household exposure and social interactions highlights the need to maintain strict vigilance and precautionary measures at all times beyond the workplace., (© 2020 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

Background: Respiratory syncytial virus (RSV) is an important respiratory pathogen that affects people of all ages., Objectives: We examined the patterns of RSV circulation in 2014-2018, and investigated their age-specific differences in tropical Singapore., Methods: Nasopharyngeal and/or throat swabs were taken from outpatient attendees for the national influenza virological surveillance among those who presented with acute respiratory illness in the community. Specimens tested negative for influenza were then tested for RSV and other respiratory pathogens., Results: Among 8436 influenza-negative specimens tested during the five-year period, 5.8% (95% confidence interval 5.3%-6.3%) were positive for RSV. The peak of RSV activity occurred around middle of the year. The age-specific proportion of RSV detections showed a reverse J-shaped pattern; RSV positivity was the highest in young children ≤2 years of age (10.9%), followed by those aged 3-5 years (6.4%) and persons aged ≥65 years (5.3%), while the nadir was observed in the age group of 15-24 years (1.2%). RSV type A was predominantly circulating in children ≤5 years of age from 2014 to 2015 and 2017, whereas in 2016, they were more affected by type B., Conclusion: Respiratory syncytial virus was more frequently detected among the two age groups that have been recommended for influenza vaccination; persons ≥65 years of age and children 6 months to <5 years of age. Characterisation of RSV activity in the community helps to better inform public health policies for effective prevention and control interventions., (© 2020 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

Background: We report our experience in evaluating the severity of local influenza epidemics using the World Health Organization Pandemic Influenza Severity Assessment framework., Methods: We assessed the severity of influenza by monitoring indicators of influenza transmissibility, seriousness of disease and impact on healthcare resource utilisation. Indicators were described by various parameters collected weekly from eight government hospitals, 20 government and 30 private primary care clinics, and the national public health laboratory. Transmissibility and seriousness of disease indicators were each represented by multiple parameters, and alert thresholds were set at the 70th and 90th percentile of a parameter's past 2-year surveillance data. We derived a collective measure for each indicator using the average percentile rank of the related parameters. Alert thresholds for the single impact parameter were set at predefined values and evaluated for its sensitivity, specificity and positive predictive value., Results: For the transmissibility and seriousness of disease parameters, calculation of the percentile rank was simple and independent of a parameter's underlying distribution. For the impact parameter, predefined alert thresholds had high sensitivity and specificity (>80%) but low positive predictive value (15%-30%). Assessment scales were used to qualitatively classify the activity of an indicator as low, moderate or high together with a confidence level., Conclusion: We applied different methods for threshold setting depending on the attributes of each parameter and indicator. For indicators represented by multiple parameters, an aggregated assessment of the indicator's level of activity and confidence level of the assessment was needed for effective reporting., (© 2019 The Authors Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.)