Community factors associated with local epidemic timing of respiratory syncytial virus: A spatiotemporal modeling study

Resurgence and seasonal patterns of RSV-B during the COVID-19 era: an 18-year retrospective hospital-based study

Respiratory syncytial virus (RSV) is a leading cause of severe respiratory infections, particularly in infants, older adults, and immunocompromised individuals. In this study, we aimed to characterize the epidemiology of RSV subtype B (RSV-B), which remains relatively understudied compared with subtype A despite its clinical significance. We conducted a retrospective analysis of laboratory-confirmed RSV-B infections over 18 years (2007-2024) at a tertiary hospital in South Korea. The dataset included 23,284 cases analyzed for age distribution, seasonality, sex differences, and the impact of the coronavirus disease 2019 (COVID-19) pandemic. The highest positivity rate was observed in infants under 1 year (12.7%, p < 0.001), followed by ages 1-19 years (6.9%). RSV-B incidence peaked in winter (11.9%) and autumn (8.7%), with significant seasonal variation (p < 0.001). No statistically significant sex-based difference was observed (male: 6.1%, female: 6.7%; p = 0.102). Positivity rates declined markedly during the COVID-19 pandemic (2019-2022), likely due to non-pharmaceutical interventions. These findings clarify RSV-B's distinct epidemiology and underscore the need for subtype-specific surveillance, targeted vaccination, and adaptable public health strategies. This study provides evidence to improve outbreak prediction, identify high-risk groups, and optimize clinical and preventive responses to RSV-B.

Unseasonal respiratory syncytial virus epidemics during the COVID-19 pandemic: Relationship between climatic factors and epidemic strain switching

OBJECTIVES

The COVID-19 pandemic has altered respiratory syncytial virus (RSV) epidemic patterns. However, the influence of climatic and virological factors on RSV outbreaks remains unclear. We examined RSV incidence in Okinawa, Japan; Taiwan, China; and Florida, USA before and after the COVID-19 pandemic, focusing on the effects of population mobility and climate.

METHODS

We analysed correlations among RSV incidence, human mobility, and climate before and after the pandemic. Additionally, we conducted a phylogenetic analysis of the second variable region of RSV G proteins using viral genomes isolated from patients with acute respiratory tract infections in Okinawa.

RESULTS

Annual RSV epidemics in Okinawa were not correlated with post-pandemic human mobility. The temperature and humidity ranges at the onset of RSV epidemics differed between the pre- and post-pandemic periods, with decreased standard deviations. Genetic analysis of RSV strains from 2020 to 2022 revealed a cluster with low genetic diversity, which differed markedly from pre-2019 and 2023 prevalent strains.

CONCLUSION

Reduced human migration led to an RSV epidemic caused by an indigenous endemic strain, highlighting the natural relationship between epidemics and climatic factors. These findings could aid in developing effective prediction and control programs for RSV epidemics and optimising vaccine programs.

Respiratory syncytial virus: health burden, disease prevention, and treatment-recent progress and lessons learned

Respiratory syncytial virus (RSV), a negative-sense single-stranded RNA virus of the Pneumoviridae family, represents the most important pathogen of lower respiratory tract infections in young infants causing yearly epidemics. RSV is also an important respiratory viral pathogen for older subjects, which is second only to seasonal influenza virus infections. RSV represents a substantial public health burden with respect to morbidity and mortality, particularly in developing countries. Prevention and treatment options would therefore lessen the global disease burden. A formalin-inactivated RSV vaccine in the 1960s induced an enhanced disease upon exposure to natural RSV. After this tragical vaccine failure, it took nearly five decades of intensive research before prevention tools were approved by health authorities. The lead was taken by passive immunity approaches with injected monoclonal antibodies directed against the fusion protein F of RSV. The elucidation of the three-dimensional structure of the F protein revealed pre- and postfusion conformations. Subsequently, structure-based antigen engineering of the F protein paved the way for development of a prophylactic vaccine. In 2023, RSV vaccines were approved for maternal vaccination to protect young infants by placental transfer of antibodies and for vaccination in older subjects. Antiviral drugs that target the RSV fusion process, the RSV replicase, or the cytoplasmic viral factories are in development. Important research papers leading to these developments are reviewed here.

Understanding the local-level variations in seasonality of human respiratory syncytial virus infection: a systematic analysis

BACKGROUND

While previous reports characterised global and regional variations in RSV seasonality, less is known about local variations in RSV seasonal characteristics. This study aimed to understand the local-level variations in RSV seasonality and to explore the role of geographical, meteorological, and socio-demographic factors in explaining these variations.

METHODS

We conducted a systematic literature review to identify published studies reporting data on local-level RSV season onset, offset, or duration for at least two local sites. In addition, we included three datasets of RSV activity from Japan, Spain, and Scotland with available site-specific data. RSV season onset, offset, and duration were defined using the annual cumulative proportion method. We estimated between-site variations within a region using the earliest onset, the earliest offset, and the shortest duration of RSV season of that region as the references and synthesised the variations across regions by a multi-level mixed-effects meta-analysis. Using the three datasets from Japan, Spain and Scotland, we applied linear regression models with clustered standard errors to explore the association of geographical, meteorological, and socio-demographic factors with the season onset and offset, respectively.

RESULTS

We included 7 published studies identified from the systematic literature search. With the additional 3 datasets, these data sources covered 888,447 RSV-positive cases from 101 local study sites during 1995 to 2020. Local-level variations in RSV season within a region were estimated to be 6 weeks (41 days, 95% CI: 25-57) for season onset, 5 weeks (32 days, 13-50) for season offset, and 6 weeks (40 days, 20-59) for season duration, with substantial differences across years. Multiple factors, such as temperature, relative humidity, wind speed, annual household income, population size, latitude, and longitude, could jointly explain 66% to 84% and 35% to 49% of the variations in season onset and offset, respectively, although their individual effects varied by individual regions.

CONCLUSIONS

Local-level variations in RSV season onset could be as much as 6 weeks, which could be influenced by meteorological, geographical, and socio-demographic factors. The reported variations in this study could have important implications for local-level healthcare resources planning and immunisation strategy.

TRIAL REGISTRATION

PROSPERO CRD42023482432.

Exploring RSV transmission patterns in different age groups in the United States

Respiratory syncytial virus (RSV) infections are a significant public health concern for pediatric populations and older adults, with seasonal winter outbreaks in the United States (US). Little is known about the timing of RSV epidemics across age groups and the relative contribution of within-group and between-group transmission of RSV in each age group. The lack of understanding of age-specific RSV transmission patterns limits our ability to inform vaccination policies. In this study, we examine the timing and transmission patterns of RSV epidemics across different age groups in 12 US states from 2018 to 2024. We found that infants under 1 year and young children aged 1-4 years experienced the earliest epidemic timing, while the elderly group had the latest. Using a semi-mechanistic age-structured spatiotemporal model, we further showed that between-group transmission greatly contributes (>50%) to the burden of RSV hospitalizations for children under 1, school-age children aged 5-17, and adults aged 18-64. By contrast, incidence in the elderly group (above 65 years) was primarily driven by transmission within the age group. Our findings indicate that distinct age groups play unique roles in propagating RSV epidemics in the US, with age-specific transmission patterns that can guide more effective RSV vaccination policies.

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.

Spatial and temporal variation in respiratory syncytial virus (RSV) subtype RNA in wastewater and relation to clinical specimens

Respiratory syncytial virus (RSV) causes a large burden of respiratory illness globally. It has two subtypes, RSV A and RSV B, but little is known regarding the predominance of these subtypes during different seasons and their impact on morbidity and mortality. Using molecular methods, we quantified RSV A and RSV B RNA in wastewater solids across multiple seasons and metropolitan areas to gain insight into the predominance of RSV subtypes. We determined the predominant subtype for each group using the proportion of RSV A to total RSV (RSV A + RSV B) in each wastewater sample (PA,WW) and conducted a comparative analysis temporally, spatially, and against clinical specimens. A median PA,WW of 0.00 in the first season and 0.58 in the second season indicated a temporal shift in the predominant subtype. Spatially, while we observed dominance of the same subtype, PA,WW was higher in some areas (PA,WW = 0.58-0.88). The same subtype predominated in wastewater and clinical samples, but clinical samples showed higher levels of RSV A (RSV A positivity in clinical samples = 0.79, median PA,WW = 0.58). These results suggest that wastewater, alongside clinical data, holds promise for enhanced subtype surveillance.IMPORTANCERespiratory syncytial virus (RSV) causes a large burden of respiratory illness globally. It has two subtypes, RSV A and RSV B, but little is known regarding the predominance of these subtypes during different seasons and their impact on morbidity and mortality. The study illustrates that information on subtype predominance can be gleaned from wastewater. As a biological composite sample from the entire contributing population, wastewater monitoring of RSV A and B can complement clinical surveillance of RSV.

Comparison of the Burden and Temporal Pattern of Hospitalisations Associated With Respiratory Syncytial Virus (RSV) Before and After COVID-19 in New Zealand

BACKGROUND

Changes in the epidemiology of illnesses caused by respiratory syncytial virus (RSV) infection following the COVID-19 pandemic are reported. The New Zealand (NZ) COVID-19 situation was unique; RSV community transmission was eliminated with the 2020 border closure, with a rapid and large increase in hospitalizations following the relaxation of social isolation measures and the opening of an exclusive border with Australia.

METHODS

This active population-based surveillance compared the age-specific incidence and seasonality of RSV-associated hospitalizations in Auckland, NZ, for 2 years before and after the 2020 border closures. Hospitalisation rates between years were compared by age, ethnicity (European/other, Māori, Pacific and Asian) and socioeconomic group (1 = least, 5 = most deprived).

RESULTS

There was no RSV transmission in 2020. In all other years, hospitalisation rates were highest for people of Pacific versus other ethnic groups and for people living in the most deprived quintile of households. RSV hospitalisation rates were higher in 2021 and 2022 than in 2018-19. The epidemic peak was higher in 2021, but not 2022, and the duration was shorter than in 2018-19. In 2021, the increase in RSV hospitalisation rates was significant across all age, sex, ethnic and socioeconomic groups. In 2022, the increase in hospitalisation rates was only significant in one age (1- < 3 years), one ethnic (Asian) and one socioeconomic group (quintile 2).

CONCLUSIONS

COVID pandemic responses altered RSV-related hospitalisation seasonal patterns. Atypical features of RSV hospitalisation epidemiology were the increase in rates in older children and young adults, which lessened in 2022. Despite these variations, RSV hospitalisations in NZ continue to disproportionately affect individuals of Pacific ethnicity and those living in more socioeconomically deprived households. Whilst future public health strategies focused on RSV disease mitigation need to consider the potential shifts in epidemiological patterns when the transmission is disrupted, these variances must be considered in the context of longer-standing patterns of unequal disease distribution.

Global patterns of rebound to normal RSV dynamics following COVID-19 suppression

BACKGROUND

Annual epidemics of respiratory syncytial virus (RSV) had consistent timing and intensity between seasons prior to the SARS-CoV-2 pandemic (COVID-19). However, starting in April 2020, RSV seasonal activity declined due to COVID-19 non-pharmaceutical interventions (NPIs) before re-emerging after relaxation of NPIs. We described the unusual patterns of RSV epidemics that occurred in multiple subsequent waves following COVID-19 in different countries and explored factors associated with these patterns.

METHODS

Weekly cases of RSV from twenty-eight countries were obtained from the World Health Organisation and combined with data on country-level characteristics and the stringency of the COVID-19 response. Dynamic time warping and regression were used to cluster time series patterns and describe epidemic characteristics before and after COVID-19 pandemic, and identify related factors.

RESULTS

While the first wave of RSV epidemics following pandemic suppression exhibited unusual patterns, the second and third waves more closely resembled typical RSV patterns in many countries. Post-pandemic RSV patterns differed in their intensity and/or timing, with several broad patterns across the countries. The onset and peak timings of the first and second waves of RSV epidemics following COVID-19 suppression were earlier in the Southern than Northern Hemisphere. The second wave of RSV epidemics was also earlier with higher population density, and delayed if the intensity of the first wave was higher. More stringent NPIs were associated with lower RSV growth rate and intensity and a shorter gap between the first and second waves.

CONCLUSION

Patterns of RSV activity have largely returned to normal following successive waves in the post-pandemic era. Onset and peak timings of future epidemics following disruption of normal RSV dynamics need close monitoring to inform the delivery of preventive and control measures.

Seasonality of influenza-like illness and short-term forecasting model in Chongqing from 2010 to 2022

BACKGROUND

Influenza-like illness (ILI) imposes a significant burden on patients, employers and society. However, there is no analysis and prediction at the hospital level in Chongqing. We aimed to characterize the seasonality of ILI, examine age heterogeneity in visits, and predict ILI peaks and assess whether they affect hospital operations.

METHODS

The multiplicative decomposition model was employed to decompose the trend and seasonality of ILI, and the Seasonal Auto-Regressive Integrated Moving Average with exogenous factors (SARIMAX) model was used for the trend and short-term prediction of ILI. We used Grid Search and Akaike information criterion (AIC) to calibrate and verify the optimal hyperparameters, and verified the residuals of the multiplicative decomposition and SARIMAX model, which are both white noise.

RESULTS

During the 12-year study period, ILI showed a continuous upward trend, peaking in winter (Dec. - Jan.) and a small spike in May-June in the 2-4-year-old high-risk group for severe disease. The mean length of stay (LOS) in ILI peaked around summer (about Aug.), and the LOS in the 0-1 and ≥ 65 years old severely high-risk group was more irregular than the others. We found some anomalies in the predictive analysis of the test set, which were basically consistent with the dynamic zero-COVID policy at the time.

CONCLUSION

The ILI patient visits showed a clear cyclical and seasonal pattern. ILI prevention and control activities can be conducted seasonally on an annual basis, and age heterogeneity should be considered in the health resource planning. Targeted immunization policies are essential to mitigate potential pandemic threats. The SARIMAX model has good short-term forecasting ability and accuracy. It can help explore the epidemiological characteristics of ILI and provide an early warning and decision-making basis for the allocation of medical resources related to ILI visits.

Modeling the impact of COVID-19 nonpharmaceutical interventions on respiratory syncytial virus transmission in South Africa

Background

The South African government employed various nonpharmaceutical interventions (NPIs) to reduce the spread of SARS-CoV-2. Surveillance data from South Africa indicates reduced circulation of respiratory syncytial virus (RSV) throughout the 2020-2021 seasons. Here, we use a mechanistic transmission model to project the rebound of RSV in the two subsequent seasons.

Methods

We fit an age-structured epidemiological model to hospitalization data from national RSV surveillance in South Africa, allowing for time-varying reduction in RSV transmission during periods of COVID-19 circulation. We apply the model to project the rebound of RSV in the 2022 and 2023 seasons.

Results

We projected an early and intense outbreak of RSV in April 2022, with an age shift to older infants (6-23 months old) experiencing a larger portion of severe disease burden than typical. In March 2022, government alerts were issued to prepare the hospital system for this potentially intense outbreak. We then assess the 2022 predictions and project the 2023 season. Model predictions for 2023 indicate that RSV activity has not fully returned to normal, with a projected early and moderately intense wave. We estimate that NPIs reduced RSV transmission between 15% and 50% during periods of COVID-19 circulation.

Conclusions

A wide range of NPIs impacted the dynamics of the RSV outbreaks throughout 2020-2023 in regard to timing, magnitude, and age structure, with important implications in a low- and middle-income countries (LMICs) setting where RSV interventions remain limited. More efforts should focus on adapting RSV models to LMIC data to project the impact of upcoming medical interventions for this disease.

Why has the epidemiology of RSV changed during the COVID-19 pandemic?

The coronavirus disease 2019 (COVID-19) pandemic has drastically perturbed the epidemiology of Respiratory Syncytial Virus (RSV) respiratory tract infections in children. The reasons for this are not clear. In this article, we review the current literature and critically discuss the different theories to explain why the epidemiology of RSV has changed during the COVID-19 pandemic. Proposed mechanisms include decreased viral immunity in vulnerable age groups caused by the prolonged lack of RSV circulation early in the pandemic, potential Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2)-induced immune dysregulation, viral interactions between SARS-CoV-2 and RSV, and modifications in health-seeking behaviors as well as heath systems factors. Research in viral genomics and phylogeny, and more robust immunology research is needed to guide RSV prevention and health care resource planning.

Predicted effectiveness of vaccines and extended half-life monoclonal antibodies against RSV hospitalizations in children

Several vaccines and extended half-life monoclonal antibodies (mAbs) against respiratory syncytial virus (RSV) have shown promise in clinical trials. We used age-structured transmission models to predict the possible impact of various RSV prevention strategies including maternal immunization, live-attenuated vaccines, and long-lasting mAbs. Our results suggest that maternal immunization and long-lasting mAbs are likely to be highly effective in preventing RSV hospitalizations in infants under 6 months of age, averting more than half of RSV hospitalizations in neonates. Live-attenuated vaccines could reduce RSV hospitalizations in vaccinated age groups and are also predicted to have a modest effect in unvaccinated age groups because of disruptions to transmission. Compared to year-round vaccination, a seasonal vaccination program at the country level provides at most a minor advantage regarding efficiency. Our findings highlight the substantial public health impact that upcoming RSV prevention strategies may provide.

Assessing the Clinical and Socioeconomic Burden of Respiratory Syncytial Virus in Children Aged Under 5 Years in Primary Care: Protocol for a Prospective Cohort Study in England and Report on the Adaptations of the Study to the COVID-19 Pandemic

Background

Respiratory syncytial virus (RSV) commonly causes lower respiratory tract infections and hospitalization in children. In 2019-2020, the Europe-wide RSV ComNet standardized study protocol was developed to measure the clinical and socioeconomic disease burden of RSV infections among children aged <5 years in primary care. RSV has a recognized seasonality in England.

Objective

We aimed to describe (1) the adaptations of the RSV ComNet standardized study protocol for England and (2) the challenges of conducting the study during the COVID-19 pandemic.

Methods

This study was conducted by the Oxford-Royal College of General Practitioners Research and Surveillance Centre—the English national primary care sentinel network. We invited all (N=248) general practices within the network that undertook virology sampling to participate in the study by recruiting eligible patients (registered population: n=3,056,583). Children aged <5 years with the following case definition of RSV infection were included in the study: those consulting a health care practitioner in primary care with symptoms meeting the World Health Organization’s definition of acute respiratory illness or influenza-like illness who have laboratory-confirmed RSV infection. The parents/guardians of these cases were asked to complete 2 previously validated questionnaires (14 and 30 days postsampling). A sample size of at least 100 RSV-positive cases is required to estimate the percentage of children that consult in primary care who need hospitalization. Assuming a swab positivity rate of 20% in children aged <5 years, we estimated that 500 swabs are required. We adapted our method for the pandemic by extending sampling planned for winter 2020-2021 to a rolling data collection, allowing verbal consent and introducing home swabbing because of increased web-based consultations during the COVID-19 pandemic.

Results

The preliminary results of the data collection between International Organization for Standardization (ISO) weeks 1-41 in 2021 are described. There was no RSV detected in the winter of 2020-2021 through the study. The first positive RSV swab collected through the sentinel network in England was collected in ISO week 17 and then every week since ISO week 25. In total, 16 (N=248, 6.5%) of the virology-sampling practices volunteered to participate; these were high-sampling practices collecting the majority of eligible swabs across the sentinel network—200 (43.8%) out of 457 swabs, of which 54 (N=200, 27%) were positive for RSV.

Conclusions

Measures to control the COVID-19 pandemic meant there was no circulating RSV last winter; however, RSV has circulated out of season, as detected by the sentinel network. The sentinel network practices have collected 40% (200/500) of the required samples, and 27% (54/200) were RSV positive. We have demonstrated the feasibility of implementing a European-standardized RSV disease burden study protocol in England during a pandemic, and we now need to recruit to this adapted protocol.

International Registered Report Identifier (IRRID)

DERR1-10.2196/38026

Seasonality of influenza and coseasonality with avian influenza in Bangladesh, 2010-19: a retrospective, time-series analysis

BACKGROUND

Seasonal and avian influenza viruses circulate among human and poultry populations in Bangladesh. However, the epidemiology of influenza is not well defined in this setting. We aimed to characterise influenza seasonality, examine regional heterogeneity in transmission, and evaluate coseasonality between circulating influenza viruses in Bangladesh.

METHODS

In this retrospective, time-series study, we used data collected between January, 2010, and December, 2019, from 32 hospital-based influenza surveillance sites across Bangladesh. We estimated influenza peak timing and intensity in ten regions using negative binomial harmonic regression models, and applied meta-analytic methods to determine whether seasonality differed across regions. Using live bird market surveillance data in Dhaka, Bangladesh, we estimated avian influenza seasonality and examined coseasonality between human and avian influenza viruses.

FINDINGS

Over the 10-year study period, we included 8790 human influenza cases and identified a distinct influenza season, with an annual peak in June to July each year (peak calendar week 27·6, 95% CI 26·7-28·6). Epidemic timing varied by region (I2=93·9%; p<0·0001), with metropolitan regions peaking earlier and epidemic spread following a spatial diffusion pattern based on geographical proximity. Comparatively, avian influenza displayed weak seasonality, with moderate year-round transmission and a small peak in April (peak calendar week 14·9, 95% CI 13·2-17·0), which was out of phase with influenza peaks in humans.

INTERPRETATION

In Bangladesh, influenza prevention and control activities could be timed with annual seasonality, and regional heterogeneity should be considered in health resource planning. Year-round avian influenza transmission poses a risk for viral spillover, and targeted efforts will be crucial for mitigating potential reassortment and future pandemic threats.

FUNDING

Canadian Institute of Health Research Vanier Canada Graduate Scholarship.

Relative timing of respiratory syncytial virus epidemics in summer 2021 across the United States was similar to a typical winter season

We used a validated proxy of respiratory syncytial virus (RSV) activity in the United States (Google search data) to evaluate the onsets of RSV epidemics in 2021 and 2016-2019. Despite the unusual out-of-season summer timing, the relative timing of RSV epidemics between states in 2021 shared a similar spatial pattern with typical winter RSV seasons. Our results suggest that the onset of RSV epidemics in Florida can serve as a baseline to adjust the initiation of prophylaxis administration and clinical trials in other states regardless of the seasonality of RSV epidemics.

Challenges in Maximizing Impacts of Preventive Strategies against Respiratory Syncytial Virus (RSV) Disease in Young Children

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract illness in infants and young children. It causes substantial morbidity and mortality in young children and older adults. As few therapeutic and prophylaxis options against RSV illness are currently available, there is a great need for effective RSV vaccines and immune-prophylaxis. Encouragingly, multiple vaccines and immuno-prophylaxis aiming to protect pediatric populations have shown promising progress in clinical trials. The three major preventive strategies include RSV F-protein-based vaccines for pregnant women, extended half-life monoclonal antibodies for neonates, and live-attenuated vaccines for infants. Each preventive strategy has its own merits and challenges yet to be overcome. Challenges also exist in maximizing vaccine impacts in the post-implementation era. This perspectives piece focuses on RSV preventive strategies in young children and highlights the remaining questions in current development of RSV immunization products and design of immunization programs.

The impact of COVID-19 non-pharmaceutical interventions on future respiratory syncytial virus transmission in South Africa

In response to the COVID-19 pandemic, the South African government employed various nonpharmaceutical interventions (NPIs) in order to reduce the spread of SARS-CoV-2. In addition to mitigating transmission of SARS-CoV-2, these public health measures have also functioned in slowing the spread of other endemic respiratory pathogens. Surveillance data from South Africa indicates low circulation of respiratory syncytial virus (RSV) throughout the 2020-2021 Southern Hemisphere winter seasons. Here we fit age-structured epidemiological models to national surveillance data to predict the 2022 RSV outbreak following two suppressed seasons. We project a 32% increase in the peak number of monthly hospitalizations among infants ≤ 2 years, with older infants (6-23 month olds) experiencing a larger portion of severe disease burden than typical. Our results suggest that hospital system readiness should be prepared for an intense RSV season in early 2022.

Increasing concentration of COVID-19 by socioeconomic determinants and geography in Toronto, Canada: an observational study

BACKGROUND

Inequities in the burden of COVID-19 were observed early in Canada and around the world, suggesting economically marginalized communities faced disproportionate risks. However, there has been limited systematic assessment of how heterogeneity in risks has evolved in large urban centers over time.

PURPOSE

To address this gap, we quantified the magnitude of risk heterogeneity in Toronto, Ontario from January to November 2020 using a retrospective, population-based observational study using surveillance data.

METHODS

We generated epidemic curves by social determinants of health (SDOH) and crude Lorenz curves by neighbourhoods to visualize inequities in the distribution of COVID-19 and estimated Gini coefficients. We examined the correlation between SDOH using Pearson-correlation coefficients.

RESULTS

Gini coefficient of cumulative cases by population size was 0.41 (95% confidence interval [CI]:0.36-0.47) and estimated for: household income (0.20, 95%CI: 0.14-0.28); visible minority (0.21, 95%CI:0.16-0.28); recent immigration (0.12, 95%CI:0.09-0.16); suitable housing (0.21, 95%CI:0.14-0.30); multigenerational households (0.19, 95%CI:0.15-0.23); and essential workers (0.28, 95%CI:0.23-0.34).

CONCLUSIONS

There was rapid epidemiologic transition from higher- to lower-income neighborhoods with Lorenz curve transitioning from below to above the line of equality across SDOH. Moving forward necessitates integrating programs and policies addressing socioeconomic inequities and structural racism into COVID-19 prevention and vaccination programs.

Increasing concentration of COVID-19 by socioeconomic determinants and geography in Toronto, Canada: an observational study

BACKGROUND

Inequities in the burden of COVID-19 were observed early in Canada and around the world suggesting economically marginalized communities faced disproportionate risks. However, there has been limited systematic assessment of how heterogeneity in risks has evolved in large urban centers over time.

PURPOSE

To address this gap, we quantified the magnitude of risk heterogeneity in Toronto, Ontario from January-November, 2020 using a retrospective, population-based observational study using surveillance data.

METHODS

We generated epidemic curves by social determinants of health (SDOH) and crude Lorenz curves by neighbourhoods to visualize inequities in the distribution of COVID-19 and estimated Gini coefficients. We examined the correlation between SDOH using Pearson-correlation coefficients.

RESULTS

Gini coefficient of cumulative cases by population size was 0.41 (95% confidence interval [CI]:0.36-0.47) and estimated for: household income (0.20, 95%CI: 0.14-0.28); visible minority (0.21, 95%CI:0.16-0.28); recent immigration (0.12, 95%CI:0.09-0.16); suitable housing (0.21, 95%CI:0.14-0.30); multi-generational households (0.19, 95%CI:0.15-0.23); and essential workers (0.28, 95%CI:0.23-0.34).

CONCLUSIONS

There was rapid epidemiologic transition from higher to lower income neighbourhoods with Lorenz curve transitioning from below to above the line of equality across SDOH. Moving forward necessitates integrating programs and policies addressing socioeconomic inequities and structural racism into COVID-19 prevention and vaccination programs.