Exploring how socioeconomic status affects neighbourhood environments? : effects on obesity risks : a longitudinal study in Singapore

Research on how socioeconomic status interacts with neighbourhood characteristics to influence disparities in obesity outcomes is currently limited by residential segregation-induced structural confounding, a lack of empirical studies outside the U.S. and other 'Western' contexts, and an over-reliance on cross-sectional analyses. This study addresses these challenges by examining how socioeconomic status modifies the effect of accumulated exposures to obesogenic neighbourhood environments on children and mothers' BMI, drawing from a longitudinal mother-child birth cohort study in Singapore, an Asian city-state with relatively little residential segregation. We find that increased access to park connectors was associated with a decrease in BMI outcomes for mothers with higher socioeconomic status, but an increase for those with lower socioeconomic status. We also find that increased access to bus stops was associated with an increase in BMIz of children with lower socioeconomic status, but with a decrease in BMIz of children with higher socioeconomic status, while increased access to rail stations was associated with a decrease in BMIz of children with lower socioeconomic status only. Our results suggest that urban interventions might have heterogeneous effects by socioeconomic status.Peer reviewe

Modelling lockdown and exit strategies for COVID-19 in Singapore.

BACKGROUND: With at least 94 countries undergoing or exiting lockdowns for contact suppression to control the COVID-19 outbreak, sustainable and public health-driven exit strategies are required. Here we explore the impact of lockdown and exit strategies in Singapore for immediate planning. METHODS: We use an agent-based model to examine the impacts of epidemic control over 480 days. A limited control baseline of case isolation and household member quarantining is used. We measure the impact of lockdown duration and start date on final infection attack sizes. We then apply a 3-month gradual exit strategy, immediately re-opening schools and easing workplace distancing measures, and compare this to long-term social distancing measures. FINDINGS: At baseline, we estimated 815 400 total infections (21.6% of the population). Early lockdown at 5 weeks with no exit strategy averted 18 500 (2.27% of baseline averted), 21 300 (2.61%) and 22 400 (2.75%) infections for 6, 8 and 9-week lockdown durations. Using the exit strategy averted a corresponding 114 700, 121 700 and 126 000 total cases, representing 12.07-13.06% of the total epidemic size under baseline. This diminishes to 9 900-11 300 for a late 8-week start time. Long-term social distancing at 6 and 8-week durations are viable but less effective. INTERPRETATION: Gradual release exit strategies are critical to maintain epidemic suppression under a new normal. We present final infection attack sizes assuming the ongoing importation of cases, which require preparation for a potential second epidemic wave due to ongoing epidemics elsewhere. FUNDING: Singapore Ministry of Health, Singapore Population Health Improvement Centre

Effects of marking methods and fluorescent dusts on Aedes aegypti survival

BACKGROUND: Tracking the movement of mosquitoes and understanding dispersal dynamics is essential for the control and prevention of vector-borne diseases. A variety of marking techniques have been used, including dusts and dyes. METHODS: In this study, Aedes aegypti were marked using fluorescent dusts (‘DayGlo’: A-19 Horizon Blue & A-13-N Rocket Red; ‘Brian Clegg’: pink, blue & red), fluorescent paints (‘Brian Clegg’: blue, red & yellow) and metallic gold dust (‘Brian Clegg’). Dusting methods were those previously used in mark-release-recapture experiments, including application with a bulb duster, creation of a dust storm or shaking in a bag. RESULTS: Results showed marking mosquitoes using a dust storm allowed relatively high survival, compared to unmarked controls (Males: χ(2) = 3.24, df = 4, p = 0.07; Females: χ(2) = 3.24, df = 4, p = 0.04), and high marking efficiency. Using a bulb duster showed high survival in male mosquitoes (χ(2) = 12.59, df = 4, p < 0.000), but low survival in female mosquitoes during the first 15 days of the study (χ(2) = 5.17, df = 4, p < 0.05). The bulb duster also had the lowest marking efficiency compared to other dry marking techniques. The bag method showed low survival in males during the first 15 days of the study (χ(2) = 5.77, df = 4, p < 0.05). Applying paints had an overall negative impact on survival for males (χ(2) = 5.03, df = 3, p < 0.05), but not for females (χ(2) = 0.19, df = 3, p = 0.661). Males dusted with DayGlo Horizon Blue dust, and females dusted with DayGlo Rocket Red dust, had the most significant reduction in survivorship in comparison to the control (Males: χ(2) = 15.70, df = 6, p < 0.000; Females: χ(2) = 24.47, df = 6, p < 0.000). Mosquitoes marked with Brian Clegg gold dust showed mortality rates similar to controls within male mosquitoes (χ(2) = 0.18, df = 6, p = 0.674), but significantly lower in females (χ(2) = 16.59, df = 6, p < 0.000). CONCLUSIONS: This study showed that marking technique and colour can have a significant impact on the survival and marking coverage of a mosquito

Institutional versus home isolation to curb the COVID-19 outbreak reply

10.1016/S0140-6736(20)32171-1LANCET396102631632-163

Time to Empower Release of Insects Carrying a Dominant Lethal and Wolbachia Against Zika

10.1093/ofid/ofw103OPEN FORUM INFECTIOUS DISEASES3

Mapping the cryptic spread of the 2015–2016 global Zika virus epidemic

Supplementary data for paper titled "Mapping the cryptic spread of the 2015–2016 global Zika virus epidemic". Research outputs include a tabular dataset that contains a weekly number of reported autochthonous Zika cases by each country or subdivision during 2015–2016 (Additional file 2), R code (Additional file 3) a tabular dataset which contains reported and simulated total number of Zika cases (additional file 6), a tabular dataset that contains estimated probability of no onward spread of ZIKV occurred following importation during 2015–2016 (additional file 7), and a tabular dataset that lists first-level country subdivisions belonging to each susceptible spatial unit (additional file 8). All files are hosted on Figshare

Forecasting upper respiratory tract infection burden using high-dimensional time series data and forecast combinations

Upper respiratory tract infections (URTIs) represent a large strain on primary health resources. To mitigate URTI transmission and public health burdens, it is important to pre-empt and provide forward guidance on URTI burden, while taking into account various facets which influence URTI transmission. This is so that appropriate public health measures can be taken to mitigate strain on primary care resources. This study describes a new approach to forecasting URTIs which can be used for national public health resource planning. Specifically, using environmental and disease data comprising more than 1000 dimensions, we developed sub-models which optimizes model explainability, in-sample model fit, predictive accuracy and combines many weaker predictors over a 2-month time horizon to generate direct, point forecasts over a 1-8 week ahead forecast horizon. Predictive performance was evaluated using rolling out-of-sample forecast assessment within both periods with/without structural breaks in transmission over the period of 2012-2022. We showed that forecast combinations of 5 other forecasting models had better and more consistent predictive performance than other modelling approaches, over periods with and without structural breaks in transmission dynamics. Furthermore, epidemiological analysis on high dimensional data was enabled using post-selection inference, to show the dynamic association between lower temperature, increases in past relative humidity and absolute humidity and increased URTIs attendance. The methods proposed can be used for outbreak preparedness and guide healthcare resource planning, in both stable periods of transmission and periods where structural breaks in data occur.Ministry of Education (MOE)Nanyang Technological UniversityPublished versionThis research project is supported by the Lee Kong Chian School of Medicine - Ministry of Education Start-Up Grant

Institutional, not home-based, isolation could contain the COVID-19 outbreak

10.1016/S0140-6736(20)31016-3LANCET395102361541-154

Urban-Rural Disparities for COVID-19: Evidence from 10 Countries and Areas in the Western Pacific.

BACKGROUND: Limited evidence on the effectiveness of various types of social distancing measures, from voluntary physical distancing to a community-wide quarantine, exists for the Western Pacific Region (WPR) which has large urban and rural populations. METHODS: We estimated the time-varying reproduction number (R t ) in a Bayesian framework using district-level mobility data provided by Facebook (i) to assess how various social distancing policies have contributed to the reduction in transmissibility of SARS-COV-2 and (ii) to examine within-country variations in behavioural responses, quantified by reductions in mobility, for urban and rural areas. RESULTS: Social distancing measures were largely effective in reducing transmissibility, with R t estimates decreased to around the threshold of 1. Within-country analysis showed substantial variation in public compliance across regions. Reductions in mobility were significantly lower in rural and remote areas than in urban areas and metropolitan cities (p < 0.001) which had the same scale of social distancing orders in place. CONCLUSIONS: Our findings provide empirical evidence that public compliance and consequent intervention effectiveness differ between urban and rural areas in the WPR. Further work is required to ascertain the factors affecting these differing behavioural responses, which can assist in policy-making efforts and increase public compliance in rural areas where populations are older and have poorer access to healthcare

A Systematic Review of COVID-19 Epidemiology Based on Current Evidence.

10.3390/jcm9040967J Clin Med94967-96