The city-wide full-scale interactive application of sewage surveillance programme for assisting real-time COVID-19 pandemic control - A case study in Hong Kong.

The paper discusses the implementation of Hong Kong's tailor-made sewage surveillance programme led by the Government, which has demonstrated how an efficient and well-organized sewage surveillance system can complement conventional epidemiological surveillance to facilitate the planning of intervention strategies and actions for combating COVID-19 pandemic in real-time. This included the setting up of a comprehensive sewerage network-based SARS-CoV-2 virus surveillance programme with 154 stationary sites covering 6 million people (or 80 % of the total population), and employing an intensive monitoring programme to take samples from each stationary site every 2 days. From 1 January to 22 May 2022, the daily confirmed case count started with 17 cases per day on 1 January to a maximum of 76,991 cases on 3 March and dropped to 237 cases on 22 May. During this period, a total of 270 "Restriction-Testing Declaration" (RTD) operations at high-risk residential areas were conducted based on the sewage virus testing results, where over 26,500 confirmed cases were detected with a majority being asymptomatic. In addition, Compulsory Testing Notices (CTN) were issued to residents, and the distribution of Rapid Antigen Test kits was adopted as alternatives to RTD operations in areas of moderate risk. These measures formulated a tiered and cost-effective approach to combat the disease in the local setting. Some ongoing and future enhancement efforts to improve efficacy are discussed from the perspective of wastewater-based epidemiology. Forecast models on case counts based on sewage virus testing results were also developed with R2 of 0.9669-0.9775, which estimated that up to 22 May 2022, around 2,000,000 people (~67 % higher than the total number of 1,200,000 reported to the health authority, due to various constraints or limitations) had potentially contracted the disease, which is believed to be reflecting the real situation occurring in a highly urbanized metropolis like Hong Kong.

High prevalence of extended-spectrum beta-lactamase organisms and the COVID-19 pandemic impact on donor recruitment for fecal microbiota transplantation in Hong Kong.

BACKGROUND: With increasing number of clinical trials relating to fecal microbiota transplantation (FMT), it is crucial to identify and recruit long-term, healthy, and regular fecal donors. OBJECTIVE: We aimed to report the outcomes of screening and recruitment of fecal donors for FMT. METHODS: Potential donors were recruited via advertisement through internal mass emails at a university. They were required to undergo a pre-screening telephone interview, a detailed questionnaire, followed by blood and stool investigations. RESULTS: From January 2017 to December 2020, 119 potential donors were assessed with 75 failed pre-screening. Reasons for failure included: inability to come back for regular and long-term donation (n = 19), high body mass index (n = 17), underlying chronic illness or on long-term medications (n = 11), being healthcare professionals (n = 10), use of antibiotics within 3 months (n = 5) and others (n = 13). Forty-four donors completed questionnaires and 11 did not fulfill the clinical criteria. Of the remaining 33 potential donors who had stool and blood tests, 21 failed stool investigations (19 extended-spectrum beta-lactamase [ESBL] organisms, one Clostridioides difficile, one C. difficile plus Methicillin Resistant Staphylococcus aureus), one failed blood tests (high serum alkaline phosphatase level), one required long-term medication and nine withdrew consent and/or lost to follow-up. In total, only one out of 119 (0.8%) potential donors was successfully recruited as a regular donor. CONCLUSION: There was a high failure rate in donor screening for FMT. Main reasons for screening failure included high prevalence of positive ESBL organisms in stool and failed commitment to regular stool donation.

A modeling investigation of the impact of street and building configurations on personal air pollutant exposure in isolated deep urban canyons.

This study evaluated the effectiveness of different configurations for two building design elements, namely building permeability and setback, proposed for mitigating air pollutant exposure problems in isolated deep canyons by using an indirect exposure approach. The indirect approach predicted the exposures of three different population subgroups (i.e. pedestrians, shop vendors and residents) by multiplying the pollutant concentrations with the duration of exposure within a specific micro-environment. In this study, the pollutant concentrations for different configurations were predicted using a computational fluid dynamics model. The model was constructed based on the Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-ε turbulence model. Fifty-one canyon configurations with aspect ratios of 2, 4, 6 and different building permeability values (ratio of building spacing to the building façade length) or different types of building setback (recess of a high building from the road) were examined. The findings indicated that personal exposures of shop vendors were extremely high if they were present inside a canyon without any setback or separation between buildings and when the prevailing wind was perpendicular to the canyon axis. Building separation and building setbacks were effective in reducing personal air exposures in canyons with perpendicular wind, although their effectiveness varied with different configurations. Increasing the permeability value from 0 to 10% significantly lowered the personal exposures on the different population subgroups. Likewise, the personal exposures could also be reduced by the introduction of building setbacks despite their effects being strongly influenced by the aspect ratio of a canyon. Equivalent findings were observed if the reduction in the total development floor area (the total floor area permitted to be developed within a particular site area) was also considered. These findings were employed to formulate a hierarchy decision making model to guide the planning of deep canyons in high density urban cities.

Study of the PM10 concentration variations along two intra-urban roads within a compact city.

Eighty-five measurement campaigns were performed repeatedly to compare the concentration variation profiles along two intra-urban roads-one with open configuration and the other with street canyon effect. Fixed-effects panel data analysis was applied for formulating a model to express the PM(10) concentrations along intra-urban roads in terms of parameters like nearby central monitoring data, traffic counts and meteorological conditions with an objective to analyze the PM(10) concentration variation patterns along the two roads. Our findings reveal that traffic intensity and metrological conditions exert influence on concentration variation for both types of road configurations while wind velocity only affect the pollutants removal effectiveness of open road configuration. Further analysis unveils that the PM(10) concentration distribution profiles within a compact city environment are not always uniform and are dependent on the road configuration. Considerable PM(10) concentration differences were observed along the street canyon, and 70% of their variations are attributed to variations in their road aspect ratios. By contrast, no significant concentration difference is observed at open road configurations.