Publications by authors named "Kathy Leung"

The Immunization and Vaccines-related Implementation Research Advisory Committee (IVIR-AC) is the primary advisory body of the World Health Organization conducting independent reviews of immunization-related implementation research, with a primary focus on transmission and economic modeling analyses that estimate the value and impact of vaccines. From 10 to 13th September 2024, IVIR-AC convened virtually for its second of two semi-annual meetings to provide feedback and recommendations across six sessions including: pneumococcal vaccination strategies that rely on indirect protection; vaccine impact modeling for chikungunya; The Lancet Commission on strengthening the use of epidemiological modeling of emerging and pandemic infectious diseases; methods for immunization coverage estimation; setting immunization research priorities in the South-East Asian Region; and modeling evidence related to typhoid conjugate vaccine schedules. This report summarizes the sessions, proceedings, and recommendations from that meeting.

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Objectives: This study aimed to assess the long-term persistence of neutralizing antibodies (nAb) titres and seroprotection proportions after the fourth and fifth doses of inactivated polio vaccine (IPV).

Methods: Serum samples from 299 children in Hong Kong were collected and used to estimate the persistence of nAb titres and seroprotection proportions by neutralisation test.

Results: The mean nAb titres against poliovirus types 1, 2, and 3 (PV1, PV2, and PV3) 1 month after receiving the fourth dose of IPV at 19 months of age were 2068 (95% credible interval, 1517-2864); 4705 (3439-6436); and 2758 (1894-4086); respectively, but declined substantially in 4 years to 268 (222-325), 751 (630-900), and 411 (323-521), respectively.

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The World Health Organization's Immunization and Vaccines-related Implementation Research Advisory Committee (IVIR-AC) serves to independently review and evaluate vaccine-related research to maximize the potential impact of vaccination programs. From 28 June - 1 July 2024, IVIR-AC was convened for an ad hoc meeting to discuss new evidence on criteria for rubella vaccine introduction and the risk of congenital rubella syndrome. This report summarizes background information on rubella virus transmission and the burden of congenital rubella syndrome, meeting structure and presentations, proceedings, and recommendations.

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Open source, lightweight and offline generative large language models (LLMs) hold promise for clinical information extraction due to their suitability to operate in secured environments using commodity hardware without token cost. By creating a simple lupus nephritis (LN) renal histopathology annotation schema and generating gold standard data, this study investigates prompt-based strategies using three state-of-the-art lightweight LLMs, namely BioMistral-DARE-7B (BioMistral), Llama-2-13B (Llama 2), and Mistral-7B-instruct-v0.2 (Mistral).

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Background: COVID-19 protective behaviors are key interventions advised by the World Health Organization (WHO) to prevent COVID-19 transmission. However, achieving compliance with this advice is often challenging, particularly among socially vulnerable groups.

Objective: We developed a social vulnerability index (SVI) to predict individuals' propensity to adhere to the WHO advice on protective behaviors against COVID-19 and identify changes in social vulnerability as Omicron evolved in African countries between January 2022 and August 2022 and Asia Pacific countries between August 2021 and June 2022.

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The Immunization and Vaccine-related Implementation Research Advisory Committee (IVIR-AC) is the World Health Organization's key standing advisory body to conduct an independent review of research, particularly of transmission and economic modeling analyses that estimate the impact and value of vaccines. From 26th February-1st March 2024, at its first of two semi-annual meetings, IVIR-AC provided feedback and recommendations across four sessions; this report summarizes the proceedings and recommendations from that meeting. Session topics included modeling of the impact and cost-effectiveness of the R21/Matrix-M malaria vaccine, meta-analysis of economic evaluations of vaccines, a global analysis estimating the impact of vaccination over the last 50 years, and modeling the impact of different RTS,S malaria vaccine dose schedules in seasonal settings.

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The wastewater surveillance network successfully established for COVID-19 showed great potential to monitor other infectious viruses, such as norovirus, rotavirus and mpox virus. In this study, we established and validated detection methods for these viruses in wastewater. We developed a supernatant-based method to detect RNA viruses from wastewater samples and applied it to the monthly diarrhea viruses (norovirus genogroup I & II, and rotavirus) surveillance in wastewater treatment plants (WWTPs) at a city-wide level for 16 months.

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Introduction: Type 2 diabetes is preventable in subjects with impaired glucose tolerance based on 2-hour plasma glucose (2hPG) during 75 g oral glucose tolerance test (OGTT). We incorporated routine biochemistry to improve the performance of a non-invasive diabetes risk score to identify individuals with abnormal glucose tolerance (AGT) defined by 2hPG≥7.8 mmol/L during OGTT.

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Background: Novel coronaviruses have emerged and caused major epidemics and pandemics in the past 2 decades, including SARS-CoV-1, MERS-CoV, and SARS-CoV-2, which led to the current COVID-19 pandemic. These coronaviruses are marked by their potential to produce disproportionally large transmission clusters from superspreading events (SSEs). As prompt action is crucial to contain and mitigate SSEs, real-time epidemic size estimation could characterize the transmission heterogeneity and inform timely implementation of control measures.

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Article Synopsis
  • A study found that 96.8% of healthy adults in Hong Kong had strong antibodies against the influenza A(H5N1) virus in 2020, compared to just 42% in 2009.
  • The high levels of antibodies indicate a significant immune response to this specific virus strain among the population.
  • Additionally, a correlation was observed between the antibody levels for influenza A(H1N1)pdm09 and A(H5N1), suggesting a potential relationship in immune responses to these viruses.
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The quality of carbohydrates has metabolic consequences in people with prediabetes. However, the causality of short-chain fermentable carbohydrate intakes and metabolic parameters has not been explored in the prediabetic or diabetic population. We investigated associations between different types of carbohydrates, including fermentable oligosaccharides, disaccharides, monosaccharides, polyols (FODMAPs), and polysaccharides (dietary fibre), and body composition and glucose/insulin responses in subjects with prediabetes.

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Background: Natural SARS-CoV-2 infection may elicit antibodies to a range of viral proteins including non-structural protein ORF8. RNA, adenovirus vectored and sub-unit vaccines expressing SARS-CoV-2 spike would be only expected to elicit S-antibodies and antibodies to distinct domains of nucleocapsid (N) protein may reliably differentiate infection from vaccine-elicited antibody. However, inactivated whole virus vaccines may potentially elicit antibody to wider range of viral proteins, including N protein.

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Objective: China has a substantial disease burden of cervical cancer. To further understand preventive measures for reducing cervical cancer in China, this study aimed to correlate screening attendance and regular screening with human papillomavirus (HPV) vaccination among Chinese females.

Methods: This prospective questionnaire-based survey recruited Chinese females aged 25 or above in Hong Kong by random digit dialing telephone interviews in 2022.

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Importance: Hong Kong was held as an exemplar for pandemic response until it recorded the world's highest daily COVID-19 mortality, which was likely due to vaccine refusal. To prevent this high mortality in future pandemics, information on underlying reasons for vaccine refusal is necessary.

Objectives: To track the evolution of COVID-19 vaccination willingness and uptake from before vaccine rollout to mass vaccination, to examine factors associated with COVID-19 vaccine refusal and compare with data from Singapore, and to assess the population attributable fraction for vaccine refusal.

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Wastewater surveillance is considered as a powerful tool in providing cost-effective, population-wide and near real-time surveillance results for controlling infectious diseases (i.e., SARS-CoV-2, influenza virus), complementary to clinical surveillance.

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Humans display substantial interindividual clinical variability after SARS-CoV-2 infection, the genetic and immunological basis of which has begun to be deciphered. However, the extent and drivers of population differences in immune responses to SARS-CoV-2 remain unclear. Here we report single-cell RNA-sequencing data for peripheral blood mononuclear cells-from 222 healthy donors of diverse ancestries-that were stimulated with SARS-CoV-2 or influenza A virus.

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Chatbots have become an increasingly popular tool in the field of health services and communications. Despite chatbots' significance amid the COVID-19 pandemic, few studies have performed a rigorous evaluation of the effectiveness of chatbots in improving vaccine confidence and acceptance. In Thailand, Hong Kong, and Singapore, from February 11th to June 30th, 2022, we conducted multisite randomised controlled trials (RCT) on 2,045 adult guardians of children and seniors who were unvaccinated or had delayed vaccinations.

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Introduction: Obesity and diabetes are public health concerns worldwide, but few studies have examined the habitual intake of minerals on body composition in people with prediabetes.

Methods: In this prospective cross-sectional study, 155 Chinese subjects with IGT [median age: 59 (53-62) years, 58% female] had an assessment of body composition including body fat percentage, oral glucose tolerance tests (OGTT), Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and 3-day food records from nutritional programme analysis.

Results: Dietary intake of minerals was negatively correlated with body fat.

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Hong Kong experienced a surge of Omicron BA.2 infections in early 2022, resulting in one of the highest per-capita death rates of COVID-19. The outbreak occurred in a dense population with low immunity towards natural SARS-CoV-2 infection, high vaccine hesitancy in vulnerable populations, comprehensive disease surveillance and the capacity for stringent public health and social measures (PHSMs).

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Background: Few studies have examined the temporal trends of Helicobacter pylori prevalence worldwide. We aimed to identify the changes in global prevalence of H pylori infection between 1980 and 2022.

Methods: In this systematic review and meta-analysis, we searched PubMed, Embase, MEDLINE, Scopus, and Web of Science, with no language restrictions, for observational studies on the prevalence of H pylori infection published between Jan 1, 1980, and Dec 31, 2022.

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