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347 results on '"Tsang, Tim K."'

1. Influenza Resurgence after Relaxation of Public Health and Social Measures, Hong Kong, 2023

Author

Xiong, Weijia, Cowling, Benjamin J., and Tsang, Tim K.

Subjects
Infection control -- Laws, regulations and rules, Epidemics -- Statistics -- Control -- Causes of -- Hong Kong, Influenza -- Statistics -- Control -- Causes of, Disease transmission -- Research, Virus research, Government regulation, Health
Abstract

To control COVID-19, Hong Kong, China, put in place several public health and social measures (PHSMs), including mandatory mask wearing, school closures, hand hygiene, and avoidance of gatherings. In early [...]

Published
2023

2. Characterizing human collective behaviours of COVID-19 in Hong Kong

Author

Du, Zhanwei, Zhang, Xiao, Wang, Lin, Yao, Sidan, Bai, Yuan, Tan, Qi, Xu, Xiaoke, Pei, Sen, Xiao, Jingyi, Tsang, Tim K., Liao, Qiuyan, Lau, Eric, Wu, Peng, Gao, Chao, and Cowling, Benjamin J

Subjects
Computer Science - Social and Information Networks, Physics - Physics and Society
Abstract

People are likely to engage in collective behaviour online during extreme events, such as the COVID-19 crisis, to express their awareness, actions and concerns. Hong Kong has implemented stringent public health and social measures (PHSMs) to curb COVID-19 epidemic waves since the first COVID-19 case was confirmed on 22 January 2020. People are likely to engage in collective behaviour online during extreme events, such as the COVID-19 crisis, to express their awareness, actions and concerns. Here, we offer a framework to evaluate interactions among individuals emotions, perception, and online behaviours in Hong Kong during the first two waves (February to June 2020) and found a strong correlation between online behaviours of Google search and the real-time reproduction numbers. To validate the model output of risk perception, we conducted 10 rounds of cross-sectional telephone surveys from February 1 through June 20 in 2020 to quantify risk perception levels over time. Compared with the survey results, the estimates of the risk perception of individuals using our network-based mechanistic model capture 80% of the trend of people risk perception (individuals who worried about being infected) during the studied period. We may need to reinvigorate the public by engaging people as part of the solution to live their lives with reduced risk.

Published
2022

3. Effects of School-Based Preventive Measures on COVID-19 Incidence, Hong Kong, 2022

Author

Tsang, Tim K., Huang, Xiaotong, Fong, Min Whui, Wang, Can, Lau, Eric H.Y., Wu, Peng, and Cowling, Benjamin J.

Subjects
Vaccination -- Health aspects -- Analysis, Infection -- Health aspects -- Analysis, Vaccines -- Health aspects -- Analysis, Health
Abstract

After 2 years of minimal incidence of SARS-CoV-2 infections in Hong Kong, the Omicron BA.2 variant began to spread in January 2022. The resulting 5th COVID-19 wave in Hong Kong's [...]

Published
2023
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5. Resurgence of Omicron BA.2 in SARS-CoV-2 infection-naive Hong Kong

Author

Xie, Ruopeng, Edwards, Kimberly M., Adam, Dillon C., Leung, Kathy S. M., Tsang, Tim K., Gurung, Shreya, Xiong, Weijia, Wei, Xiaoman, Ng, Daisy Y. M., Liu, Gigi Y. Z., Krishnan, Pavithra, Chang, Lydia D. J., Cheng, Samuel M. S., Gu, Haogao, Siu, Gilman K. H., Wu, Joseph T., Leung, Gabriel M., Peiris, Malik, Cowling, Benjamin J., Poon, Leo L. M., and Dhanasekaran, Vijaykrishna

Published
2023
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11. Epidemiology of SARS-CoV-2 Omicron BA.5 Infections, Macau, June-July 2022

Author

Xiong, Weijia, Peng, Liping, Tsang, Tim K., and Cowling, Benjamin J.

Subjects
Epidemics -- Statistics -- Control -- Macao, Health
Abstract

The SARS-CoV-2 Omicron subvariant BA.5 has spread rapidly worldwide. A recent outbreak of BA.5 occurred in Macau during June 18-July 31, 2022. The outbreak resulted in 1,821 confirmed cases and [...]

Published
2023

13. Determining Existing Human Population Immunity as Part of Assessing Influenza Pandemic Risk

Author

Cheung, Jonathan Tin Lai, Tsang, Tim K., Yen, Hui-Ling, Perera, Ranawaka A.P.M., Mok, Chris Ka Pun, Lin, Yong Ping, Cowling, Benjamin J., and Peiris, Malik

Subjects
Epidemics -- Risk factors -- Statistics -- China, Immunological research, Sentinel health events -- Methods, Influenza -- Risk factors -- Statistics, Immunity -- Research, Health
Abstract

An influenza pandemic can occur when an influenza A virus with gene segments derived in part or whole from animal viruses becomes able to efficiently and sustainably transmit among humans [...]

Published
2022
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22. Effects of infection history on dengue virus infection and pathogenicity

Author

Tsang, Tim K, Ghebremariam, Samson L, Gresh, Lionel, Gordon, Aubree, Halloran, M Elizabeth, Katzelnick, Leah C, Rojas, Diana Patricia, Kuan, Guillermina, Balmaseda, Angel, Sugimoto, Jonathan, Harris, Eva, Longini, Ira M, and Yang, Yang

Subjects
Rare Diseases, Pediatric Research Initiative, Immunization, Biotechnology, Prevention, Pediatric, Vaccine Related, Biodefense, Vector-Borne Diseases, Clinical Research, Emerging Infectious Diseases, Infectious Diseases, Aetiology, 2.1 Biological and endogenous factors, Infection, Good Health and Well Being, Adolescent, Age Factors, Antibodies, Viral, Child, Child, Preschool, Cross Reactions, Dengue, Dengue Virus, Female, Host Microbial Interactions, Humans, Male, Nicaragua, Prospective Studies, Risk Factors, Serogroup, Vaccination, Virulence
Abstract

The understanding of immunological interactions among the four dengue virus (DENV) serotypes and their epidemiological implications is often hampered by the lack of individual-level infection history. Using a statistical framework that infers full infection history, we analyze a prospective pediatric cohort in Nicaragua to characterize how infection history modulates the risks of DENV infection and subsequent clinical disease. After controlling for age, one prior infection is associated with 54% lower, while two or more are associated with 91% higher, risk of a new infection, compared to DENV-naive children. Children >8 years old have 55% and 120% higher risks of infection and subsequent disease, respectively, than their younger peers. Among children with ≥1 prior infection, intermediate antibody titers increase, whereas high titers lower, the risk of subsequent infection, compared with undetectable titers. Such complex dependency needs to be considered in the design of dengue vaccines and vaccination strategies.

Published
2019

25. Restaurant-Based Measures to Control Community Transmission of COVID-19, Hong Kong

Author

Ho, Faith, Tsang, Tim K., Gao, Huizhi, Xiao, Jingyi, Lau, Eric H.Y., Wong, Jessica Y., Wu, Peng, Leung, Gabriel M., and Cowling, Benjamin J.

Subjects
Infection control -- Methods, Epidemics -- Social aspects -- Control -- Hong Kong, Restaurant industry -- Health aspects -- Safety and security measures, Health
Abstract

As of April 14, 2021, a total of 11,608 cases and 207 deaths from coronavirus disease (COVID-19) had been reported in Hong Kong (1). A series of community epidemics have [...]

Published
2022
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26. Effectiveness of International Travel Controls for Delaying Local Outbreaks of COVID-19

Author

Yang, Bingyi, Sullivan, Sheena G., Du, Zhanwei, Tsang, Tim K., and Cowling, Benjamin J.

Subjects
Epidemics -- Statistics -- Control -- International aspects, Travel restrictions -- Evaluation -- International aspects, Government regulation, Health
Abstract

International travel control (e.g., screening of inbound travelers, requiring quarantines, and even closing borders) has been a key strategy implemented by many countries to limit importations of severe acute respiratory [...]

Published
2022

30. Clustering and superspreading potential of SARS-CoV-2 infections in Hong Kong

Author

Adam, Dillon C., Wu, Peng, Wong, Jessica Y., Lau, Eric H. Y., Tsang, Tim K., Cauchemez, Simon, and Leung, Gabriel M.

Subjects
Disease transmission -- History -- Distribution, Company distribution practices, Biological sciences, Health
Abstract

Superspreading events (SSEs) have characterized previous epidemics of severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) infections.sup.1-6. For SARS-CoV-2, the degree to which SSEs are involved in transmission remains unclear, but there is growing evidence that SSEs might be a typical feature of COVID-19.sup.7,8. Using contact tracing data from 1,038 SARS-CoV-2 cases confirmed between 23 January and 28 April 2020 in Hong Kong, we identified and characterized all local clusters of infection. We identified 4-7 SSEs across 51 clusters (n = 309 cases) and estimated that 19% (95% confidence interval, 15-24%) of cases seeded 80% of all local transmission. Transmission in social settings was associated with more secondary cases than households when controlling for age (P = 0.002). Decreasing the delay between symptom onset and case confirmation did not result in fewer secondary cases (P = 0.98), although the odds that an individual being quarantined as a contact interrupted transmission was 14.4 (95% CI, 1.9-107.2). Public health authorities should focus on rapidly tracing and quarantining contacts, along with implementing restrictions targeting social settings to reduce the risk of SSEs and suppress SARS-CoV-2 transmission. Cases linked to superspreading events are estimated to account for 80% of all local transmission of SARS-CoV-2 in Hong Kong in a study with implications for public health policies., Author(s): Dillon C. Adam [sup.1] [sup.2] , Peng Wu [sup.1] , Jessica Y. Wong [sup.1] , Eric H. Y. Lau [sup.1] , Tim K. Tsang [sup.1] , Simon Cauchemez [sup.3] [...]

Published
2020
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31. COVID-19 Vaccination Willingness and Reasons for Vaccine Refusal

Author

Lun, Phyllis, primary, Ning, Ke, additional, Wang, Yishan, additional, Ma, Tiffany S. W., additional, Flores, Francis P., additional, Xiao, Xiao, additional, Subramaniam, Mythily, additional, Abdin, Edimansyah, additional, Tian, Linwei, additional, Tsang, Tim K., additional, Leung, Kathy, additional, Wu, Joseph T., additional, Cowling, Benjamin J., additional, Leung, Gabriel M., additional, and Ni, Michael Y., additional

Published
2023
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34. Risk for International Importations of Variant SARS-CoV-2 Originating in the United Kingdom

Author

Du, Zhanwei, Wang, Lin, Yang, Bingyi, Ali, Sheikh Taslim, Tsang, Tim K., Shan, Songwei, Wu, Peng, Lau, Eric H.Y., Cowling, Benjamin J., and Meyers, Lauren Ancel

Subjects
Epidemics -- Statistics -- Risk factors -- United Kingdom, Disease transmission -- Statistics -- Risk factors, Health
Abstract

The United Kingdom has detected a variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent coronavirus disease (COVID-19), from samples initially collected in Kent on September 20 [...]

Published
2021
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35. Estimation of the Time-Varying Effective Reproductive Number of COVID-19 Based on Multivariate Time Series of Severe Health Outcomes.

Author

Young, Benjamin R, Ho, Faith, Lin, Yun, Lau, Eric H Y, Cowling, Benjamin J, Wu, Peng, and Tsang, Tim K

Subjects
COVID-19 pandemic, TIME series analysis, INTENSIVE care units, COVID-19, SARS-CoV-2
Abstract

The time-varying effective reproduction number (Rt at time t) measures the transmissibility of SARS-CoV-2 and is conventionally based on daily case counts, which may suffer from time-varying ascertainment. We analyzed Rt estimates from case counts and severe COVID-19 (intensive care unit admissions, severe or critical cases, and mortality) across 2022 in Hong Kong's fifth and sixth waves of infection. Within the fifth wave, the severe disease–based Rt (3.5) was significantly higher than the case-based Rt (2.4) but not in the sixth wave. During periods with fluctuating underreporting, data based on severe diseases may provide more reliable Rt estimates. [ABSTRACT FROM AUTHOR]

Published
2024
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36. Influenza Resurgence after Relaxation of Public Health and Social Measures, Hong Kong, 2023.

Author

Weijia Xiong, Cowling, Benjamin J., and Tsang, Tim K.

Abstract

Soon after a mask mandate was relaxed (March 1, 2023), the first post–COVID-19 influenza season in Hong Kong lasted 12 weeks. After other preventive measures were accounted for, mask wearing was associated with an estimated 25% reduction in influenza transmission. Influenza resurgence probably resulted from relaxation of mask mandates and other measures. [ABSTRACT FROM AUTHOR]

Published
2023
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38. Influenza Transmission Dynamics in Urban Households, Managua, Nicaragua, 2012-2014

Author

Gordon, Aubree, Tsang, Tim K., Cowling, Benjamin J., Kuan, Guillermina, Ojeda, Sergio, Sanchez, Nery, Gresh, Lionel, Lopez, Roger, Balmaseda, Angel, and Harris, Eva

Subjects
Influenza viruses -- Models -- Health aspects -- Analysis, Disease transmission -- Care and treatment -- Models -- Health aspects -- Analysis, Medical research -- Models -- Health aspects -- Analysis, Influenza -- Care and treatment -- Models -- Health aspects -- Analysis, Health
Abstract

Influenza virus is a respiratory pathogen of major medical and public health concern, causing an estimated 3-5 million cases of severe illness and 250,000-500,000 deaths annually worldwide (1). Households provide [...]

Published
2018
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