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Introduction
Kathy Leung currently works at the School of Public Health, The University of Hong Kong. Kathy does research in Epidemiology and Public Health.
Skills and Expertise
Publications
Publications (55)
Hong Kong utilized an elimination strategy with intermittent use of public health and social measures and increasingly stringent travel regulations to control SARS-CoV-2 transmission. By analyzing >1700 genome sequences representing 17% of confirmed cases from 23-January-2020 to 26-January-2021, we reveal the effects of fluctuating control measures...
Background: Transmission of respiratory pathogens such as SARS-CoV-2 depends on patterns of contact and mixing across populations. Understanding this is crucial to predict pathogen spread and the effectiveness of control efforts. Most analyses of contact patterns to date have focussed on high-income settings.
Methods: Here, we conduct a systematic...
Background
The cost-effectiveness of mammography screening among Chinese women remains contentious. Here we characterized breast cancer (BC) epidemiology in Hong Kong and evaluated the cost-effectiveness of personalized risk-based screening.
Methods
We used the Hong Kong Breast Cancer Study (a case-control study with 3,501 cases and 3,610 controls...
Digital proxies of human mobility and physical mixing have been used to monitor viral transmissibility and effectiveness of social distancing interventions in the ongoing COVID-19 pandemic. We develop a new framework that parameterizes disease transmission models with age-specific digital mobility data. By fitting the model to case data in Hong Kon...
Epidemic nowcasting broadly refers to assessing the current state by understanding key pathogenic, epidemiologic, clinical and socio-behavioral characteristics of an ongoing outbreak. Its primary objective is to provide situational awareness and inform decisions on control responses. In the event of large-scale sustained emergencies, such as the CO...
Understanding and quantifying the uncertainty of predictions from COVID-19 pandemic models is essential to inform public health decision making. This issue presents one such examination using the influential CovidSim model.
Two new SARS-CoV-2 lineages with the N501Y mutation in the receptor-binding domain of the spike protein spread rapidly in the United Kingdom. We estimated that the earlier 501Y lineage without amino acid deletion Δ69/Δ70, circulating mainly between early September and mid-November, was 10% (6-13%) more transmissible than the 501N lineage, and the 5...
Two new SARS-CoV-2 lineages with the N501Y mutation in the receptor binding domain of the spike protein have rapidly become prevalent in the UK. We estimated that the earlier 501Y lineage without amino acid deletion Δ69/Δ70 circulating mainly between early September to mid-November was 10% (6-13%) more transmissible than the 501N lineage, and the c...
Surrogate neutralization assays for SARS-CoV-2 that can be done without biosafety-33 level-3 containment and in multiple species are desirable. We evaluate a recently developed 34 surrogate virus neutralization test (sVNT) in comparison to 90% plaque reduction 35 neutralization tests (PRNT 90) in human, canine, cat and hamster sera. With PRNT 90 as...
Digital proxies of human mobility and physical mixing have been used to monitor viral transmissibility and effectiveness of social distancing interventions in the ongoing COVID-19 pandemic. We developed a new framework that parameterizes disease transmission models with age-specific digital mobility data. By fitting the model to case data in Hong K...
The SARS-CoV-2 lineage carrying the amino acid change D614G has become the dominant variant in the global COVID-19 pandemic. The rapid spread of the G614 mutant suggests that it may have a transmission advantage over the D614 wildtype. Using our previous epidemiological framework to analyze COVID-19 surveillance and sequence data, we estimated that...
Prolonged school closure has been adopted worldwide to control COVID-19. Such preemptive implementation was predicated on the premise that school children are a core group for COVID-19 transmission. Using surveillance data from the Chinese cities of Shenzhen and Anqing, we inferred that children aged 18 or below are only around half as susceptible...
The April 7, 2020, Wisconsin election produced a large natural experiment to help understand the transmission risks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of April 14, 2020, 1 551 711 total votes were cast ( https://bit.ly/2yWPhlF ), ¹ and 1 138 491 absentee ballots were returned as of April 21, 2020, ¹ suggesting that...
Many blood donation services around the globe maintain large archives of serum and/or plasma specimens of blood donations which could potentially be used for serologic surveillance and risk assessment of influenza. Harnessing this potential requires robust evidence that the outcomes of influenza serology in plasma, which is rarely used, is consiste...
As the COVID-19 pandemic continues, mathematical epidemiologists share their views on what models reveal about how the disease has spread, the current state of play and what work still needs to be done.
We analyze confirmed cases and new hospitalizations in Wisconsin in the weeks surrounding the April 7, 2020 election, and find no evidence of a surge in SARS-CoV-2 transmission.
Background
The ongoing coronavirus disease (COVID-19) pandemic has major impacts on health systems, the economy and society. Assessing infection attack rates in the population is critical for estimating disease severity and herd immunity which is needed to calibrate public health interventions. We have previously shown that it is possible to achiev...
As of 29 February 2020 there were 79,394 confirmed cases and 2,838 deaths from COVID-19 in mainland China. Of these, 48,557 cases and 2,169 deaths occurred in the epicenter, Wuhan. A key public health priority during the emergence of a novel pathogen is estimating clinical severity, which requires properly adjusting for the case ascertainment rate...
Background
As of March 18, 2020, 13 415 confirmed cases and 120 deaths related to coronavirus disease 2019 (COVID-19) in mainland China, outside Hubei province—the epicentre of the outbreak—had been reported. Since late January, massive public health interventions have been implemented nationwide to contain the outbreak. We provide an impact assess...
We conducted a retrospective study among 417 confirmed COVID-19 cases from Jan 1 to Feb 28, 2020 in Shenzhen, the largest migrant city of China, to identify the epidemiological and clinical features in settings of high population mobility. We estimated the median incubation time to be 5.0 days. 342 (82.0%) cases were imported, 161 (38.6%) cases wer...
As of February 13, 2020, there have been 59,863 laboratory-confirmed cases of COVID-19 infections in mainland China, including 1,367 deaths. A key public health priority during the emergence of a novel pathogen is estimating clinical severity. Here we estimated the symptomatic case-fatality risk (sCFR; the probability of dying from the infection af...
Background:
Since Dec 31, 2019, the Chinese city of Wuhan has reported an outbreak of atypical pneumonia caused by the 2019 novel coronavirus (2019-nCoV). Cases have been exported to other Chinese cities, as well as internationally, threatening to trigger a global outbreak. Here, we provide an estimate of the size of the epidemic in Wuhan on the b...
Background:
The initial cases of novel coronavirus (2019-nCoV)-infected pneumonia (NCIP) occurred in Wuhan, Hubei Province, China, in December 2019 and January 2020. We analyzed data on the first 425 confirmed cases in Wuhan to determine the epidemiologic characteristics of NCIP.
Methods:
We collected information on demographic characteristics,...
A novel coronavirus (2019-nCoV) causing severe acute respiratory disease emerged recently in Wuhan, China. Information on reported cases strongly indicates human-to-human spread, and the most recent information is increasingly indicative of sustained human-to-human transmission. While the overall severity profile among cases may change as more mild...
Background:
Hong Kong has been embroiled in increasingly violent social unrest since June, 2019. We examined the associated population mental health burden, risk factors, and health-care needs.
Methods:
In a population-based prospective cohort, adult participants aged 18 years or older were assessed at nine timepoints from 2009. Probable depress...
Objectives:
Enterovirus 71 (EV71) and coxsackievirus A16 (CA16) were responsible for 43.3% (235 123/543 243) and 24.8% (134 607/543 243) of all laboratory-confirmed hand, foot and mouth disease (HFMD) cases during 2010-2015 in China. Three monovalent EV71 vaccines have been licensed in China while bivalent EV71/CA16 vaccines are under development....
Background
Maintaining a stable, safe and sufficient blood supply is crucial to the healthcare system. Every year, seasonal influenza epidemics lead to substantial hospitalizations and pose intense pressure on blood transfusion service worldwide, especially in an ageing population of Hong Kong which often see bi‐annual influenza outbreaks. However,...
The spread of many respiratory infections is determined by contact patterns between infectious and susceptible individuals in the population. There are no published data for quantifying social contact patterns relevant to the spread of respiratory infectious diseases in Hong Kong which is a hotspot for emerging infectious diseases due to its high p...
Background
Hand, foot and mouth disease (HFMD) is a common illness in China that mainly affects infants and children. The objective of this study is to assess the economic cost and health-related quality of life associated with HFMD in China.
Method
A telephone survey of caregivers were conducted in 31 provinces across China. Caregivers of laborat...
Calculation of QALY loss, weighted cost and QALY loss.
(DOCX)
Number of laboratory confirmed HFMD cases in seven districts for mild, severe and fatal groups in China, 2013, together with weights used to achieve geographical representativeness in economic outcomes.
(DOCX)
Economic burden for HFMD patients in the telephone survey.
(DOCX)
Duration of illness for HFMD patients in each severity.
(TIF)
Health utility elicited by EQ-VAS for mild outpatient, mild inpatient and severe HFMD patients.
(TIFF)
Economic costs per episode for HFMD patient in China, 2013 (US dollars).
(DOCX)
QALY loss for HFMD patients in the telephone survey.
(DOCX)
Health utility elicited by EQ-5D for mild outpatient, mild inpatient and severe HFMD patients.
(TIFF)
Background:
Antivirals (eg, oseltamivir) are important for mitigating influenza epidemics. In 2007, an oseltamivir-resistant influenza seasonal A H1N1 strain emerged and spread to global fixation within 1 year. This event showed that antiviral-resistant (AVR) strains can be intrinsically more transmissible than their contemporaneous antiviral-sens...
Cross-reactive influenza-specific ADCC antibodies are readily detected in healthy adults. However, little is known about the kinetics of these ADCC responses. We utilized retrospective serial blood samples from healthy donors to investigate this topic. All donors had ADCC responses against the pandemic H1N1 and avian H7N9 HA despite being seronegat...
[This corrects the article DOI: 10.1371/journal.pmed.1001975.].
Background:
China accounted for 87% (9.8 million/11.3 million) of all hand, foot, and mouth disease (HFMD) cases reported to WHO during 2010-2014. Enterovirus 71 (EV71) is responsible for most of the severe HFMD cases. Three EV71 vaccines recently demonstrated good efficacy in children aged 6-71 mo. Here we assessed the cost-effectiveness of routi...
Background:
The seasonal influenza vaccine coverage rate in China is only 1.9 %. There is no information available on the economic burden of influenza-associated outpatient visits and hospitalizations at the national level, even though this kind of information is important for informing national-level immunization policy decision-making.
Methods:...
Seroprevalence survey is the most practical method for accurately estimating infection attack rate (IAR) in an epidemic such as influenza. These studies typically entail selecting an arbitrary titer threshold for seropositivity (e.g. microneutralization [MN] 1∶40) and assuming the probability of seropositivity given infection (infection-seropositiv...
MAVS is critical in innate antiviral immunity as the sole adaptor for RIG-I-like helicases. MAVS regulation is essential for the prevention of excessive harmful immune responses. Here we identify PCBP2 as a negative regulator in MAVS-mediated signaling. Overexpression of PCBP2 abrogated cellular responses to viral infection, whereas knockdown of PC...
