Publications by authors named "Leo Yee Sin"

Dengue virus infection can cause severe complications due to vascular leakage. Angiopoietin-like protein 4 (ANGPTL4) regulates vascular permeability, but its role in dengue pathogenesis is unclear. This study investigated the association between plasma ANGPTL4 levels and dengue severity in Singapore adults.

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Burkholderia pseudomallei is a pathogen expanding in geographic range. We performed a retrospective study analyzing the clinical, microbiologic features of culture-proven melioidosis, and predictors of mortality based on data from a Singapore tertiary hospital between 2006- 2016. We found ICU admission, bacteremia, and mechanical ventilation to be associated with mortality.

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Article Synopsis
  • A study was conducted in Singapore to explore whether having a prior dengue infection affects the risk and severity of getting COVID-19, particularly in a population where both diseases can overlap.
  • Researchers analyzed data from over 3 million individuals, looking at the relationship between prior dengue infections and subsequent SARS-CoV-2 cases during a time of increased COVID-19 transmission from Delta and Omicron variants.
  • The findings revealed that prior dengue infections slightly increase the risk of contracting SARS-CoV-2 and significantly heighten the likelihood of hospitalization and severe outcomes from COVID-19.
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Objectives: The emergence of new SARS-CoV-2 variants has led to the development of Omicron-targeting bivalent mRNA vaccines. It is crucial to understand how bivalent vaccines may improve antibody responses against new variants.

Methods: A total of 107 participants, who had three COVID-19 WT mRNA vaccine doses, were recruited, and given either a monovalent (WT) or a bivalent mRNA vaccination (Pfizer/BioNTech Bivalent (WT and BA.

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Background: While persistence of chronic symptoms following dengue infection has been documented in small prospective cohorts, population-based studies are limited. The post-acute risk of new-incident multi-systemic complications following dengue infection was contrasted against that following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in a multi-ethnic adult Asian population.

Methods: National testing and healthcare claims that databases in Singapore were utilized to build a retrospective population-based adult cohort with laboratory-confirmed infection during overlapping waves of SARS-CoV-2 and dengue transmission (1 July 2021 to 31 October 2022).

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There is a lack of evidence on the optimal administration of intravenous (IV) fluids in hospitalized adult dengue patients without compensated and hypotensive shock. This study utilized a well-established cohort of dengue patients to compare risks of progressing to severe dengue (SD) over time for patients who were administered IV fluid versus others who were not. We included adult patients (n = 4781) who were hospitalized for dengue infection from 2005 to 2008.

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The profiles of vaccine-induced dengue antibodies may differ from those produced following natural infection and could potentially interfere with the interpretation of diagnostic tests. We assessed anti-dengue IgG and IgM antibodies, and nonstructural protein 1 antigen profiles in the serum of adults who received a single dose of the tetravalent dengue vaccine TAK-003 as either an initially developed high-dose formulation or the standard approved formulation in a phase 2 study in Singapore (#NCT02425098). Immunoglobulin G and IgM profiles during the first 30 days postvaccination varied by baseline serostatus (microneutralization assay).

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Article Synopsis
  • SARS-CoV-2 variants and reduced vaccine immunity have led to increased cases of breakthrough infections, highlighting the need to understand vaccine protection mechanisms.
  • Researchers analyzed mRNA vaccinated individuals in Singapore during the Omicron surge to compare immune responses.
  • Findings suggest those who stayed uninfected developed a stronger variant-specific IgA response after booster shots, indicating IgA may play an important role in protecting against Omicron.
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Objective: At the beginning of the coronavirus disease (COVID-19) pandemic in Singapore, the strategy initially involved aggressive ring-fencing of infections, before pivoting towards managing recurrent local interspersed outbreaks of COVID-19. A key feature of Singapore's efforts to preserve health-care capacity was the implementation of the nationwide Home Recovery Programme (HRP), whereby patients were allowed to recover at home as long as they met certain criteria. The programme was centrally coordinated by Singapore's Ministry of Health and was supported by telemedicine providers, primary care physicians and government agencies.

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Identification of the risk factors and the high-risk groups which are most vulnerable is critical in COVID-19 disease management at a population level. Evaluating the efficacy of vaccination against infections is necessary to determine booster vaccination strategies for better protection in high-risk groups. In this study, we recruited 158 mRNA-vaccinated individuals during the Delta wave of SARS-CoV-2 infections in Singapore and examined the antibody profiles of infected individuals.

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Vaccine immunogenicity in transplant recipients can be impacted by the immunosuppressive (IS) regimens they receive. While BNT162b2 vaccination has been shown to induce an immune response in liver transplant recipients (LTRs), it remains unclear how different IS regimens may affect vaccine immunogenicity after a third BNT162b2 dose in LTRs, which is especially important given the emergence of the Omicron sublineages of SARS-CoV-2. A total of 95 LTRs receiving single and multiple IS regimens were recruited and offered three doses of BNT162b2 during the study period.

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Long-term complications from coronavirus disease 2019 (COVID-19) are concerning, as survivors can develop subclinical multiorgan dysfunction. It is unknown if such complications are due to prolonged inflammation, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination may reduce sequela. We conducted a prospective longitudinal study on hospitalized patients over 24 months.

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Article Synopsis
  • Dengue non-structural protein NS1 is crucial for diagnosing acute dengue infections, especially to differentiate it from Zika virus.
  • The study identified and characterized three new antibodies (A2, D6, D8) against NS1, along with a previously known antibody (Den3), noting their ability to recognize NS1 from various dengue serotypes.
  • A new capture ELISA was developed that specifically detects dengue NS1 using Den3 and D8, successfully identifying NS1 from multiple dengue strains without cross-reacting with Zika virus, suggesting its potential as a diagnostic tool.
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Introduction: Widespread mask use is an important intervention for control of the coronavirus disease 2019 pandemic. However, data on the factors affecting mask use are lacking. In this observational study, we evaluated the proportion of and factors influencing face mask use and related hygiene practices.

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Objectives: The objectives of this study were to describe the coronavirus disease caused by SARS-CoV-2 (COVID-19) reinfection evaluation algorithm used in the early phase of the pandemic in Singapore and analyze the clinical and laboratory characteristics of the cases evaluated.

Methods: We performed a retrospective case-control analysis including all COVID-19 cases evaluated for possible reinfection under the local COVID-19 reinfection evaluation programme between 1 June 2020-30 June 2021. Whole genome sequencing (WGS) was used as confirmatory testing.

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Early treatment of high-risk COVID-19 patients may prevent disease progression. However, there are limited data to support treatment of hospitalized or fully vaccinated patients with mild-to-moderate disease. In this retrospective cohort study, we studied the effect of early use of sotrovimab and remdesivir in high-risk hospitalized COVID-19 patients.

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Introduction: COVID-19 has a wide disease spectrum ranging from asymptomatic to severe. While humoral immune responses are critical in preventing infection, the immune mechanisms leading to severe disease, and the identification of biomarkers of disease progression and/or resolution of the infection remains to be determined.

Methods: Plasma samples were obtained from infections during the initial wave of ancestral wildtype SARS-CoV-2 and from vaccine breakthrough infections during the wave of Delta variant, up to six months post infection.

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The emergence of new SARS-CoV-2 variants, such as the more transmissible Delta and Omicron variants, has raised concerns on efficacy of the COVID-19 vaccines. Here, we examined the waning of antibody responses against different variants following primary and booster vaccination. We found that antibody responses against variants were low following primary vaccination.

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Article Synopsis
  • Serological testing in Singapore revealed that individuals who received smallpox vaccinations in childhood still have long-term humoral immunity, demonstrated by anti-vaccinia IgG levels and neutralizing activity.
  • There is a significant correlation between the levels of IgG and neutralizing titers, suggesting that IgG can serve as a surrogate marker for measuring immunity.
  • Following an imported monkeypox case in 2019, it was found that older Singaporeans vaccinated before 1981 retained higher levels of anti-vaccinia IgG, indicating potential protective immunity against orthopoxvirus outbreaks.
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Monkeypox is a global health emergency. Prior to 2022, there were few reports of monkeypox outside of endemic countries, which were mostly travel-related. Since May 2022, an exponential increase in monkeypox infections in previously non-endemic countries has been reported.

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