Publications by authors named "Chia Chong"

Objectives: Most studies on long-term sequelae of SARS-CoV-2 infection in children were conducted pre-Omicron and pre-dated vaccination rollout. We examined long-term risk of new-incident multi-systemic sequelae following SARS-CoV-2 Delta/Omicron infection in a multi-ethnic Asian paediatric population.

Methods: Retrospective cohort study of Singaporean children aged 1-17 years infected during Delta/Omicron BA.

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Aim: We report the epidemiology, treatment and outcomes of acute flaccid myelitis (AFM), including the first two cases of enterovirus (EV) D68 myelitis, in Singapore.

Methods: Retrospective observational study from a paediatric hospital in Singapore, from January 2012 to December 2022. Clinical, laboratory, neuroimaging and outcome data were analysed.

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Aim: Continuous monitoring of blood culture (BC) systems allows rapid detection of microbial growth. We aimed to determine differences in time to positivity (TTP) in BACTEC BC between organisms and whether a 36-h period was sufficient to detect all relevant pathogenic bacteria for children admitted to a tertiary care paediatric hospital.

Methods: This was a retrospective audit of positive aerobic (AE) and anaerobic (AN) BC from paediatric inpatients with available TTP from 1 August 2016 to 2 January 2019.

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Background: Primary hypogonadism is a recognised complication in survivors of testicular cancer. However, secondary hypogonadism can result from other causes that suppress the hypothalamic-pituitary axis, including obesity, high dose glucocorticoids, chronic end organ failure, and diabetes. The aim of this study was to explore low total serum testosterone in Australian survivors of testicular cancer and examine associations with body mass index, age, and prior chemotherapy use.

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Introduction: Information on the quality of health of children and younger persons (CYPs) after SARS-COV-2 infection remains scarce, especially from Asia. In this study, we utilised an online survey to investigate Long COVID prevalence in CYPs in Singapore.

Method: The study was an anonymised online survey of physical and functional symptoms, made available from 14 October 2022 to 15 January 2023.

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Background: Hybrid immunity to SARS-CoV-2, resulting from both vaccination and natural infection, remains insufficiently understood in paediatric populations, despite increasing rates of breakthrough infections among vaccinated children.

Methods: We conducted a prospective longitudinal study to investigate the magnitude, specificity, and cytokine profile of antigen-specific T cell responses elicited by breakthrough SARS-CoV-2 infection in a cohort of mRNA-vaccinated children (n = 29) aged 5-11. This longitudinal analysis involved six distinct time points spanning a 16-month period post-vaccination, during which we analysed a total of 159 blood samples.

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Background And Aims: There is a paucity of information on remdesivir (RDV) use in severe pediatric coronavirus disease 2019 (COVID-19). We aimed to explore the effectiveness of RDV as the cumulative proportion of pediatric COVID-19 patients deescalated from Day 5 of high dependency or intensive care unit (HD/ICU).

Methods: All children ≤18 years admitted to Singapore's largest pediatric hospital from January 1, 2020 to March 18, 2022 were reviewed retrospectively.

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The fight against hand, foot, and mouth disease (HFMD) remains an arduous challenge without existing point-of-care (POC) diagnostic platforms for accurate diagnosis and prompt case quarantine. Hence, the purpose of this salivary biomarker discovery study is to set the fundamentals for the realization of POC diagnostics for HFMD. Whole salivary proteome profiling was performed on the saliva obtained from children with HFMD and healthy children, using a reductive dimethylation chemical labeling method coupled with high-resolution mass spectrometry-based quantitative proteomics technology.

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Article Synopsis
  • Infants under 6 months are at a high risk of severe COVID-19, especially due to variants like Omicron (including XBB), but there's limited data on optimal maternal vaccination timing for safeguarding them.
  • This study in Singapore examined the effects of maternal vaccination (before or during pregnancy) on the rates of SARS-CoV-2 infection in infants born between January and September 2022, focusing on those whose parents had COVID-19.
  • Out of 7292 infants studied, the majority were born to vaccinated mothers, and while a small percentage were infected, the effectiveness of vaccination timing was an important factor in the overall analysis.
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Article Synopsis
  • The study examines the effectiveness of mRNA vaccines against SARS-CoV-2 infection in Singaporean children aged 1 to 4 years during the Omicron XBB variant wave.
  • Conducted over six months, it included data from 121,628 children to measure vaccine effectiveness, comparing vaccinated children to unvaccinated ones.
  • Results showed that fully vaccinated children had a 63.3% effectiveness against infection, while previously infected children with at least one vaccine dose had a 74.6% effectiveness against reinfections.
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There is little information on BNT162b2 vaccine-induced variant-specific immunogenicity, safety data and dynamics of breakthrough infections in pediatric populations. We addressed these questions using a prospective two dose BNT162b2 (10 mcg) vaccination cohort study of healthy children 5-11 years in Singapore. Follow up included blood samples at scheduled visits, daily vaccination symptom diary and confirmation of SARS-CoV-2 infection.

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Article Synopsis
  • The study investigates how well the BNT162b2 COVID-19 vaccine protects children and adolescents against omicron variants (BA.4, BA.5, and XBB), especially for those with previous infections.
  • It involves a comprehensive analysis of national health data from Singapore, focusing on confirmed SARS-CoV-2 infections and vaccination histories among children aged 5-17, while excluding certain groups like immunocompromised individuals and those with multiple infections.
  • Results are based on 135,197 participants, with researchers calculating the effectiveness of the vaccine through adjusted statistical methods to understand the protection levels conferred.
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Article Synopsis
  • Poliomyelitis, or polio, can lead to permanent paralysis but is preventable through vaccination; Singapore has been polio-free since 2000.
  • While wild polioviruses types 2 and 3 were eradicated globally in 2015 and 2019, resurgence of vaccine-derived poliovirus (VDPV) cases was noted in countries like Israel and the US in late 2022.
  • To sustain global eradication and prevent outbreaks, high vaccination coverage is crucial, with Singapore maintaining 96% coverage among 1-year-olds, and enhanced surveillance strategies are recommended for early detection of poliovirus transmission.
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Non-melanoma skin cancers (NMSCs) are the most common form of skin cancer worldwide. The global incidence of cutaneous squamous cell carcinoma (CSCC) is rising, with an estimated 2.4 million cases diagnosed in 2019.

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Introduction: Multisystem inflammatory syndrome in children (MIS-C) is a rare inflammatory syndrome with multisystem involvement affecting children exposed to COVID-19. This condition is rarely reported in East Asia and was not detected in Singapore until 2021. We present 12 cases of MIS-C diagnosed in KK Women's and Children's Hospital (KKH) from October 2021 to December 2021.

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Article Synopsis
  • A study evaluated the effectiveness of universal antigen rapid tests (ART) in preventing COVID-19 spread among hospitalized children aged 5 and older during the Omicron wave.
  • Out of 444 hospitalized pediatric patients, ART showed a high accuracy with 93.7% agreement with PCR tests, and sensitivity of 83.3% and specificity of 97.5%.
  • Findings suggested that while ART screening could help limit COVID-19 outbreaks in hospitals, its effectiveness is enhanced when combined with clinical symptoms and exposure assessment.
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Background: Singapore offered the BNT162b2 vaccine (tozinameran; Pfizer-BioNTech) to adolescents aged 12-17 years in May 18, 2021, and extended booster vaccines to this group in Jan 21, 2022. Literature on the effectiveness of primary series and booster vaccination among adolescents is scarce outside of Europe and North America. We aimed to determine primary series and booster vaccine effectiveness against SARS-CoV-2 infection and hospitalisation among adolescents in Singapore.

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Background: RAS mutation testing now routinely informs the optimal management of metastatic colorectal cancer (mCRC), specifically the finding of a RAS mutation defines patients who will not benefit from treatment with an epidermal growth factor receptor inhibitor. Over time more RAS genes have been tested and more sensitive techniques used.

Aims: To review routine care RAS testing and results over time.

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Introduction: Severe Combined Immunodeficiency (SCID) is generally fatal if untreated; it predisposes to severe infections, including disseminated Bacille-Calmette-Guerin (BCG) disease from BCG vaccination at birth. However, delaying BCG vaccination can be detrimental to the population in tuberculosis-endemic regions. Early diagnosis of SCID through newborn screening followed by pre-emptive treatment with anti-mycobacterial therapy may be an alternative strategy to delaying routine BCG vaccination.

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