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10. Impact of Delta Variant and Vaccination on SARS-CoV-2 Secondary Attack Rate Among Household Close Contacts

Author

Ng, Oon Tek, Koh, Vanessa, Chiew, Calvin J, Marimuthu, Kalisvar, Thevasagayam, Natascha May, Mak, Tze Minn, Chua, Joon Kiat, Ong, Shannen Si Hui, Lim, Yong Kai, Ferdous, Zannatul, Johari, Alifa Khairunnisa bte, Chen, Mark I-Cheng, Maurer-Stroh, Sebastian, Cui, Lin, Lin, Raymond Tzer Pin, Tan, Kelvin Bryan, Cook, Alex R, Leo, Prof. Yee-Sin, and Lee, Prof. Vernon JM

Published
2021
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11. Applied Statistical Learning in Python

Author

Chiew, Calvin J., Celi, Leo Anthony, editor, Majumder, Maimuna S., editor, Ordóñez, Patricia, editor, Osorio, Juan Sebastian, editor, Paik, Kenneth E., editor, and Somai, Melek, editor

Published
2020
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18. COVID-19 Severity and Waning Immunity After up to 4 mRNA Vaccine Doses in 73 608 Patients With Cancer and 621 475 Matched Controls in Singapore

Author

Tan, Wei Chong, primary, Tan, Janice Yu Jin, additional, Lim, Joline Si Jing, additional, Tan, Ryan Ying Cong, additional, Lee, Ainsley Ryan Yan Bin, additional, Leong, Fun Loon, additional, Lee, Soo Chin, additional, Chai, Louis Yi Ann, additional, Tan, Thuan Tong, additional, Malek, Muhammad Ismail Bin Abdul, additional, Ong, Benjamin, additional, Lye, David Chien, additional, Chiew, Calvin J., additional, Chng, Wee Joo, additional, Lim, Soon Thye, additional, Bharwani, Lavina D., additional, Tan, Iain Beehuat, additional, Sundar, Raghav, additional, and Tan, Kelvin Bryan, additional

Published
2023
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21. Long-term Cardiovascular, Cerebrovascular, and Other Thrombotic Complications in COVID-19 Survivors: A Retrospective Cohort Study.

Author

Lim, Jue Tao, En, Wee Liang, Tay, An Ting, Pang, Deanette, Chiew, Calvin J, Ong, Benjamin, Lye, David Chien Boon, and Tan, Kelvin Bryan

Subjects
THROMBOSIS risk factors, CEREBROVASCULAR disease risk factors, CARDIOVASCULAR diseases risk factors, COVID-19, IMMUNIZATION, CONFIDENCE intervals, POST-acute COVID-19 syndrome, COVID-19 vaccines, RETROSPECTIVE studies, ACQUISITION of data, CASE-control method, RISK assessment, SOUTHEAST Asians, RESEARCH funding, MEDICAL records, DESCRIPTIVE statistics, SURVIVAL analysis (Biometry), SYMPTOM burden, LONGITUDINAL method, DISEASE risk factors
Abstract

Background Growing evidence suggests that some coronavirus disease 2019 (COVID-19) survivors experience a wide range of long-term postacute sequelae. We examined the postacute risk and burden of new-incident cardiovascular, cerebrovascular, and other thrombotic complications after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in a highly vaccinated multiethnic Southeast Asian population, during Delta predominance. Methods This cohort study used national testing and healthcare claims databases in Singapore to build a cohort of individuals who had a positive SARS-CoV-2 test between 1 September and 30 November 2021 when Delta predominated community transmission. Concurrently, we constructed a test-negative control group by enrolling individuals between 13 April 2020 and 31 December 2022 with no evidence of SARS-CoV-2 infection. Participants in both groups were followed up for a median of 300 days. We estimated risks of new-incident cardiovascular, cerebrovascular, and other thrombotic complications using doubly robust competing-risks survival analysis. Risks were reported using 2 measures: hazard ratio (HR) and excess burden (EB) with 95% confidence intervals. Results We included 106 012 infected cases and 1 684 085 test-negative controls. Compared with the control group, individuals with COVID-19 exhibited increased risk (HR, 1.157 [1.069–1.252]) and excess burden (EB, 0.70 [.53–.88]) of new-incident cardiovascular and cerebrovascular complications. Risks decreased in a graded fashion for fully vaccinated (HR, 1.11 [1.02–1.22]) and boosted (HR, 1.10 [.92–1.32]) individuals. Conversely, risks and burdens of subsequent cardiovascular/cerebrovascular complications increased for hospitalized and severe COVID-19 cases (compared to nonhospitalized cases). Conclusions Increased risks and excess burdens of new-incident cardiovascular/cerebrovascular complications were reported among infected individuals; risks can be attenuated with vaccination and boosting. [ABSTRACT FROM AUTHOR]

Published
2024
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23. Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multicentre cohort study

Author

Chia, Po Ying, Ong, Sean Wei Xiang, Chiew, Calvin J., Ang, Li Wei, Chavatte, Jean-Marc, Mak, Tze-Minn, Cui, Lin, Kalimuddin, Shirin, Chia, Wan Ni, Tan, Chee Wah, Chai, Louis Yi Ann, Tan, Seow Yen, Zheng, Shuwei, Lin, Raymond Tzer Pin, Wang, Linfa, Leo, Yee-Sin, Lee, Vernon J., Lye, David Chien, and Young, Barnaby Edward

Published
2022
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24. Decreased Influenza Incidence under COVID-19 Control Measures, Singapore

Author

Soo, Roy Jiunn Jye, Chiew, Calvin J., Ma, Stefan, Pung, Rachael, and Lee, Vernon

Subjects
Disease transmission -- Control, Coronaviruses, Influenza -- Control, COVID-19, Health
Abstract

Public health measures, including public education and physical distancing, were implemented in Singapore to reduce transmission of coronavirus disease (COVID-19). However, instead of a lockdown, Singapore kept schools and workplaces [...]

Published
2020
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27. Erratum to “Impact of delta variant and vaccination on SARS-CoV-2 secondary attack rate among household close contacts” [The Lancet Regional Health – Western Pacific 17 (2021) 100299]

Author

Ng, Oon Tek, primary, Koh, Vanessa, additional, Chiew, Calvin J., additional, Marimuthu, Kalisvar, additional, Thevasagayam, Natascha May, additional, Mak, Tze Minn, additional, Chua, Joon Kiat, additional, Hui Ong, Shannen Si, additional, Lim, Yong Kai, additional, Ferdous, Zannatul, additional, Khairunnisa bte Johari, Alifa, additional, I-Cheng Chen, Mark, additional, Maurer-Stroh, Sebastian, additional, Cui, Lin, additional, Pin Lin, Raymond Tzer, additional, Tan, Kelvin Bryan, additional, Cook, Alex R., additional, Leo, Prof. Yee-Sin, additional, and Lee, Prof. Vernon J.M., additional

Published
2023
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33. Analysis of COVID-19 Incidence and Severity Among Adults Vaccinated With 2-Dose mRNA COVID-19 or Inactivated SARS-CoV-2 Vaccines With and Without Boosters in Singapore

Author

Ng, Oon Tek, primary, Marimuthu, Kalisvar, additional, Lim, Nigel, additional, Lim, Ze Qin, additional, Thevasagayam, Natascha May, additional, Koh, Vanessa, additional, Chiew, Calvin J., additional, Ma, Stefan, additional, Koh, Mingshi, additional, Low, Pin Yan, additional, Tan, Say Beng, additional, Ho, Joses, additional, Maurer-Stroh, Sebastian, additional, Lee, Vernon J. M., additional, Leo, Yee-Sin, additional, Tan, Kelvin Bryan, additional, Cook, Alex R., additional, and Tan, Chorh Chuan, additional

Published
2022
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35. Impact of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccination and Pediatric Age on Delta Variant Household Transmission

Author

Ng, Oon Tek, primary, Koh, Vanessa, additional, Chiew, Calvin J, additional, Marimuthu, Kalisvar, additional, Thevasagayam, Natascha May, additional, Mak, Tze Minn, additional, Chua, Joon Kiat, additional, Ong, Shannen Si Hui, additional, Lim, Yong Kai, additional, Ferdous, Zannatul, additional, Johari, Alifa Khairunnisa bte, additional, Cui, Lin, additional, Lin, Raymond Tzer Pin, additional, Tan, Kelvin Bryan, additional, Cook, Alex R, additional, Leo, Yee Sin, additional, and Lee, Vernon J M, additional

Published
2022
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37. Clinical and virological features of SARS-CoV-2 variants of concern: a retrospective cohort study comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta)

Author

Ong, Sean Wei Xiang, Chiew, Calvin J, Ang, Li Wei, Mak, Tze-Minn, Cui, Lin, Toh, Matthias Paul H S, Lim, Yi Ding, Lee, Pei Hua, Lee, Tau Hong, Chia, Po Ying, Maurer-Stroh, Sebastian, Lin, Raymond T P, Leo, Yee-Sin, Lee, Vernon J, Lye, David Chien, and Young, Barnaby Edward

Subjects
B.1.617.2, Cohort Studies, AcademicSubjects/MED00290, SARS-CoV-2, Major Article, COVID-19, severity, Humans, variants of concern, Retrospective Studies
Abstract

Background he impact of SARS-CoV-2 variants of concern (VOCs) on disease severity is unclear. In this retrospective study, we compared outcomes of patients infected with B.1.1.7, B.1.351, and B.1.617.2 with those with wild-type strains from early 2020. Methods National surveillance data from 1-January-2021 to 22-May-2021 were obtained from the Ministry of Health, and outcomes in relation to VOC were explored. Detailed patient level data from all patients with VOC infection admitted to our center between 20-December-2020 and 12-May-2021 were analyzed. Clinical outcomes were compared with a cohort of 846 patients admitted from January-April 2020. Results 829 patients in Singapore in the study period were infected with these 3 VOCs. After adjusting for age and sex, B.1.617.2 was associated with higher odds of oxygen requirement, ICU admission, or death (adjusted odds ratio (aOR) 4.90, [95% CI 1.43-30.78]). 157 of these patients were admitted to our center. After adjusting for age, sex, comorbidities, and vaccination, aOR for pneumonia with B.1.617.2 was 1.88 [95% CI 0.95-3.76]) compared with wild-type. These differences were not seen with B.1.1.7 and B.1.351. Vaccination status was associated with decreased severity. B.1.617.2 was associated with significantly lower PCR Ct values and longer duration of Ct value ≤30 (median duration 18 days for B.1.617.2, 13 days for wild-type). Conclusions There was a signal toward increased severity associated with B.1.617.2. The association of B.1.617.2 with lower Ct value and longer viral shedding provides a potential mechanism for increased transmissibility. These findings provide an impetus for the rapid implementation of vaccination programs.

Published
2021

38. Clinical and Virological Features of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.351 (Beta), and B.1.617.2 (Delta)

Author

Ong, Sean Wei Xiang, primary, Chiew, Calvin J, additional, Ang, Li Wei, additional, Mak, Tze Minn, additional, Cui, Lin, additional, Toh, Matthias Paul H S, additional, Lim, Yi Ding, additional, Lee, Pei Hua, additional, Lee, Tau Hong, additional, Chia, Po Ying, additional, Maurer-Stroh, Sebastian, additional, Lin, Raymond T P, additional, Leo, Yee Sin, additional, Lee, Vernon J, additional, Lye, David Chien, additional, and Young, Barnaby Edward, additional

Published
2021
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39. Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine-breakthrough infections: a multi-center cohort study

Author

Chia, Po Ying, primary, Xiang Ong, Sean Wei, additional, Chiew, Calvin J, additional, Ang, Li Wei, additional, Chavatte, Jean-Marc, additional, Mak, Tze-Minn, additional, Cui, Lin, additional, Kalimuddin, Shirin, additional, Chia, Wan Ni, additional, Tan, Chee Wah, additional, Ann Chai, Louis Yi, additional, Tan, Seow Yen, additional, Zheng, Shuwei, additional, Pin Lin, Raymond Tzer, additional, Wang, Linfa, additional, Leo, Yee-Sin, additional, Lee, Vernon J, additional, Lye, David Chien, additional, and Young, Barnaby Edward, additional

Published
2021
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40. Assessing the impact of non-pharmaceutical interventions on the transmissibility and severity of COVID-19 during the first five months in the Western Pacific Region

Author

Yeoh, Eng Kiong, primary, Chong, Ka Chun, additional, Chiew, Calvin J., additional, Lee, Vernon J., additional, Ng, Chiu Wan, additional, Hashimoto, Hideki, additional, Kwon, Soonman, additional, Wang, Weibing, additional, Chau, Nancy Nam Sze, additional, Yam, Carrie Ho Kwan, additional, Chow, Tsz Yu, additional, and Hung, Chi Tim, additional

Published
2021
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41. Clinical and Virological Features of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.351 (Beta), and B.1.617.2 (Delta).

Author

Ong, Sean Wei Xiang, Chiew, Calvin J, Ang, Li Wei, Mak, Tze Minn, Cui, Lin, Toh, Matthias Paul H S, Lim, Yi Ding, Lee, Pei Hua, Lee, Tau Hong, Chia, Po Ying, Maurer-Stroh, Sebastian, Lin, Raymond T P, Leo, Yee Sin, Lee, Vernon J, Lye, David Chien, and Young, Barnaby Edward

Subjects
*VIRAL physiology, *PUBLIC health surveillance, *COVID-19, *CONFIDENCE intervals, *AGE distribution, *RETROSPECTIVE studies, *COMPARATIVE studies, *SEX distribution, *DESCRIPTIVE statistics, *ODDS ratio, *POLYMERASE chain reaction, *LONGITUDINAL method
Abstract

Background The impact of SARS-CoV-2 variants of concern (VOCs) on disease severity is unclear. In this retrospective study, we compared the outcomes of patients infected with B.1.1.7, B.1.351, and B.1.617.2 with wild-type strains from early 2020. Methods National surveillance data from January to May 2021 were obtained and outcomes in relation to VOCs were explored. Detailed patient-level data from all patients with VOC infection admitted to our center between December 2020 and May 2021 were analyzed. Clinical outcomes were compared with a cohort of 846 patients admitted from January to April 2020. Results A total of 829 patients in Singapore in the study period were infected with these 3 VOCs. After adjusting for age and sex, B.1.617.2 was associated with higher odds of oxygen requirement, intensive care unit admission, or death (adjusted odds ratio [aOR], 4.90; 95% confidence interval [CI]: 1.43-30.78). Of these patients, 157 were admitted to our center. After adjusting for age, sex, comorbidities, and vaccination, the aOR for pneumonia with B.1.617.2 was 1.88 (95% CI:.95-3.76) compared with wild-type. These differences were not seen with B.1.1.7 and B.1.351. Vaccination status was associated with decreased severity. B.1.617.2 was associated with significantly lower polymerase chain reaction cycle threshold (Ct) values and longer duration of Ct value ≤30 (median duration 18 days for B.1.617.2, 13 days for wild-type). Conclusions B.1.617.2 was associated with increased severity of illness, and with lower Ct values and longer viral shedding. These findings provide impetus for the rapid implementation of vaccination programs. [ABSTRACT FROM AUTHOR]

Published
2022
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44. Clinical and Virological Features of SARS-CoV-2 Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta)

Author

Ong, Sean Wei Xiang, primary, Chiew, Calvin J., additional, Ang, Li Wei, additional, Mak, Tze-Minn, additional, Cui, Lin, additional, Toh, Matthias Paul HS, additional, Lim, Yi Ding, additional, Lee, Pei Hua, additional, Lee, Tau Hong, additional, Chia, Po Ying, additional, Maurer-Stroh, Sebastian, additional, Lin, Raymond Tzer Pin, additional, Leo, Yee-Sin, additional, Lee, Vernon J., additional, Lye, David Chien, additional, and Young, Barnaby E., additional

Published
2021
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45. Serial Heart Rate Variability Measures for Risk Prediction of Septic Patients in the Emergency Department

Author

Chiew, Calvin J., Wang, Han, Ong, Marcus E.H., Wong, Ting Hway, Koh, Zhi Xiong, Liu, Nan, and Feng, Mengling

Subjects
Aged, 80 and over, Male, Articles, Middle Aged, Prognosis, Risk Assessment, ROC Curve, Heart Rate, Sepsis, Humans, Female, Hospital Mortality, Triage, Emergency Service, Hospital, Aged
Abstract

In this study, we used serial heart rate variability (HRV) measures over 2 hours to improve the prediction of 30-day in-hospital mortality among septic patients in the emergency department (ED). We presented a generalizable methodology for processing and analysing HRV time series (HRVTS) data which may be noisy and incomplete. Feature sets were created from the HRVTS data of 162 patients with suspected sepsis using aggregation-based, deltabased and regression-based series-to-point transformations, and modelled over 100 random stratified splits. An optimized feature set comprising 12 selected HRVTS features performed better than baseline feature sets which only included patient demographics, vital signs and single time-point HRV measures taken at triage. This improved risk stratification approach could be used in the ED to identify high-risk septic patients for appropriate management and disposition.

Published
2020

46. Outbreak of Measles in a Residential Home for the Intellectually Disabled in Singapore in 2019

Author

Koh, Valerie T. J., primary, Chiew, Calvin J., additional, Xiang Ong, Sean Wei, additional, Nandar, Khine, additional, Lee, Anne, additional, Foo, Kelly, additional, Cui, Lin, additional, Ng, Yi Kai, additional, Pung, Rachael, additional, Lee, Tau Hong, additional, Said, Zubaidah, additional, Lin, Raymond, additional, Lye, David Chien, additional, Leo, Yee-Sin, additional, and Lee, Vernon, additional

Published
2020
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47. SARS-CoV-2 Infection among Travelers Returning from Wuhan, China

Author

Ng, Oon-Tek, primary, Marimuthu, Kalisvar, additional, Chia, Po-Ying, additional, Koh, Vanessa, additional, Chiew, Calvin J., additional, De Wang, Liang, additional, Young, Barnaby E., additional, Chan, Monica, additional, Vasoo, Shawn, additional, Ling, Li-Min, additional, Lye, David C., additional, Kam, Kai-qian, additional, Thoon, Koh-Cheng, additional, Kurupatham, Lalitha, additional, Said, Zubaidah, additional, Goh, Ethan, additional, Low, Constance, additional, Lim, Soon-Kok, additional, Raj, Pream, additional, Oh, Olivia, additional, Koh, Valerie T.J., additional, Poh, Cuiqin, additional, Mak, Tze-Minn, additional, Cui, Lin, additional, Cook, Alex R., additional, Lin, Raymond T.P., additional, Leo, Yee-Sin, additional, and Lee, Vernon J.M., additional

Published
2020
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50. Investigation of three clusters of COVID-19 in Singapore: implications for surveillance and response measures

Author

Pung, Rachael, primary, Chiew, Calvin J, additional, Young, Barnaby E, additional, Chin, Sarah, additional, Chen, Mark I-C, additional, Clapham, Hannah E, additional, Cook, Alex R, additional, Maurer-Stroh, Sebastian, additional, Toh, Matthias P H S, additional, Poh, Cuiqin, additional, Low, Mabel, additional, Lum, Joshua, additional, Koh, Valerie T J, additional, Mak, Tze M, additional, Cui, Lin, additional, Lin, Raymond V T P, additional, Heng, Derrick, additional, Leo, Yee-Sin, additional, Lye, David C, additional, Lee, Vernon J M, additional, Kam, Kai-qian, additional, Kalimuddin, Shirin, additional, Tan, Seow Yen, additional, Loh, Jiashen, additional, Thoon, Koh Cheng, additional, Vasoo, Shawn, additional, Khong, Wei Xin, additional, Suhaimi, Nur-Afidah, additional, Chan, Sherlynn JH, additional, Zhang, Emma, additional, Oh, Olivia, additional, Ty, Albert, additional, Tow, Charlene, additional, Chua, Yi Xian, additional, Chaw, Wei Liang, additional, Ng, Yixiang, additional, Abdul-Rahman, Farid, additional, Sahib, Shafiq, additional, Zhao, Zheng, additional, Tang, Cheryl, additional, Low, Constance, additional, Goh, Ee Hui, additional, Lim, Georgina, additional, Hou, Yan'an, additional, Roshan, Imran, additional, Tan, James, additional, Foo, Kelly, additional, Nandar, Khine, additional, Kurupatham, Lalitha, additional, Chan, Pei Pei, additional, Raj, Pream, additional, Lin, Yijun, additional, Said, Zubaidah, additional, Lee, Anne, additional, See, Cherie, additional, Markose, Jessey, additional, Tan, Joanna, additional, Chan, Guanhao, additional, See, Wanhan, additional, Peh, Xinyi, additional, Cai, Vincent, additional, Chen, Wen Kai, additional, Li, Zongbin, additional, Soo, Roy, additional, Chow, Angela LP, additional, Wei, Wycliffe, additional, Farwin, Aysha, additional, and Ang, Li Wei, additional

Published
2020
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