Date: July 7, 2006 (Friday)
Time: 12:30 - 14:00 (sandwich lunch from 12:30 - 12:45; seminar begins at 12:45)
Venue: Seminar Room 6, LG/F, Laboratory Block, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong

Abstract:

• Introduction: Influenza virus infections cause excess morbidity and mortality in temperate countries. In the Northern and Southern Hemisphere, influenza epidemics occur nearly every winter, leading to an increase in hospitalization and mortality. However, little is known about the disease burden of influenza in tropical regions, e.g. Singapore, where the effect of influenza is thought to be less.
  
• Objective: To examine the influenza-associated mortality in tropical Singapore.
  
• Materials and Methods: Monthly counts of all-cause mortality, underlying cause-specific deaths for cardiovascular & respiratory (C&R) and pneumonia & influenza (P&I) occurred in Singapore during 1996-2003 were studied. Monthly percentages of influenza A sub-types (H1N1, H3N2), influenza B and respiratory syncytial virus positive tested in the same period were also used for analysis. The impact of influenza on mortality adjusted for number of days for each month, trends, seasonal patterns, temperature and relative humidity and over-dispersion were estimated from negative binomial regression models.
  
• Results: Influenza A (H3N2) was the predominant circulating influenza virus subtype, with consistently significant and robust effect on mortality. Influenza was associated with an annual mortality from all causes, from underlying P&I, and from underlying C&R conditions of 14.8 (95% confidence interval 9.8-19.8), 2.9 (1.0-5.0), and 11.9 (8.3-15.7) per 100,000 person-years, respectively. These results are comparable with observations in the United States and subtropical Hong Kong. An estimated 6.5% of underlying P&I deaths was attributable to influenza. The proportion of influenza-associated mortality was 11.3 times higher in persons age >65 years than in the general population.
  
• Conclusion: In our study, significant burden associated with influenza activities was showed. Our findings support the need for influenza surveillance and annual influenza vaccination for at risk population in tropical countries.
  
• Reference: Chow A, Ma S, Ling AE, Chew SK. Influenza-associated deaths in tropical Singapore. Emerging Infectious Diseases 2006;12:114-21.
  

Bio-sketch:

Dr Stefan Ma is the Senior Biostatistician at Singapore Ministry of Health. He received his undergraduate and master degrees in statistics from the University of Melbourne, Australia and the University of Hong Kong respectively, and a doctorate degree in biostatistics from the University of Hong Kong.

Dr Ma is a Fellow and a Chartered Statistician of the Royal Statistical Society of London, a member of the International Society of Clinical Biostatistics, a statistical advisor for the BioMed Central Open-access Journals, a honorary assistant professor of the Department of Community Medicine at the University of Hong Kong, an editorial board member of Singapore Epidemiological News Bulletin and a council member of Singapore Institute of Statistics. He was co-chairing an international workshop on mathematical modeling of infectious diseases at Institute of Mathematical Sciences, the National University of Singapore in Aug-Oct, 2005.

He has published over 30 scientific papers on public health. His research interests include applications of risk modeling in public health, health inequality, estimation of disease burden, and Poisson counts time-series regression models. He also has a keen interest in modeling transmission dynamics and control of infectious diseases.

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