Estimation of excess mortality and hospitalisation associated with the 2009 pandemic influenza
L Yang1, CM Wong1, SSS Chiu2, BJ Cowling1, JSM Peiris1
1 School of Public Health, The University of Hong Kong
2 Department of Paediatrics and Adolescent Medicine, The University of Hong Kong
1. We estimated the excess mortality and hospitalisation associated with influenza strain A(H1N1)pdm09 using the classical Poisson model and the Poisson prediction modelling approach.
2. During the first wave of the pandemic from May to December 2009, 127 all-cause excess deaths were associated with the A(H1N1)pdm09, of which 115 were due to cardiovascular and respiratory diseases and 22 were due to pneumonia and influenza.
3. During the whole pandemic period from May 2009 to July 2010, 10 377 hospitalisations secondary to acute respiratory diseases and 7204 secondary to pneumonia and influenza were associated with A(H1N1)pdm09 infections.
4. An age shift towards children and younger people was found in A(H1N1)pdm09-associated excess hospitalisation for acute respiratory diseases and its subcategory pneumonia and influenza.
5. The age pattern of A(H1N1)pdm09-associated excess mortality was similar to that for seasonal influenza, with high mortality risk observed in people aged ≥65 years. This suggests that control measures adopted by the government were effective in reducing the mortality risk in younger age-groups.