Influenza-associated mortality in Thailand, 2006-2011.
BACKGROUND
Influenza-associated mortality in subtropical or tropical regions, particularly in developing countries, remains poorly quantified and often underestimated. We analyzed data in Thailand, a middle-income tropical country with good vital statistics and influenza surveillance data.


METHODS
We obtained weekly mortality data for all-cause and three underlying causes of death (circulatory and respiratory diseases, and pneumonia and influenza), and weekly influenza virus data, from 2006 to 2011. A negative binomial regression model was used to estimate deaths attributable to influenza in two age groups (<65 and ≥65 years) by incorporating influenza viral data as covariates in the model.


RESULTS
From 2006 to 2011, the average annual influenza-associated mortality per 100 000 persons was 4·0 (95% CI: -18 to 26). Eighty-three percent of influenza-associated deaths occurred among persons aged > 65 years. The average annual rate of influenza-associated deaths was 0·7 (95% CI: -8·2 to 10) per 100 000 population for person aged <65 years and 42 (95% CI: -137 to 216) for person aged ≥ 65 years.


CONCLUSIONS
In Thailand, estimated excess mortality associated with influenza was considerable even during non-pandemic years. These data provide support for Thailand's seasonal influenza vaccination campaign. Continued monitoring of mortality data is important to assess impact.
International Health Policy Program, Ministry of Public Health, Nonthaburi, Thailand.
Suchunya
S
Aungkulanon
Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Po-Yung
PY
Cheng
International Health Policy Program, Ministry of Public Health, Nonthaburi, Thailand.
Khanitta
K
Kusreesakul
International Health Policy Program, Ministry of Public Health, Nonthaburi, Thailand.
Kanitta
K
Bundhamcharoen
Naitonal Institute of Health, Nonthaburi, Thailand.
Malinee
M
Chittaganpitch
Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.
McCarron
M
Margaret
Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.|Thailand Ministry of Public Health - United States Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
Sonja
S
Olsen
Influenza; Thailand; mortality; tropical