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Published on: November 10, 2023
Influenza-associated Excess Mortality Associated With Influenza B in Hong Kong, 2014-2023
Jessica Y Wong1, Justin K Cheung1, A Danielle Iuliano2
1WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
Background:
Influenza B epidemics can have substantial public health impact. We aimed to estimate the mortality burden associated with influenza B virus infections over a 7-year period in Hong Kong.
Methods:
Age-, cause-specific and all-cause mortality rates in Hong Kong from 2014 through 2023 were fit to linear regression models with influenza B virus lineages as covariates. The influenza-associated excess mortality from influenza B viruses was estimated as the difference between fitted death rates with or without influenza B virus activity.
Results:
Between 2014 and 2023, the annual respiratory excess mortality rate associated with influenza B was 3.5 (95% credible interval (CrI): 2.4, 4.6) per 100 000 person-years. We estimated an average of 260 (95% CrI: 180, 340) excess deaths associated with influenza B annually from 2014 through 2023, with a majority of the excess deaths occurring in adults ≥65 years of age. Influenza B/Yamagata epidemics were associated with more excess deaths than influenza B/Victoria, and the majority of influenza-associated deaths were from respiratory causes.
Conclusions:
Influenza B was associated with mortality burden each year, mainly among older adults, from 2014-2023. The disappearance of influenza B/Yamagata since 2020 suggests that influenza B burden will be lower in the future.
