Excess Mortality of COVID-19 Pandemic Affected by Baby Boomers in Taiwan (Preprint)

BACKGROUND The aging population of Baby Boomers (born between 1946-1964) in Asia was faced with a great challenge on excessive all-cause mortality during COVID-19 pandemic. However, few studies were conducted to assess whether and to what extent excess deaths were affected by Baby Boomers susceptible to various SARS-CoV-2 mutants. OBJECTIVE We aimed to report a unique Taiwan scenario on how Baby Boomers affected all-cause excess deaths compared with non-Baby Boomers in different periods of SARS-CoV-2 mutants during COVID-19 pandemic. METHODS The interrupted time series design was proposed to build up the background mortality model before COVID-19 pandemic for predicting the expected all-cause deaths in comparison with the reported figures during the COVID-19 pandemic period base on 23,186,278 Taiwan residents in 2002 composed of 5,307,761 Baby Boomers aged 58-76 years and 17,878,517 non-Baby Boomers whose deaths preponderated in 77 years or older. The interaction between whether the cohort belongs to Baby Boomers and time trend was assessed by using the Poisson time-series regression model. RESULTS Given the background mortality that shows an increasing trend for Baby Boomers but constant trend for non-Baby Boomers, Baby Boomers had less 2% negative excess in 2020 (D614G) and more 3% excess deaths in 2021 (Alpha and Delta) compared with non-Baby Boomers. In large outbreaks of Omicron VOC in 2022, excess mortality rose up to 9% and 10% for Baby Boomers and non-Baby Boomers. Interestingly, Baby Boomers aged 58-76 year had the same 9% excess mortality as non-Baby Boomers aged 77 years or older. Baby Boomers had higher non-COVID-19 deaths than non-Baby Boomers (33% vs 29%). CONCLUSIONS Baby Boomers had as much as COVID-19 deaths and more non-COVID-19 deaths compared with the older non-Baby Boomers during COVID-19 pandemic. Low accessibility to medical care and insufficient medical capacity may account for substantial excess mortality in Baby Boomers.