Influenza‐associated mortality in Yancheng, China, 2011‐15

Abstract

IntroductionThe Yangtze river delta in eastern China, centered on Shanghai, is one of the most populated regions of the world with more than 100 million residents. We examined the impact of influenza on excess mortality in Yancheng, a prefecture‐level city with 8.2 million population located 250 km north of Shanghai, during 2011‐2015.MethodsWe obtained individual data on deaths by date, age, sex, and cause in Yancheng from the Chinese Centers for Disease Control and Prevention, and used these to derive weekly rates of mortality from respiratory causes, respiratory and cardiovascular causes combined, and all causes. We used data on influenza‐like illnesses and laboratory detections of influenza to construct a proxy measure of the weekly incidence of influenza virus infections in the community. We used regression models to estimate the association of influenza activity with mortality and excess mortality by age, cause, and influenza type/subtype.ResultsWe estimated that an annual average of 4.59 (95% confidence interval: 3.94, 7.41) excess respiratory deaths per 100 000 persons were associated with influenza, which was 4.6% of all respiratory deaths in the years studied. Almost all influenza‐associated excess deaths occurred in persons ≥65 years. Influenza A(H3N2) had the greatest impact on mortality and was associated with around 50% of the influenza‐associated respiratory deaths in the 5 years studied.ConclusionsInfluenza has a substantial impact on respiratory mortality in Yancheng, mainly in older adults. Influenza vaccination has the potential to reduce disease burden, and cost‐effectiveness analysis could be used to compare policy options.

Advances in measuring influenza burden of disease

“…Eighteen population‐specific articles have been included in this Special Edition—including five from Asia, four from Africa, four from Europe, three from North America, and one each from South America and the Middle East . (Figure and Table ) This reflects a broad geographical breadth of new research, and these data will add to our understanding of the burden of disease worldwide, especially in LMICs.…”

“…The outcomes also varied across studies. The most common outcomes were deaths attributable to influenza, used in nine studies, and severe acute respiratory infections (SARI) or its equivalent, used in eight studies . Another seven studies measured excess or absolute hospitalizations due to influenza, and five studies measured community or outpatient visits .…”

“…For example, compared to hospitalizations, collecting accurate community‐based data on influenza may be challenging in dispersed populations or less‐resourced health systems. The different perspectives from the two studies in China also remind us that disease burden may vary within large countries with diverse populations …”

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