Regional variation in mortality impact of the 2009 A(H1N1) influenza pandemic in China

BACKGROUND: Laboratory‐confirmed deaths grossly underestimate influenza mortality burden, so that reliable burden estimates are derived from indirect statistical studies, which are scarce in low‐ and middle‐income settings. OBJECTIVES: Here, we used statistical excess mortality models to estimate the burden of seasonal and pandemic influenza in China. METHODS: We modeled data from a nationally representative population‐based death registration system, combined with influenza virological surveillance data, to estimate influenza‐associated excess mortality for the 2004–2005 through 2009–2010 seasons, by age and region. RESULTS: The A(H1N1) pandemic was associated with 11·4–12·1 excess respiratory and circulatory (R&C) deaths per 100 000 population in rural sites of northern and southern China during 2009–2010; these rates were 2·2–2·8 times higher than those of urban sites (P < 0·01). Influenza B accounted for a larger proportion of deaths than pandemic A(H1N1) in 2009–2010 in some regions. Nationally, we attribute 126 200 (95% CI, 61 000–248 400) excess R&C deaths (rate of 9·4/100 000) and 2 323 000 (1 166 000–4 533 000) years of life lost (YLL) to the first year of A(H1N1)pdm circulation. CONCLUSIONS: The A(H1N1) pandemic posed a mortality and YLL burden comparable to that of interpandemic influenza in China. Our high burden estimates in rural areas highlight the need to enhance epidemiological surveillance and healthcare services, in underdeveloped and remote areas.