To calculate the excess mortality rates (EMRs) related to influenza in Chongqing from 2012 to 2018. The researchers collected weekly mortality data for all-cause and four underlying causes of death (circulatory and respiratory disease (CRD), pneumonia and influenza (P&I), chronic obstructive pulmonary disease (COPD), and ischemic heart disease (IDH), as well as influenza surveillance data. Chongqing had an estimated yearly average of 10025 influenza-related fatalities, accounting for 5.2 percent of total fatalities. The average EMR for influenza-related all-cause mortality was 33.5 per 100 000 people, and in separate cause-specific models, they ascribed EMRs of 24.7, 0.8, 8.5, and 5.0 per 100 000 people to CRD, P&I, COPD, and IDH, respectively. The estimated EMR for influenza B virus was 20.6, which was much higher than the rates for A(H3N2) and A(H1N1) pdm09 viruses, which were 5.3 and 7.5, respectively. The projected EMR for persons over the age of 65 was 152.3, which was substantially higher than the rate for those under the age of 65.

Influenza was linked to high EMRs in Chongqing, particularly among the elderly. When compared to A(H1N1)pdm09 and A(H3N2)pdm09, influenza B virus generated a considerably larger excess mortality impact (H3N2). To reduce illness burden, it is recommended that future seasonal influenza vaccination reimbursement policies in Chongqing be optimised.

Reference: https://www.tandfonline.com/doi/full/10.1080/21645515.2019.1693721