Influenza-associated mortality for circulatory and respiratory causes during the 2013-2014 through the 2018-2019 influenza seasons in Russia

TL;DR

This study estimates influenza-associated deaths in Russia from 2013 to 2019, highlighting significant mortality, especially from circulatory causes, and suggests increased vaccination could reduce this burden.

Contribution

It provides the first detailed estimates of influenza-related mortality in Russia across multiple seasons using a standardized regression methodology.

Findings

Influenza caused an average of 17,636 circulatory deaths annually.

Influenza A/H3N2 was the leading contributor to mortality.

Mortality declined by 16.1% during seasons with higher vaccination coverage.

Abstract

Background: Information on influenza-associated mortality in Russia is limited. Methods: Using previously developed methodology (Goldstein et al., Epidemiology 2012), we regressed the monthly rates of mortality for respiratory causes, as well as circulatory causes linearly against the monthly proxies for the incidence of influenza A/H3N2, A/H1N1 and B (obtained using data from the Smorodintsev Research Institute of Influenza (RII)), adjusting for the baseline rates of mortality not associated with influenza circulation and temporal trends. Results: For the 2013/14 through the 2018/19 seasons, influenza circulation was associated with an average annual 17636 (95% CI (9482,25790)) deaths for circulatory causes and 4179 (3250,5109) deaths for respiratory causes, with the largest number of deaths (32298 (18071,46525) for circulatory causes and 6689 (5019,8359) for respiratory causes) estimated during the 2014/15 influenza season. The biggest contributor to both circulatory and respiratory influenza-associated deaths was influenza A/H3N2, followed by influenza B and A/H1N1. Compared to the 2013/14 through the 2015/16 seasons, during the 2016/17 through the 2018/19 seasons (when levels of influenza vaccination were significantly higher), the volume of influenza-associated mortality declined by about 16.1%, or 3809 annual respiratory and circulatory deaths. Conclusions: Influenza circulation is associated with a substantial mortality burden in Russia, particularly for circulatory deaths, with some reduction observed following the major increase in vaccination coverage. Those results support the potential utility of further extending the levels of influenza vaccination, the use of quadrivalent influenza vaccines, and extra efforts for protecting individuals with circulatory disease in Russia, including vaccination and the use of antiviral medications.