Mortality for circulatory and respiratory causes associated with influenza circulation in Russia during the 2013/14 through the 2018/19 seasons

TL;DR

This study estimates the mortality impact of influenza in Russia from 2013/14 to 2018/19, highlighting significant deaths especially from circulatory causes and the potential benefits of increased vaccination.

Contribution

It provides the first detailed estimates of influenza-associated mortality in Russia, using a regression model to quantify deaths for multiple influenza seasons.

Findings

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

Influenza led to about 4,179 respiratory deaths annually.

Increased vaccination correlated with a 16.1% decline in influenza-related deaths.

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 number of influenza-associated deaths 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.