What do the long-term trends in winter mortality reveal?

What is it about?

Excess winter mortality (EWM) is calculated from monthly (or weekly) deaths. The trends over the past 120 years are analysed. Around 1900 'winter' deaths seemed to peak in what we would now term as spring but have slowly shifted to winter over time. This method reveals that there is no evidence whatsoever that influenza pandemics (other than the Spanish flu) have caused more deaths than seasonal influenza. The method also shows that increasing levels of influenza vaccination is associated with no apparent effect on international EWM. Rising levels of obesity and multimorbidity in the elderly may be partly responsible

Featured Image

Photo by CDC on Unsplash

Photo by CDC on Unsplash

Why is it important?

EWM measures the NET effect of all factors operating each winter. Accurate assessment of influenza deaths is important since part of the cost benefit analysis for influenza vaccination relies on the number of deaths prevented by vaccination. While it was proposed that increasing obesity and multimorbidity in the elderly may be offsetting the effects of influenza vaccination the exact magnitude of these effects needs to be quantified. Given the fact that winter is a highly complex system it is also possible that influenza vaccination could be triggering unexpected outcomes. Clearly we need to differentiate exactly what is happening.

Perspectives