Aging Populations, Viral Subtypes Contribute to Influenza Burden: Marco del Riccio, MD

To fully understand the burden of influenza, multiple factors must be considered, including prevention efforts, the circulation of the virus, population demographics, and other contingencies that might arise, according to Marco del Riccio, MD, of the University of Florence in Italy.

Watch part 1 to learn about the Flunomics report, published by Sanofi in collaboration with del Riccio, and what made the 2024-2025 influenza season stand out.

This transcript has been lightly edited for clarity; captions were auto-generated.

Transcript

Older adults accounted for a disproportionate share of hospitalizations and deaths. What factors do you think drove this impact?

Well, this is very complicated to say, in terms of understanding the burden of the disease, because there are many factors to be taken into consideration. In the long term, one, it's certainly age, I'd say. We know that the population, in general, in the world, and especially in high-income countries such as the US, is aging. So, we do have a structure that is modifying every year.

In terms of why this specific season in particular, it also depends on the subtype that is circulating and the characteristics of the subtype, the characteristics of the host, and how the host and virus interact. This is very important to take into consideration. The subtypes circulating were driving more severe cases, especially in older adults, who are the population that is most likely to develop a severe influenza that requires hospitalization or the ICU [intensive care unit].

Then, the other factor is that we are seeing a reduction in terms of use of preventive tools, in terms of vaccination coverage, for example. This is also a driving part, not all, of course, because it didn't decrease that much, but the decrease is also driving a little bit the numbers that we've seen for the last season, the 2024/2025 season.

So, let's say that to understand the burden of disease, there are many factors to be taken into consideration, including prevention, the circulation of the virus, the structure of the population, and other contingencies that might arise.