Question: This infographic from Politico got me to wondering, if it weren’t for the flu vaccine, how deadly would the flu be?

Answer: I added the Politico infographic below for ease of reference. Good news [for making my job answering this question easy!] is that CDC’s Influenza Division estimates the burden of flu illness and death averted by vaccination in the United States. As CDC reports, “during 2018–2019, flu vaccination prevented an estimated 4.4 million influenza illnesses, 2.3 million influenza-associated medical visits, 58,000 influenza-associated hospitalizations, and 3,500 influenza-associated deaths.”

The number of infections and deaths averted will change yearly, largely depending on a) the severity of the flu; b) the vaccine effectiveness; and c) vaccine coverage. For example, the seasonal flu had high severity in 2017–2018, with CDC finding that “an estimated 8000 (95% CrI, 1100–21 000) influenza-associated deaths were prevented by vaccination (9% of expected deaths, overall; 95% CrI, 1%–20%). Influenza vaccination prevented an estimated 39% (95% CrI, 30%–45%) of influenza-related mortality in children aged 6 months–4 years.” If you want to read more, this paper published last year in Clinical Infectious Disease gives an overview of how such estimates are made and provides more detail on the 2017–18 flu infections averted, “Effects of Influenza Vaccination in the United States During the 2017–2018 Influenza Season.”

I suppose the upshot here is that if we were to try to compare apples to apples (e.g. two viruses that don’t have vaccinations), we’d still find that COVID is far more lethal than seasonal influenza.

Figure 1. COVID-19 is more deadly than seasonal flu (from Politico)