Question: What are the rates of flu right now? Is the flu going up as well?

Answer: CDC keeps track of seasonal influenza spread in the US and shares its findings here. As of the latest data — week 41, ending 10/10 — “Seasonal influenza activity in the United States remains low.” Only two states have moderate levels of influenza activity — West Virginia and Iowa. It’s still way too early in the flu season to make heads or tails of influenza rates for the 2020–21 season. We’d expect flu to be low in October (see recent trends in Figure 1) and to be increasing as the flu season progresses. In the meantime, we can look at recent influenza trends in the US over the Spring/Summer “interseasonal” period and also look at recent trends from the southern hemisphere, which already experienced the height of this year’s influenza season.

Good news! According to a report recently published in CDC’s MMWR, “the percentage of U.S. respiratory specimens submitted for influenza testing that tested positive… has remained at historically low interseasonal levels (0.2% versus 1–2%). Data from Southern Hemisphere countries also indicate little influenza activity.” Scientific American published a short piece on this very topic a few weeks ago, quoting Greg Poland, an influenza expert at the Mayo Clinic who stated, “Never in my 40-year career have we ever seen rates … so low.” He goes on to describe how continuation of key public health measures could lead to the most dramatic drop in influenza cases in modern history (see Figure 2 for trends from South America). Even so, please go get your flu shot!

Figure 1. Seasonal Influenza in the USA, Week 41 of 2020–21, 2019–20, and 2018–19 influenza seasons (from CDC)

Figure 2. Seasonal Influenza trends in South America (from Scientific American)