Thread by @HelenBranswell

1. Short #flu thread.
@CDCgov's FluView came out today; data for the week ending Nov 27.
US Flu activity is ticking up. It's still not near most non-pandemic years, but flu is returning. 1.5% of clinical flu tests were positive, compared to .02% in 2020.
cdc.gov/flu/weekly/ind…

2. The data behind this chart give you a sense of the steady rise in flu positivity. In a pre-Covid year, you might expect to see a positivity rate of 4%, 8% or higher at this time of the #flu season, depending on whether the season was getting off to an early start or not.

3. So looking at the influenza-like illness curves, you can see that ILI rates (they include illnesses that are not #influenza) appear to be approaching the point where they cross the threshold into ILI season. But how much of that is flu?

4. In a normal year when you see huge spikes of ILI cases, you know a lot of that is due to #flu. But we're not in normal times. If you look at FluView's ILI map, you can see New Mexico is lit up — it has been for a few weeks. But the NM Health Dept website makes clear: Not flu.

5. The takeaway? It's still not a normal #flu year, but flu is around. Mostly #H3N2. So far it's mainly infecting kids & young adults. Those may not be groups in which flu vaccination rates are high. Might want to change that this year. Young kids haven't seen flu for awhile.