The CDC says the effectiveness of the flu vaccine last year (2021–22) was 14%.

Interim Estimates of 2021–22 Seasonal Influenza Vaccine Effectiveness — United States, February 2022, MMWR, CDC, 11 March 2022

VE [vaccine effectiveness] against outpatient medically attended ARI [acute respiratory infection] associated with influenza A virus types was 14%.
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Based on data from 3,636 children, adolescents, and adults with acute respiratory infection during October 4, 2021–February 12, 2022, seasonal influenza vaccination did not reduce the risk for outpatient respiratory illness caused by influenza A(H3N2) viruses that have predominated so far this season.

The FDA requires that any vaccine, including flu vaccine, be at least 50% more effective than a placebo in preventing disease.

What about the upcoming season?

So far, data from the US Flu Vaccine Effectiveness (VE) network, which consists of seven study sites, have not shown that the vaccine [for 2022-2023 season] is protective against influenza A. “We can say that it is not highly effective,” said Brendan Flannery, PhD, who leads the US Flu VE network for the Centers for Disease Control and Prevention (CDC).
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The vaccine is estimated to be 8% effective against preventing influenza A infection (95% CI, -31% to 36%) and 14% effective against preventing A/H3N2 infection (95% CI, -28% to 43%) for people aged 6 months and older.

This is a lot of vaccine being sold for not a lot of effectiveness. Do you think? It’s almost as if the CDC had some other incentive for promoting the drug other than public health.