It’s not common for 35% of flu patients to experience those symptoms after 14-21 days have passed, as it is with Covid.

Is it not? I'd be interested to see statistics on this, because I was coughing for weeks after 2 of the 3 times I can remember catching the flu.

Flu characteristics are well understood and you should encounter no obstacles in doing that research yourself.

Okay:

> Uncomplicated influenza signs and symptoms typically resolve after 3-7 days for the majority of people, although cough and malaise can persist for >2 weeks, especially in elderly people and those with chronic lung disease.

https://www.cdc.gov/flu/professionals/acip/clinical.htm

Seems like over 14 days of flu symptoms is common.

“can persist” is not specified with a percentage of flu patients, and thus cannot be inferred to be “common” as you state from the evidence provided alone.

Precisely what overall percentage of flu patients across the general population experience continuing symptoms after 14-21 days?

(Any common influenza in any typical year in the past decade is fine.)

I'm not sure why you're assuming bad faith here. I attempted to and found no source indicating a proportion of flu cases with lingering symptoms, with most sources only giving vague statements that symptoms can persist. If you've done the research and found it easy, would you be interested to share the results?

You indicated that a given data point would be interesting and relevant to the conversation, and then didn’t indicate that you had invested any time in researching that data point to contribute it to the conversation. It’s poor form to shrug off that effort into others when your participation in this specific discussion on HN suggests you are both familiar enough and capable enough to attempt to look it up yourself. That you attempted to do so and couldn’t find the answer would have been relevant to mention in your comment, and knowing that now, I’m happy to retract my reply.

(However, regardless, I do not consider researching your line of reasoning to be a valuable use of the time I have available for this discussion, so I will not be doing so. It’s not personal at all, though I imagine that’s of no comfort. Perhaps someone else will do so; I see someone trying in another branch.)