I have been taking 5-10,000 IU per day for the past couple of months.
I came to the conclusion after a fair amount of reading that was a little on the high side, and dialed back to 5000 IU every other day.
Yup, I’ve been on 4000 units of D3 for about a year. Almost never wear a diaper except where I think some jerk, mask-Nazi might yell and throw bricks at me. If I got this flu, I never knew it. Never had a flu vaccine either... ever.
4000 per day for the past 15 years. Not a sign of the flu.