Can a flu shot from 2 years ago provide some protection still?

So I requested the flu shot from my OB and she told me it’s too late in the season. I have to go to a course with 50 people in a crowded little room tomorrow. I had the flu shot 2 years ago and read that past flu shots are not as effective but can still provide some protection to your body. Anyone know if this is true? 😓.

Wish me luck this weekend 😭