I got vaccinated for the flu last week. this week l did a blood test and my lym cells are 50.4(normal 20-45). is it possible this happens because of the vaccine? when should i repeat the exam to see if it gets normal again?

The lymphocyte count may or not be due to the vaccination. The question is why was the blood count done to begin with, could that be the cause of the count being abnormal? if there is a need for repetition the person that ordered the first test should know when and if there is need to repeat the test especially if other abnormalities. It does not need to be repeated if just because of the vaccine

All laboratory results need to be interpreted in the clinical context and the doctor who ordered the tests is usually in the best position to do that. Talk to the doctor who ordered the tests. Having said that, your absolute count may still be normal and the % may not be a cause for concern. Wish you good health!