Hello

The best thing to do is to seek advice from either the doctor who prescribed the cream or your GP.  They will be able to make a judgement about whether the possible risk of vaccination being a little less effective during your treatment, and therefor the risk of developing flu or becoming ill if you develop covid19 outweighs any risks in delaying or pausing treatment. This is something that would need to be decided on in an individual basis based on your circumstances.

Take care

Martin