I too received my Moderna booster on 11/12 and developed whole body itching on 11/23. I tried oral steroids and Benadryl to no avail. Was seen by a dermatologist and was advised to take Zyrtec twice daily. Zyrtec helps tremendously but I do not want to take it daily. I have to be very careful not to scratch or the vicious cycle of itching starts. I hope this helps. Hoping this resolves soon.