I am on 1000 mg hydrea per day for chronic myelomonocytic leukemia and Langerhans cell hytiocytosis. I have had minimal side effects and good control of my blood counts and my LCH skin lesions. I was not advised by my doctors to stop the hydrea, and did not, for any of my 4 COVID vaccinations. I had a sore arm and one day slight fever with 2, 3, and 4th shots, but nothing serious and I don’t believe it to be related to the hydrea.