Of the seven pts who did not achieve seroconversion after a median of 164 days from the second dose, all were currently on treatment for ITP (five on TPO-RA, one on TPO-RA and steroids, and one on AZT); three were over 75 years of age; three presented an associated immune cytopenia (two Evans syndrome and one cyclic neutropenia), and only one pt had been previously splenectomized. Here, TPO is linked to Cyclic neutropenia.