Fever is the most common manifestation of CRS and several reports have consistently described the occurrence of a noninfectious fever within the first 5 days after Haplo‐SCT.9, 10, 11, 12, 13, 14 This process was firstly called infusion‐related febrile reaction and was found to be associated with a higher risk of engraftment syndrome and acute graft‐vs‐host‐disease (aGVHD).12, 13 Early post‐SCT fever correlated with the dose of CD34+ cells content of the graft12, 13 and more recently with the HLA II mismatching and myeloablative conditioning regimen.15 Here, CD34 is linked to congenital rubella syndrome.