Lowneutrophill count; Low leukocyte count; This spontaneous case was reported by a consumer and describes the occurrence of NEUTROPHIL COUNT DECREASED (Lowneutrophill count) and WHITE BLOOD CELL COUNT DECREASED (Low leukocyte count) in a 58-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.   Co-suspect product included non-company product PALBOCICLIB (IBRANCE) for an unknown indication.    No Medical History information was reported.   On an unknown date, the patient received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. and PALBOCICLIB (IBRANCE) (unknown route) 1 dosage form. On an unknown date, the patient experienced NEUTROPHIL COUNT DECREASED (Lowneutrophill count) (seriousness criterion medically significant) and WHITE BLOOD CELL COUNT DECREASED (Low leukocyte count) (seriousness criterion medically significant). At the time of the report, NEUTROPHIL COUNT DECREASED (Lowneutrophill count) and WHITE BLOOD CELL COUNT DECREASED (Low leukocyte count) outcome was unknown.   DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Neutrophil count: low Low. On an unknown date, White blood cell count: low Low.         No concomitant medication was provided by reporter. No treatment drug was provided by reporter.  Patient stated that the Ibrance tablets that were exposed to higher temperatures tasted off, so she stopped taking them.  Patient received two Covid-19 vaccines manufactured by Moderna while also taking Ibrance.  Reporter did not allow further contact.  Company Comment:  This spontaneous case concerns a 58-year-old female patient with concomitant use of Palbociclib (Ibrance), who experienced the unexpected, serious (medically significant) events of Neutrophil count decreased (reported as Low neutrophil count), and White blood cell count decreased (reported as Low leukocyte count) on an unknown date after receiving a dose of mRNA-1273 vaccine. Latency between vaccine and events cannot be established.  Patient received a total of 2 doses mRNA-1273 vaccine administered on unknown dates.  The concomitant use of Palbociclib (Ibrance) remains a confounder as it may cause low white blood cell count. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns a 58-year-old female patient with concomitant use of Palbociclib (Ibrance), who experienced the unexpected, serious (medically significant) events of Neutrophil count decreased (reported as Low neutrophil count), and White blood cell count decreased (reported as Low leukocyte count) on an unknown date after receiving a dose of mRNA-1273 vaccine. Latency between vaccine and events cannot be established.  Patient received a total of 2 doses mRNA-1273 vaccine administered on unknown dates.  The concomitant use of Palbociclib (Ibrance) remains a confounder as it may cause low white blood cell count. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.