Aplastic Anemia Following COVID-19 Vaccination: A Systematic Review of Case Reports and Case Series.

Aplastic anemia (AA) is the prototypical bone marrow failure syndrome due to the destruction of hematopoietic stem cells by cytotoxic T cells. According to case reports, vaccines could lead to the development of AA. We conducted the present systematic review to evaluate cases of AA following vaccination against coronavirus disease (COVID-19). We searched the following databases: PubMed, Scopus, and EMBASE in English, Portuguese, and Spanish languages until April 24, 2023. Published reports and case series on AA following vaccination against COVID-19 were included. The Joanna Brigs Institute (JBI) was used to assess study quality and risk of bias. Six studies were selected from 102 research studies, and data were extracted according to the inclusion criteria. All case reports and case series reported the occurrence of AA following COVID-19 vaccination. AA events were mainly observed in vaccines with messenger ribonucleic acid technology (Moderna; Pfizer-BioNTech). AA was diagnosed by bone marrow biopsy, and severity was determined by Camitta criteria. All cases of AA were properly diagnosed. The sample size was small; therefore, further investigations are required to demonstrate and elucidate the complete pathophysiological mechanisms of AA development after receiving COVID-19 vaccination.