# Fatal SARS-CoV-2 Reactivation After Allogeneic Hematopoietic Stem Cell Transplantation for Severe Aplastic Anemia

## TL;DR

A patient developed severe SARS-CoV-2 reactivation five months after initial infection, following a stem cell transplant, highlighting the need for monitoring.

## Contribution

This case report highlights SARS-CoV-2 reactivation after allogeneic hematopoietic stem cell transplantation, a previously under-recognized risk.

## Key findings

- A patient with severe aplastic anemia developed fatal SARS-CoV-2 reactivation five months after initial infection.
- Reactivation occurred post-transplantation during an immunosuppressive state, with no evidence of new infection.
- RT-PCR monitoring is suggested to detect reactivation and prevent fatal outcomes in similar cases.

## Abstract

SARS-CoV-2 has been reported to potentially remain in the lower respiratory tract for some time after it is no longer detectable in the upper respiratory tract, and this could be a source of reactivation. Reactivation of latent viral infections, such as cytomegalovirus and Epstein-Barr virus, after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is often a clinical problem. COVID-19 is caused by SARS-CoV-2 infection and has a high mortality rate in allo-HSCT recipients. However, little is known about SARS-CoV-2 reactivation following allo-HSCT. In this report, a patient with severe aplastic anemia first developed mild COVID-19 (day 0) with negative antigen test results on day 27. Three months later (day 97), the patient underwent allo-HSCT. Two months post-transplantation (day 157, i.e., five months after the initial infection), the patient developed rapidly progressive respiratory failure and was diagnosed with severe COVID-19. Since the patient was hospitalized and there was no obvious route of infection, we have concluded that reactivation of SARS-CoV-2, which had infected the patient five months earlier, occurred under an immunosuppressive state after allo-HSCT. Regarding allo-HSCT in patients who have previously developed COVID-19, careful monitoring using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) to detect SARS-CoV-2 could be useful for detecting SARS-CoV-2 reactivation and providing early treatment to prevent fatal COVID-19.