Introduction: The emergence of the Omicron variant of SARS-CoV-2 has posed significant challenges to global public health systems. Among vulnerable populations, allo-hematopoietic stem cell transplantation (allo-HSCT) recipients represent a particularly high-risk group due to their compromised immune systems. In this context, a retrospective cohort study conducted at the First Affiliated Hospital of Soochow University in China sought to evaluate the short-term implications of Omicron on allo-HSCT recipients. Here, we present a summary and discussion of the study's key findings.
Study Design: This observational cohort study, conducted at the First Affiliated Hospital of Soochow University, aimed to assess the impact of the Omicron variant of SARS-CoV-2 on allo-hematopoietic stem cell transplantation (allo-HSCT) recipients. Spanning from October 1, 2021, to March 15, 2023, the study was retrospective, capturing data during the period of relaxation of China’s “Zero-COVID” policy in December 2022.
Ethical considerations were paramount, with the study protocol approved by the Ethics Committee of the First Affiliated Hospital of Soochow University. Informed consent was obtained from each participant, ensuring adherence to ethical standards throughout the research process.
A total of 620 patients with various hematological conditions necessitating allo-HSCT were enrolled. These conditions included aplastic anemia, acute myeloid leukemia, acute lymphocytic leukemia, myelodysplastic syndrome, myeloproliferative neoplasm, and chronic myeloid leukemia.
The investigation characterized confirmed SARS-CoV-2 infections, as well as probable and suspected cases, among the study population. Utilizing univariate analyses, the study assessed factors associated with infection rates and disease severity. Severity levels of confirmed COVID-19 cases were categorized, with particular attention paid to critical infections.
Clinical characteristics of participants, including donor type and incidence of complications such as graft-versus-host disease (GVHD), were meticulously documented. These factors were examined for potential correlations with the risk and severity of SARS-CoV-2 infection.
The impact of vaccination against COVID-19 was analyzed, with data collected on the number of vaccine doses administered to patients prior to infection. The study’s comprehensive dataset facilitated in-depth evaluations across various patient demographics and clinical presentations.
Statistical analysis incorporated non-parametric tests and chi-squared/Fisher’s tests to compare infection rates and outcomes across non-severe, severe, and critical COVID-19 categories. This rigorous approach provided a robust framework to elucidate the contributing factors to infection severity in this vulnerable patient group.
Methods: The retrospective cohort study was conducted at the First Affiliated Hospital of Soochow University in China. It spanned from October 1, 2021, to March 15, 2023, capturing data during the period of relaxation of China’s “Zero-COVID” policy in December 2022.
Ethical approval was obtained from the Ethics Committee of the hospital, ensuring adherence to ethical standards throughout the research process. Informed consent was obtained from all participants.
The study enrolled 620 patients diagnosed with various hematological diseases necessitating allo-HSCT, including aplastic anemia, acute myeloid leukemia, acute lymphocytic leukemia, myelodysplastic syndrome, myeloproliferative neoplasm, and chronic myeloid leukemia.
Confirmed, probable, and suspected cases of SARS-CoV-2 infection were characterized among the study population. Univariate analyses were employed to assess factors associated with infection rates and the severity of the disease. Severity levels of confirmed COVID-19 cases were categorized, with a focus on critical infections.
Clinical characteristics of participants, such as donor type and incidence of complications like graft-versus-host disease (GVHD), were documented. These factors were analyzed for potential correlations with the risk and severity of SARS-CoV-2 infection.
The impact of vaccination against COVID-19 was evaluated, with data collected on the number of vaccine doses administered to patients prior to infection. Statistical analysis included non-parametric tests and chi-squared/Fisher’s tests to compare infection rates and outcomes across different categories of COVID-19 severity.
Results: Following the relaxation of China’s “Zero-COVID” measures, a significant portion of allo-HSCT recipients experienced SARS-CoV-2 infections. The study reported a 54.7% confirmed infection rate, with additional rates of probable and suspected infections. Severe and critical COVID-19 cases were observed in 13.0% and 5.3% of confirmed cases, respectively. The study identified a correlation between the time elapsed since HSCT and the rate of infection, indicating increased vulnerability closer to the transplant operation. Factors such as vaccination status, use of immunosuppressive therapy, and occurrence of acute graft-versus-host disease (aGVHD) significantly influenced the severity and criticality of infections.
Discussion: Despite ongoing precautions, allo-HSCT recipients were found to be highly susceptible to SARS-CoV-2 infection from the Omicron variant. The study underscores the importance of vaccination in mitigating severe outcomes, particularly in unvaccinated patients. While vaccination did not completely prevent infections, it offered a protective effect against severe disease. The findings highlight the need for tailored preventive and treatment strategies for immunocompromised individuals, emphasizing close monitoring and careful management, especially in those recently treated with immunosuppressive therapy or experiencing aGVHD.
Conclusion: The study provides critical insights into the infection profile of the Omicron variant among allo-HSCT recipients, emphasizing the continued vulnerability of this population despite ongoing precautions. The findings underscore the importance of vaccination and the need for personalized preventive and treatment approaches to mitigate the risk of severe COVID-19 outcomes in immunocompromised individuals. As viral threats continue to evolve, these insights will inform efforts to safeguard the health of allo-HSCT recipients amidst ongoing pandemics.
Collaborative Efforts: The collaborative efforts of researchers, including Man Qiao, Xiebing Bao, Su-ning Chen, and Dr. Depei Wu, reflect the interdisciplinary approach taken in this study conducted at the Department of Hematology at the First Affiliated Hospital of Soochow University. These individuals, along with others, have contributed significantly to the research efforts aimed at investigating the impact of the Omicron variant on allo-hematopoietic stem cell transplantation (allo-HSCT) recipients. Their affiliations with esteemed institutions such as the Jiangsu Institute of Hematology and the National Clinical Research Center for Hematologic Diseases underscore the depth of expertise brought to this study. While the specific contributions of each author may vary, their collective efforts highlight a comprehensive approach to study design, execution, analysis, and manuscript preparation. Equal contribution credits to key authors like Zhiyu Zhang, Man Qiao, and Xiebing Bao further emphasize the collaborative nature of this research endeavor. Detailed roles and responsibilities of each author, including Dr. Depei Wu, would be elucidated in the full-text publication, providing insights into their respective contributions to advancing our understanding of COVID-19 outcomes in allo-HSCT recipients.
