Safety of SARS-CoV-2 Vaccines in Patients with Chronic Myeloid Leukemia: A Multicenter Survey in China
The global COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has had a devastating impact worldwide, with over 180 million confirmed cases and more than 3.9 million deaths as of July 4, 2021. Vaccination has emerged as the most effective strategy to control the pandemic. However, the safety and efficacy of SARS-CoV-2 vaccines in specific patient populations, such as those with hematological malignancies, remain poorly understood. This is particularly concerning for patients with chronic myeloid leukemia (CML), a chronic hematological tumor, as they were largely excluded from the clinical trials of most SARS-CoV-2 vaccines. Consequently, there is a lack of data to guide vaccination policies and individual decisions for this population. In China, where six SARS-CoV-2 vaccines are available, vaccination agencies often do not recommend or allow vaccination for hematological tumor patients, including those with CML. To address this gap, a multicenter cross-sectional survey was conducted to evaluate the safety of SARS-CoV-2 vaccines in CML patients in China.
Study Design and Methodology
The study was conducted across nine medical centers in China, involving 335 CML patients who had received SARS-CoV-2 vaccination. Online questionnaires were distributed to these patients through social media platforms. Each questionnaire included an informed consent form and 17 anonymous questions covering demographics, comorbidities, CML status and treatments, SARS-CoV-2 vaccination details, and adverse events (AEs). Patients voluntarily completed the questionnaires, and any missing or unclear data were verified through follow-up telephone calls, emails, or WeChat messages. The AEs were graded on a scale from Grade 1 (mild, not interfering with activity) to Grade 4 (potentially life-threatening, requiring emergency care or hospitalization). Logistic regression analysis was performed to examine associations between clinical parameters (gender, age, disease course, TKI types, comorbidities, and BCR-ABL1 levels) and vaccination-related factors (vaccine type and doses) and AEs. Statistical significance was set at P < 0.05, and analyses were conducted using SPSS version 22.0.
Patient Characteristics and Vaccination Details
All 335 respondents were in the chronic phase of CML, with 89.3% (299/335) achieving a major molecular response or deeper molecular response. The majority of patients (80.5%, 270/335) received the inactivated vaccine, while the remaining received other types of SARS-CoV-2 vaccines. A total of 75.5% (253/335) of respondents received one dose of the vaccine, and the rest received two doses. The median time between vaccination and questionnaire submission was seven days, ranging from 1 to 172 days.
Adverse Events and Safety Profile
Among the respondents, 19.1% (64/335) reported AEs following vaccination. The most common AE was injection-site pain, reported by 11.0% (37/335) of patients. Systemic AEs included fatigue (3.0%, 10/335), sleepiness (2.1%, 7/335), and flu-like symptoms (2.1%, 7/335). Other reported AEs included fever, headache, diarrhea, dizziness, hypogeusia, knee pain, lumbago, and gout attack. The median duration of AEs was one day, ranging from one to seven days. Two patients experienced Grade 2 flu-like symptoms, while all other AEs were Grade 1. Importantly, no Grade 3 or 4 AEs were reported. The AEs were not significantly associated with vaccine brand, TKI types, or other patient characteristics, except for younger age (P = 0.001), which may indicate a stronger immune response in younger individuals.
Comparison with Previous Studies
Previous studies have reported on the safety of SARS-CoV-2 vaccines in CML patients, but these were limited by small sample sizes. For example, Pimpinelli et al. (2021) assessed the safety and immunogenicity of the BNT162b2 vaccine (Pfizer–BioNTech) in 20 CML patients and found no Grade 3 or 4 AEs. Similarly, Harrington et al. (2021) reported no serious AEs in a cohort of 16 CML patients who received a single dose of the BNT162b2 vaccine. The current study, however, is the largest multicenter survey to date, involving 335 CML patients and evaluating five different SARS-CoV-2 vaccines. The incidence of AEs in this study was comparable to or lower than that reported in healthy individuals in previous phase 2 or 3 trials of inactivated vaccines in China (range: 19.0–48.3%). Importantly, no serious AEs were observed, reinforcing the safety of SARS-CoV-2 vaccines in CML patients.
Limitations of the Study
While the study provides valuable insights, it has several limitations. First, the “Survivorship bias” may have influenced the results, as deceased patients were excluded by default. However, previous trials of these vaccines have not reported vaccination-related deaths, suggesting a minimal likelihood of this bias. Second, the number of CML patients vaccinated with recombinant adenovirus or recombinant protein subunit vaccines was small, limiting the generalizability of findings for these vaccine types. Third, the study did not collect data on CML-related outcomes, such as BCR-ABL1 levels before and after vaccination, which could provide additional insights into the impact of vaccination on disease progression.
Conclusion
The findings of this multicenter survey suggest that SARS-CoV-2 vaccines are safe for patients with chronic phase chronic myeloid leukemia (CP-CML). The incidence of AEs in CML patients was comparable to that in healthy individuals, and no serious AEs were reported. These results provide reassurance for CML patients and healthcare providers regarding the safety of SARS-CoV-2 vaccination. However, further studies are needed to evaluate the long-term safety, effectiveness, and immunogenicity of these vaccines in CML patients, including their impact on disease progression and the development of protective antibodies.
doi.org/10.1097/CM9.0000000000001899
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