COVID Vaccine Response Varies by Blood Cancer Type, Treatment


The study covered in this summary was published on as a preprint and has not yet been peer reviewed.

Key Takeaways

Why This Matters

  • COVID-19 vaccine efficacy and the effects anticancer treatments may have on that efficacy are not fully understood for people with blood cancers.

  • Understanding factors influencing vaccine effectiveness in this patient population can help guide management decisions.

Study Design

  • Investigators assessed antibody responses to two doses of the Pfizer or AstraZeneca vaccine in 53 patients with either ALL (26%), AML (62%), or HR-MDS (11%).

  • Patients were receiving or had recently completed systemic anticancer therapy.

  • Almost 40% of patients received intensive chemotherapy; 37.7% received venetoclax-combination therapy, 16.9% received nonintensive chemotherapy, and 5.6% received B-cell directed immunotherapy.

  • Vaccine doses were administered 8 to 12 weeks apart, in keeping with UK guidelines; 72% of patients received the Pfizer shot.

Key Results

  • Among patients with AML or HR-MDS, seroconversion rates and median anti-S antibody titers were higher than among patients with ALL (median, 291 U/mL, vs 5.06 U/mL).

  • Patients with AML or HR-MDS also showed significant increases in anti-S titers with two vaccine doses, which was not seen among those with ALL.

  • There was no difference in serologic response in patients receiving intensive or nonintensive chemotherapy, but titers were significantly reduced in patients with AML or HR-MDS who received venetoclax-based regimens compared to other therapies.

  • Patients with ALL who underwent intensive chemotherapy displayed almost uniformly low antibody titers (<10U/mL) after two vaccine doses, regardless of additional B-cell therapy.

  • Patients with acute leukemia can generate robust serologic responses to natural infection but not always to vaccination.

  • It’s not known whether the weaker vaccine response in ALL translates to less protection.



This is a summary of a preprint research study, “Antibody Responses to SARS-CoV-2 Vaccination in Patients With Acute Leukaemia and High Risk MDS on Active Anti-Cancer Therapies,” led by W. Y. Chan of University College London. The study has not been peer reviewed. The full text can be found at

M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who has worked for several major news outlets before joining Medscape and also an MIT Knight Science Journalism fellow. Email:

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