Suboptimal Response to Coronavirus Disease 2019 Messenger RNA Vaccines in Patients With Hematologic Malignancies: A Need for Vigilance in the Postmasking Era.

We measured severe acute respiratory syndrome coronavirus 2 immunoglobulin G responses in 67 patients with hematological malignancies after 2 messenger RNA vaccine doses. Forty-six percent were nonresponders; patients with B-cell chronic lymphocytic leukemia were at highest risk (77% nonresponders). Patients with hematological malignancies should continue wearing masks and socially distancing. Studies of revaccination, boosters, and humoral immune correlates of protection are needed.