It has been reported that 15%–25% of patients with hematologic malignancies fail to make anti-spike (anti-S) antibodies in response to full dosing of SARS-CoV-2 mRNA vaccines (Greenberger et al., 2021; Griffiths and Segal, 2021). Patients with B cell malignancies are at the highest risk of not making anti-S antibodies. Although the complete immune response in B and T cells is not fully understood, these findings suggest that seronegative patients may be vulnerable to breakthrough infections. Patients with B cell malignancies are of particular concern because, in the pre-vaccine period of the pandemic, some patients with blood cancer who contracted COVID-19 had prolonged, severe infections; generated variant strains (Corey et al., 2021); and demonstrated significantly higher mortality rates compared to the general population (Bakouny et al., 2020; Vijenthira et al., 2020).

In a recent placebo-controlled trial, booster vaccination mediated an increase of anti-S antibodies and neutralizing antibodies in immunosuppressed patients who had solid organ transplantation (Hall et al., 2021). On August 12, 2021, the US Food and Drug Administration (FDA) amended the emergency use authorization for the mRNA vaccines (BNT162b2 and mRNA-1273) to allow the use of a booster dose for immunocompromised people. We report here the antibody responses to booster vaccination obtained prior to FDA authorization in 49 patients with B cell-derived hematologic malignancies.