Weakened humoral immune responses of inactivated SARS‐CoV‐2 vaccines in patients with solid tumors

Dear Editor Coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a pandemic. Cancer patients have a higher risk of poor outcomes for SARS-CoV-2 infection than the general population [1]. Vaccines were shown to effectively prevent SARS-CoV-2 infection, severe disease progression, and mortality. Inactivated SARS-CoV-2 vaccines (BBIBPCorV and CoronaVac) have been approved and widely used in China, with the former shown to be more effective than the latter [2]. Hence, there is an urgent need to investigate the safety and humoral immune responses of inactivated vaccines in cancer patients. Here, we performed a prospective observational study to evaluate receptor-binding domain IgG antibody (antiRBD-IgG), neutralizing antibodies (NAbs) and memory B cells (MBCs) responses, and monitor adverse events (AEs) in patients with solid tumors and healthy controls from 21-105 days after full-course of inactivated SARSCoV-2 vaccines. The detailed methods are described in the Supplementary File. From July to December 2021, 419 participants were enrolled in the study. Among them, 270 had solid tumors and 149 were healthy controls. The median age of the cancer patients was 49 years (interquartile range (IQR): 43-59), of whom 57.4% were females (Supplementary Table S1). The median time after 2nd-dose vaccination was 59.0 days (IQR: 36.5-83.0). Furthermore, 38.9% (105/270) of patients underwent anti-cancer therapy 3 months before the first vaccination dose. Of the 105 patients with ongoing treatment, 23 patients were treated with chemotherapy, 10 received immunotherapy, and 72 received other therapies.