Difference in Immunogenic Responses to COVID-19 Vaccines in Patients With Cancer Receiving Chemotherapy Versus Nonchemotherapy Treatment

PURPOSE The COVID-19 pandemic has affected public health worldwide. The efficacy and safety of COVID-19 vaccines have been evaluated in the general population; however, data on patients with malignancies are limited. METHODS This prospective longitudinal observational cohort study was conducted between June and July 2021. Enrolled adult patients with cancer were divided into chemotherapy and nonchemotherapy groups. All participants were immunized with two doses of the ChAdOx1 nCoV-19 or CoronaVac COVID-19 vaccines. The primary outcome was a comparison of the immunogenicity (as assessed by spike protein [anti-S] immunoglobulin G [IgG] antibody titers) of two doses of COVID-19 vaccine in the chemotherapy and nonchemotherapy groups. The secondary outcomes included the anti-S IgG seroconversion rate and vaccine safety in both groups. RESULTS Among the 173 enrolled patients with solid cancer, after COVID-19 vaccination, the chemotherapy group had a significantly lower median anti-S IgG titer than the nonchemotherapy group (26 v 237 U/mL, P <.001). A statistically significant difference in anti-S IgG titer was found between groups vaccinated with CoronaVac (7 v 90 U/mL, P <.001), but no difference was found in those vaccinated with ChAdOx1 nCoV-19 (818 v 1061 U/mL, P =.075). The anti-S IgG seroconversion rate was significantly lower in the chemotherapy group than that in the nonchemotherapy group (78.9% v 96.5%, P =.001). No new or serious vaccine-related adverse events were reported. CONCLUSION Patients with solid cancer receiving a COVID-19 vaccine while undergoing chemotherapy had lower immunogenicity responses to vaccination than those who were vaccinated while undergoing non-chemotherapy treatment. No statistically significant difference was observed in the COVID-19 vaccine safety profiles between groups.