Efficacy and longevity of immune response to 3rd COVID-19 vaccine and effectiveness of a 4th dose in severely immunocompromised patients with cancer

Cancer patients show increased morbidity with COVID-19 and need effective immunization strategies. We demonstrate that a 3rd dose of COVID-19 vaccine leads to seroconversion in 57% of patients that were seronegative after primary vaccination. The immune response is durable as assessed by anti-S antibody titers, T-cell activity and neutralization activity against wild-type SARS-CoV2 and BA1.1.529 at 6 months of follow up. A subset of severely immunocompromised hematologic malignancy patients were unable to mount adequate immune response after the 3rd dose and were treated with a 4th dose in a prospective clinical trial which led to adequate immune-boost in 67% of patients. Low baseline IgM levels and CD19 counts were associated with inadequate seroconversion. Booster doses induced limited neutralization activity against the Omicron variant. These results indicate that vaccine booster-induced immunity is durable in cancer patients and additional doses can further stimulate immunity in a subset of hematologic malignancy patients. Statement of significanceWe demonstrate that a 3rd dose of vaccine leads to seroconversion in 57% of negative patients with durable immune responses at 6 months. A 4th dose of vaccine can seroconvert hematologic malignancy patients with higher baseline IgM and CD19 levels.

Development, clinical translation, and utility of a COVID-19 antibody test with qualitative and quantitative readouts

The COVID-19 global pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continues to place an immense burden on societies and healthcare systems. A key component of COVID-19 control efforts is serologic testing to determine the community prevalence of SARS-CoV-2 exposure and quantify individual immune responses to prior infection or vaccination. Here, we describe a laboratory-developed antibody test that uses readily available research-grade reagents to detect SARS-CoV-2 exposure in patient blood samples with high sensitivity and specificity. We further show that this test affords the estimation of viral spike-specific IgG titers from a single sample measurement, thereby providing a simple and scalable method to measure the strength of an individuals immune response. The accuracy, adaptability, and cost-effectiveness of this test makes it an excellent option for clinical deployment in the ongoing COVID-19 pandemic.