Seroconversion to mRNA SARS-CoV-2 Vaccines in Hematologic Patients

Area of Science:

• Immunology
• Hematology
• Vaccinology

Background:

• Hematologic patients exhibit diminished immune responses to SARS-CoV-2 vaccines.
• Predictors for successful seroconversion following vaccination in this population remain largely undefined.

Purpose of the Study:

• To identify predictors of seroconversion after SARS-CoV-2 mRNA vaccination in hematologic patients.
• To develop a predictive algorithm for vaccine non-response in this cohort.

Main Methods:

• Prospective cohort study of 393 hematologic patients receiving BNT162b2 or mRNA-1273 vaccines.
• Measurement of anti-Spike and anti-Nucleocapsid IgG titers at 5 weeks and 3 months post-vaccination.
• Multivariable analysis to identify factors associated with seroconversion.

Main Results:

• Overall, 72% of patients seroconverted, with 100% persistence at 3 months.
• Non-response was more prevalent in chronic lymphocytic leukemia (CLL) and lymphoma patients, and those on small molecules or monoclonal antibodies.
• Favorable predictors for seroconversion included diagnoses other than indolent lymphoma/CLL, absence of B-cell-depleting therapy, and normal IgG levels.

Conclusions:

• A predictive algorithm based on diagnosis, B-cell-depleting therapy, and IgG levels can identify hematologic patients at risk of non-response to SARS-CoV-2 mRNA vaccines.
• IgG levels and treatment regimens are potentially modifiable factors that warrant consideration for optimizing vaccine administration timing in hematologic patients.