# Follow-up of humoral and cellular immune responses after the third SARS-CoV-2 vaccine dose in multiple myeloma patients

## TL;DR

This study tracks immune responses in multiple myeloma patients after a third SARS-CoV-2 vaccine dose, finding that immunity declines over time but can be boosted by additional vaccines or infections.

## Contribution

The study provides new insights into the durability of humoral and cellular immunity in multiple myeloma patients after third SARS-CoV-2 vaccination.

## Key findings

- Neutralizing antibodies and CD8+ T cell responses declined significantly after 26 weeks post-third dose.
- Additional vaccination or breakthrough infection boosted antibody levels and stabilized T cell responses.
- Patients with only three doses had higher breakthrough infection rates during 32 weeks of follow-up.

## Abstract

The stability of immune responses to SARS-CoV-2 vaccines, especially concerning the cross-reactive recognition of the Omicron variant, remains incompletely characterized in multiple myeloma (MM) patients. This study evaluated humoral responses in 29 MM patients and cellular responses in a subset of 19 MM patients, specific to Wuhan and Omicron spike proteins, between 16 and 26 weeks following the third vaccine dose. After 26 weeks, we highlighted a significant reduction in the neutralizing antibodies to both spikes and the percentages of IFN-γ+CD107a+ spike-specific CD8+ T cells. On the other hand, patients who underwent an additional stimulation between the two time points, through either a fourth vaccine dose or breakthrough infection, showed a significant increase in neutralizing antibodies and stable levels of cytotoxic CD8+ T cells. Additionally, those with only three doses experienced a higher rate of breakthrough infections during the 32-week follow-up period. These findings underscore the waning of vaccine-induced immunity over time and may help benefit-risk evaluation in vaccination strategies in MM patients.