Serological responses against seasonal influenza viruses in patients with multiple myeloma treated or untreated with daratumumab after two doses of tetravalent vaccine.

Objectives: Daratumumab-treated myeloma patients may face increased seasonal influenza risk due to weakened postvaccination immune responses, especially with daratumumab treatment. We aimed to assess humoral responses to boosted influenza vaccination in daratumumab-treated or -untreated patients.

Methods: In a single-center study, we evaluated humoral responses (hemagglutination-inhibition assay) one month following a two-injection (4-weeks apart) influenza vaccination (standard dose) in 84 patients with multiple myeloma (40 with daratumumab in the past year).