Beyond Antibodies: Influenza Vaccine Induced T-Cell Response in Hematological Malignancy— Commentary on Insights From Hall et al

To the Editor—We read with great interest the recent article by Hall et al [1], which provides one of the most detailed contemporary immunogenicity assessments of influenza vaccination in patients with hematologic malignancies. The randomized comparison of adjuvanted versus standard-dose quadrivalent inactivated influenza vaccine did not demonstrate differences in immune responses between vaccine formulations or between single versus booster vaccination schemes, but it offered a unique and timely window into the divergent humoral and cellular immune responses in this highly vulnerable population. From a clinical point of view, this study is particularly important because patients with a hematological malignancy diagnosis face a substantially higher in-hospital mortality from seasonal influenza, with mortality rates reported up to 10-fold higher than in the general population [2]. At the same time, influenza vaccine effectiveness is markedly reduced in these patients, making it crucial to understand how their compromised immune system responds to vaccination. The authors' innovative work covers multiple areas of research that have not been well understood yet. So far, most studies in the field of influenza vaccine responses in cancer patients have focused on patients with solid tumors. Furthermore, the investigation of the influenza-specific T-cell response brings novel insights to immune responses in patients with hematological malignancies, where mainly humoral immune responses have been studied. Additional exploration of the T-cell response shows promise, because clinical data in older adults indicate that T-cell responses after influenza vaccination predict protection against infection more accurately than antibody titers [3].