Title : Precision immunization in immunocompromised populations: Rethinking vaccine strategy across a heterogeneous risk spectrum

One of the most immunologically complicated populations in vaccination programs is immunocompromised individuals, including those receiving solid organ transplantation, hematopoietic stem cell transplantation, immunosuppressive or biologic therapy, as well as those with primary immunodeficiencies and those infected with HIV. Most immunization schedules are based on populations that are considered to be “immunocompetent” and do not reflect the differences in the extent and nature of immune impairment among these sub-groups; this can lead to greater risk of breakthrough infection, shorter duration of immunity and reduced Sero protection. This review collates recent evidence for precision approaches to immunization in immunocompromised individuals and provides a framework for how these fits with individual immune status to guide the choices of vaccine, dosage, and timing. A systematic review of the literature, clinical guidelines, and immunogenicity studies was performed using a narrative review of peer-reviewed publications from the last ten years, with emphasis on the comparison of live-attenuated and inactivated/subunit platforms, dose intensification, supplemental or additional dosing regimens, and biomarker-driven timing relative to immunosuppressive treatment cycles. Humoral and cell-mediated response parameters beyond conventional antibody levels such as antibody titers, seroconversion, and T-cell functional assays were emphasized in studies to reflect immune correlates. Results show that a size- fits-all strategy is not appropriate for this group. There are significant differences in humoral responses in transplant recipients and those receiving B-cell depleting therapy (BT), with the latter having a highly dampened response that can be partially enhanced by scheduling vaccinations around therapy cycles and by extra doses; patients with predominantly cell-mediated deficiencies may have some level of protection by T-cell responses which are not necessarily measured by antibody levels. Despite this, live-attenuated vaccines should not be given or should be carefully risk stratified in numerous subgroups, underlining the importance of selecting the vaccine platform, not just the vaccine diagnosis. New, biomarker and immunoprobing-based methods, such as assessment of lymphocyte subsets before vaccination and prior treatment exposure, hold promise in determining those most likely to benefit from more intensive or alternative treatment regimens. Immunization of vulnerable sub-populations demands the adoption of more flexible, individualized and biomarker informed approaches rather than a standard immunization timetable irrespective of the level of immune deficiency. A practical strategy for boosting protection in this high-risk population is to incorporate immune profiling into the pre- and post-vaccination care of these patients, and to enhance the integration of immunology and infectious disease and primary care teams.

Maimuna Sidi Muhammad is a Biology Laboratory Technologist at Skyline University Nigeria. She holds an M.Sc. in Medical Microbiology and is currently pursuing a Ph.D. in Medical Microbiology (Bacteriology). Her research interests include antimicrobial resistance (AMR), clinical bacteriology, environmental microbiology, and One Health. She has published research on the incidence of urinary tract infections among patients attending Aminu Kano Teaching Hospital, Kano, Nigeria. Maimuna is a member of the American Society for Microbiology (ASM) and is committed to advancing microbiological research, laboratory education, and innovative solutions to infectious disease challenges.