Implementation of Vaccination Strategies for Fragile Patients in Hospital: The Experience of a Tertiary Care Center With Hematology Patients

Abstract

INTRODUCTION 
Multiple myeloma is a hematological malignancy associated with a marked immunosuppression state and a consequent increased risk of vaccine-preventable infections. In this vulnerable population, the main guidelines recommend specific vaccination strategies, including influenza, pneumococcal, herpes zoster, and SARS-CoV-2 vaccinations, but in clinical practice, the implementation of these recommendations is often incomplete and uneven for several reasons.
OBJECTIVES
To describe vaccination coverage among patients with multiple myeloma treated at a referral center and to evaluate the level of implementation of recommended vaccination strategies in clinical practice. The impact of SARS-CoV-2 vaccination on overall coverage estimates and its relationship with survival was also analyzed.
METHODS
A retrospective observational study was conducted on a cohort of 379 patients diagnosed with multiple myeloma followed at the AOUP CT. For each patient, information regarding SARS-CoV-2, influenza, pneumococcal, herpes zoster, and meningococcal vaccinations was reconstructed from the clinical and vaccination database. Binary variables were created for each vaccine and an overall vaccination coverage variable, calculated both including and excluding SARS-CoV-2 vaccination. The demographic characteristics of the cohort and individual vaccine coverage were described. Associations between vaccination status, age groups (<50, 50–64, 65–74, ≥75 years), and gender were assessed using the chi-square test. An exploratory survival analysis using the Kaplan–Meier method was also performed, excluding SARS-CoV-2 vaccination.
RESULTS 
The cohort included 379 patients with multiple myeloma, with a slight male predominance (54.5%) and a median age at diagnosis of 66 years (IQR 57–74). Overall vaccination coverage was 75.5%; however, excluding SARS-CoV-2 vaccination, it dropped to 47.0%, highlighting the crucial role of COVID-19 vaccination campaigns. SARS-CoV-2 vaccination was the most frequent (73%), followed by influenza vaccination (42%), while pneumococcal (23%), herpes zoster (15%), and meningococcal (4%) coverage were significantly lower. Considering overall coverage, the association with age groups was significant (χ² = 8.57; p = 0.036), but lost significance when excluding the anti-SARS-CoV-2 component (χ² = 4.16; p = 0.245). Anti-pneumococcal and anti-Herpes Zoster coverage showed significant differences between age groups (p = 0.018 and p = 0.027), with lower levels in older subjects; no differences emerged by gender (p=0.680). Exploratory survival analysis, conducted excluding the anti-SARS-CoV-2 vaccine, showed better survival in vaccinated patients compared to unvaccinated ones (log- rank χ² = 67.03; p < 0.001).
CONCLUSIONS 
The results show that, in patients with multiple myeloma, overall vaccination coverage may mask insufficient implementation of recommended vaccinations other than the SARS-CoV-2 vaccine. The persistence of low coverage for some key vaccines and the observed improved survival rate among vaccinated subjects support the need to strengthen dedicated vaccination programs that are systematically integrated into hematology practice in this population.