The absence or dysfunction of the spleen is associated with a substantially increased risk of invasive infections that may rapidly progress to fulminant sepsis, including overwhelming post-splenectomy infection (OPSI), a medical emergency with high mortality. Although the risk is greatest in the first two years after splenectomy, it persists lifelong. Preventing infections in patients with anatomical or functional asplenia requires an integrated strategy that includes patient education, early recognition of symptoms, behavioral measures, antibiotic prophylaxis when indicated, and vaccination.

Post-splenectomy immunization has been shown to reduce OPSI incidence. Regional and international guidelines recommend vaccination against pneumococcus, Haemophilus influenzae type b, meningococcus (B and ACWY), herpes zoster, diphtheria-tetanus-pertussis, measles-mumps-rubella-varicella, and annual influenza. However, adherence to these recommendations is frequently suboptimal, often due to limited awareness among patients and healthcare professionals.

This study involves the intra-hospital vaccination team providing structured vaccination consultations to splenectomized patients hospitalized at the Fondazione Policlinico Universitario "A. Gemelli" IRCCS. During ward consultations, patients receive an educational intervention on asplenia-related infectious risks and preventive measures, supported by standardized informational materials. Effectiveness is evaluated using a pre-post questionnaire assessing knowledge and awareness. Patients completing the vaccination pathway at the outpatient clinic also complete a questionnaire assessing their experience with vaccination management in an intra-hospital setting.

This is a prospective, observational patient registry conducted at a single academic hospital. Adult patients undergoing splenectomy at the Fondazione Policlinico Universitario A. Gemelli IRCCS are consecutively identified through routine inpatient clinical workflows and enrolled after written informed consent.

Clinical, sociodemographic, and vaccination-related data are collected as part of standard care by the intra-hospital vaccination clinic and recorded in a dedicated database using predefined variables. Patient-reported outcomes are assessed using structured questionnaires administered before and after an educational intervention and, for patients completing the vaccination pathway, at the end of follow-up.

The registry allows longitudinal follow-up to monitor patient education, vaccination uptake, completion of recommended schedules, and post-discharge continuity of care. Follow-up data are collected during outpatient visits or, when necessary, via structured telephone interviews.

Data quality is ensured through standardized data collection procedures, use of validated questionnaires, and cross-verification of vaccination data using independent institutional sources. All data are pseudonymized and managed in compliance with applicable data protection regulations. The study is conducted according to Good Clinical Practice, Good Epidemiological Practice, and the Declaration of Helsinki.

Inclusion Criteria:

• Adult patients (≥18 years old)
• Patients splenectomized at FPG for whom a vaccination consultation is requested during hospitalization
• Patients who provide signed informed consent to participate in the study and for the processing of personal data for research purposes

Exclusion Criteria:

• Minor patients
• Lack of signed informed consent for participation in the study and for the processing of personal data for research purposes
• Patients splenectomized at other healthcare facilities

Patients splenectomized at the Fondazione Policlinico Universitario A. Gemelli IRCCS, identified during consultation activities in the requesting wards and/or managed by the hospital outpatient vaccination clinic for frail patients.