P164 | REAL-WORLD APPROACHES TO VACCINATION AND ANTIMICROBIAL PROPHYLAXIS IN MULTIPLE MYELOMA: A SURVEY ACROSS EMN CENTERS

Patients with hematological malignancies are at increased risk for infections, including those preventable through vaccination, such as influenza and invasive pneumococcal disease. This risk begins to rise at the monoclonal gammopathy of undetermined significance (MGUS) stage and increases significantly in patients with active multiple myeloma (MM), particularly upon initiation of anti-myeloma therapy. A population-based study demonstrated a tenfold higher risk of viral infections and a sevenfold higher risk of bacterial infections in MM patients. Profound immune suppression—especially during uncontrolled disease—contributes to this vulnerability, which is further exacerbated by anti-myeloma therapies impairing T-cell function and antibody production. Administering vaccines during periods of minimal immunosuppression may help mitigate this risk. However, differing practices and perceptions among healthcare professionals can influence vaccine uptake. This study aimed to assess the current approaches to vaccination and antimicrobial prophylaxis across centers affiliated with the European Myeloma Network (EMN). A survey exploring vaccination strategies and clinicians' attitudes was distributed to EMN centers between September and December 2024. Responses were received from 68 centers (63%). All centers provided information regarding vaccination protocols and antimicrobial prophylaxis. Prior to initiating therapy, 72% of clinicians review patients’ vaccination histories, focusing primarily on pneumococcal (96%), inactivated influenza (91%), varicella-zoster virus (85%), Haemophilus influenzae (42%), and hepatitis B (35%) vaccines. Meningococcal vaccination is recommended in only 18% of cases, while limited attention is given to diphtheria, tetanus, pertussis (DTP), and measles, mumps, rubella (MMR) vaccines. Influenza vaccination is routinely recommended in 85% of centers, and pneumococcal vaccination is universally recommended in 56%, although 25% of centers restrict it to patients aged over 65. SARS-CoV-2 vaccination status is assessed in 95% of centers, with most administering booster doses even during maintenance therapy. The recombinant subunit vaccine for varicella-zoster virus is recommended in 88% of centers for eligible patients, and antiviral prophylaxis is maintained in 61% of these cases. The QuantiFERON test is used before starting therapy in 31% of cases, and in 52% of patients with a history of pulmonary disease. Regarding antiviral prophylaxis, acyclovir is prescribed at 400 mg once daily in 43% of cases and 400 mg twice daily in 40%. Valacyclovir (500 mg daily) is used in only 2% of centers. Sulfamethoxazole/trimethoprim is prescribed in 64% of centers, and in 33% of centers only for selected cases. Immunoglobulin therapy is considered in patients with IgG levels below 3.5 g/dL and recurrent infections in 59% of centers, with intravenous administration used in 86% of cases. This survey underscores the widespread awareness among clinicians of the importance of infection prevention in MM, particularly through vaccination and antimicrobial prophylaxis. However, it also reveals notable variability in clinical practices, highlighting the need for standardized guidelines to harmonize preventive care across institutions.