Efficacy of 20-valent pneumococcal vaccination in chemotherapy patients: A first real world report.

452 Background: Patients with cancer receiving cytotoxic chemotherapy are at a high risk of infection, the leading cause of morbidity and mortality in this population. Community-acquired pneumonia (CAP) in patients with underlying cancer is associated with worse outcomes, irrespective of neutropenia. Studies have shown that patients with cancer and CAP have increased requirements for vasopressor support. Methods: We initiated a quality improvement (QI) project at our cancer center to evaluate the rates of pneumococcal vaccination among cancer patients. The primary analysis was to identify whether the one-dose 20-valent pneumococcal vaccine (PCV20) would improve vaccination rate. Following the initial analysis, PCV20 was offered to all patients before starting therapy. Secondary analysis included hospitalization, ICU admission, and outpatient rates for pneumonia in patients receiving chemotherapy (chemo) and non-chemotherapy anticancer medications (non-chemo). Patients diagnosed with CAP within 3 months of vaccination and co-infection with viral infection were excluded. Results: For the primary analysis, data from December 2021 to March 2023 were included. In September 2022, our institution implemented PCV20 as the preferred pneumococcal vaccination. Of the 135 patients, 21% had completed vaccination before September 2022. With PCV20, complete vaccination increased to 66%. For secondary analysis, data from January 2023 to December 2024 identified 156 patients (median age 70 years) who had received the PCV20. In this cohort, 99 (63%) patients were in the chemo group and 57 (37%) patients were in the non-chemo group. Pneumonia-related hospitalization among the chemo group was four-fold higher (13.1% (n=13) vs 3.5%). Only one patient in each group had ICU admission. Six patients in the chemo group and 5 patients in the non-chemo group had outpatient pneumonia. Conclusions: In June 2021, the US FDA approved the use of PCV20 vaccination in adults based on trial data confirming tolerability and immunogenicity. Our study shows substantial increase in vaccination in cancer patients by switching to one dose of PCV20. Through our QI initiative, we offered vaccinations to all patients receiving anti-cancer therapy and identified a significant decrease in ICU admission rates (1.2%). Database studies have shown 4.7 to 15% hospitalization and 9 to 21% ICU admission rates in patients with cancer. The hospitalization rate was 13% in our chemo group. Efficacy studies on PCV20 are currently ongoing in the US, and our data are the first reported efficacy data, exclusively in cancer patients. The limitation of our study is the lack of a comparative cohort since PCV20 was offered to all treatment patients. We recommend that pneumococcal vaccination should be offered to all patients with cancer, especially those undergoing chemotherapy.