Revaccination with pneumococcal conjugate vaccine five years after primary immunization improves immunity in patients with chronic lymphocytic leukemia

Abstract

Patients with chronic lymphocytic leukemia (CLL) have impaired response to vaccination, which calls for improved vaccination strategies. This study aimed to evaluate antibody persistence five years after pneumococcal vaccination and response to revaccination. Seventyfour CLL patients and 31 controls, all primary immunized with 13-valent conjugated pneumococcal vaccine (PCV13) or 23-valent polysaccharide vaccine (PPSV23), were included. Antibody persistence was assessed, followed by revaccination with PCV13 and a second revaccination with PCV13 or PPSV23. Serological protection (SP), defined as serum serotype specific IgG concentration ≥0.35 μg/mL for ≥70% of shared serotypes, did not differ significantly in CLL patients primary immunized with PCV13 or PPSV23 (RR 2.7 (95% CI 0.5-13.1)), but was lower in patients compared to controls (10% vs 32%; RR 0.3 (0.1-0.7)). Following revaccination with PCV13, serological response (SR), defined as ≥2–fold increase for ≥70% of shared serotypes, was 24% in patients primary immunized with PCV13 vs 12% with PPSV23 (RR 2.0 (0.6-6.9)). A second revaccination with PCV13 significantly improved SR while PPSV23 did not further improve immunity. Our findings suggest that repeated doses of a T-cell dependent pneumococcal vaccine improve protection in CLL patients. The study is registered at www.clinicaltrials.gov (NCT05316831).