Immunogenicity of PCV13 during Hospitalization soon after infection resolution: Vaccis study.

Vaccination against Streptococcus pneumoniae in high-risk patients is crucial and hospitalization is a valuable opportunity. Adult patients hospitalized (>48 hours) for various infectious conditions and eligible for 13-valent pneumococcal conjugate vaccination from April 2021 to 2023 were included. The primary endpoint was the vaccine response rate (VRR) at least one month after vaccination. Of the 725 potentially eligible patients, 143 were included in the study. The most common comorbidities were diabetes mellitus (47%) and chronic cardiovascular disease (42%). VRR was acceptable at 46%, with a lower geometric mean concentration (GMC) of IgG in non-responders than in responders (1.27 µg/mL vs. 9.49 µg/mL, p < 0.001). In the multivariate analysis, the strongest negative predictor of VRR was a Charlson score of >3 (OR: 0.23 [0.06-0.81], p = 0.022). Vaccination within 48 hours after apyrexia (OR: 6.25 [1.85-20], p = 0.004) and the presence of diabetes (OR: 2.70 [1.05-7.14], p = 0.039) were independently associated with a better VRR. Hospitalization for acute infection should not be viewed as a barrier to vaccination but as an opportunity for optimized pneumococcal prevention after a short delay of apyrexia and should not be routinely postponed.