Streptococcus Pneumoniae

The French Public Health Council recommended pneumococcal vaccination combined strategy for all immunocompromised patients in 2012. This strategy consisted in conjugated 13-valent pneumococcal (PCV13) injection followed 2 months later by polysaccharide 23-valent (PPV23) vaccine injection. In 2024, Health authorities changed guidelines to recommend one injection of PREVENAR20 instead of the 2-vaccine scheme general practitioners are usually in charge of this vaccination. Conjugated pneumococcal vaccine enhances the immunogenicity of the polysaccharide vaccine. Acute leukemia and lymphoma are treated with multiple courses of chemotherapy, impairing the immune system and potentially the response to vaccination. These patients are more at risk for developing pneumococcal invasive diseases than the general population. However, efficacy of pneumococcal vaccination is poorly documented in this setting. We assume that 65% of the patients are non-responders to double compared to 45% for PCV20PREVENAR20 vaccination, according to their anti-pneumococcal immunoglobulin G (Ig) titers and the opsonophagocytic activity (OPA). To assess the immunogenicity of the pneumococcal vaccination combined strategy in adult population of acute leukemia and lymphoma, we will measure anti-pneumococcal serotype-specific IgG titers and OPA at different time-points after completion of the combined vaccine strategy. The primary objective is to assess the immunogenicity of pneumococcal vaccination combined strategy at 3 months after the PCV13 injection (corresponding to 1 month after the end of the combined strategy in cohort A) using Ig G titers and OPA, compared to 3 months post PREVENAR20 (cohort B). At different time points (day 0, 4 weeks post PCV13, and 4 weeks, 3-6 months and 9-12 months post PPV23 and in day 0, 4 weeks post PREVENAR20 and 3 months, 5-8 months and 11-14 months post PREVENAR20, the immunological response to vaccination will be monitored using specific-serotype IgG titers, OPA, and total anti-pneumococcal Ig. We will determine predictive factors of non-response to vaccination by comparing demographic data, biological data and treatment received lymphoma patients. The tolerance and safety of the vaccination strategy will also be assessed in this specific hematological population.

RACSMEI addresses the high burden of infectious diseases in low- and middle-income countries, including Cambodia, where limited surveillance and laboratory capacity often obscure etiologies and transmission dynamics. This knowledge gap hinders the design of effective prevention and control strategies. RACSMEI will improve understanding across multiple pathogens using a multidisciplinary One Health approach. We will answer key questions on burden, ecology, transmission and population immune status to inform targeted and culturally appropriate interventions. The project combines a nationally representative One Health survey, social-science methods, and multiplex, diverse diagnostics to efficiently test for 57 priority pathogens, including zoonotic and vector-borne agents, vaccine-preventable and elimination-targeted diseases, enteric, respiratory, and environmentally transmitted pathogens and selected neglected tropical diseases and parasites relevant to Cambodia. Mathematical modelling will reconstruct and forecast transmission dynamics and assess the potential impact of future public-health strategies. By integrating intersectoral data and innovative methods, RACSMEI will generate actionable evidence for public-health authorities, support precision One Health interventions, and help reduce disease burden in affected communities. The project also aims to ensure the transferability of methods and insights to other countries facing similar challenges.