A randomized, triple-blinded, placebo-controlled clinical trial evaluating immune responses of Typhim Vi and PPSV23 vaccines in healthy adults: The PREP study

Rapid and early identification of emergent infections is essential for delivering prompt clinical care. To advance the development of algorithms for the clinical management of infection identification, we performed a vaccination clinical trial to investigate the potential of using vaccination as a model for studying mild inflammation responses associated with different infections (NCT05346302). We collected data at various time points over 4 weeks from blood samples, wearable devices, and questionnaires. Following a 2-week baseline period, 210 healthy participants, aged 18-40 years, were administered either a Pneumococcal Polysaccharide vaccine (PPSV23), Typhoid Vi Polysaccharide vaccine (Typhim Vi), or placebo. In longitudinal analyses of blood biomarkers, we found that CRP was significantly higher at 2 days postvaccination, whereas basophils, IL-10, IL-12p40, and MIG were significantly higher at 7 days post-vaccination in the PPSV23 group compared to both other groups (all p < 0.05). MIP-1 beta was significantly lower in the PPSV23 group than in the placebo group, while monocytes and MPV were significantly lower in the Typhim Vi group than in the placebo group at 7 days post-vaccination (all p < 0.05). The PPSV3 group showed a higher inflammatory profile, suggesting that PPSV23 induces a stronger immune response compared to Typhim Vi. The distinct immune responses induced by the two vaccines indicate the potential for utilizing vaccines as models for studying inflammation responses associated with different infectious pathogens.