Torque Teno Virus Viral Load as a Predictive Marker of Serotype‐Specific Antibody Response Following the 13‐Valent Conjugated Pneumococcal Vaccine in Adult Kidney Transplant Recipients: A Cohort Study

Studies have shown that Torque teno virus (TTV) viral load predicts antibody response to SARS-CoV-2 mRNA vaccines in kidney transplant recipients (KTRs). However, its correlation with pneumococcal vaccine antibody response remains unknown. We enrolled KTRs receiving the 13-valent pneumococcal conjugate vaccine (PCV13). TTV viral load and 12 pneumococcal serotype-specific (PSS) IgG antibodies were measured at baseline. PSS IgG antibodies again 12 weeks post-vaccination. Vaccine responders were defined as those with a minimum two-fold increase in the geometric mean concentration across all 12 PSS IgG antibodies. Logistic regression was used to identify predictors of vaccine response, and receiver operating characteristic curve analysis assessed the diagnostic performance of TTV viral load. Among 65 vaccinated KTRs, 38% responded to the vaccine. TTV viral load was inversely associated with vaccine response (adjusted odds ratio: 0.64, 95% CI: 0.46-0.88, p = 0.006); no other variables were significantly associated. TTV viral load demonstrated modest diagnostic utility, with an area under the curve of 0.74 (95% CI: 0.61-0.84) and an optimal threshold of 4.71 log₁₀ copies/mL (sensitivity 60%, specificity 85%). These findings suggest that TTV viral load may serve as a predictor of PCV13 vaccine responsiveness and could help optimize immunization strategies in KTRs.