Virus neutralization
YFV, TBEV
Apart from the assessment of antigen-binding IgG responses, rapid fluorescence focus inhibition tests (RFFIT) were performed to measure nAb titers against TBEV, JEV, and YFV to compare the effect of concomitant vaccinations with respective single vaccination outcomes. All study participants were screened at day 0 for nAbs against the three flaviviruses. Two study participants had nAbs against TBEV at day 0 (one each from cohorts A1 and A2, respectively). These were excluded from subsequent analyses. No study participants had preexisting nAbs against JEV or YFV at day 0.Few study participants developed TBEV nAbs by day 30, however, the majority developed nAb titers by day 210 (30 days after third dose) (A1: 84%, A2: 95%, and C: 80%) (No statistical differences were observed in terms of nAb titers were observed when concomitant vaccinated study participants had received their respective vaccine in the same upper arm versus in different upper arms. A trend towards higher titers (mean value) of nAb was noted in the groups where vaccines were given in the same upper arm (cohorts A2 and B2) versus different upper arms (cohorts A1 and B1) (The design of the clinical trial also allowed us to divide the enrolled study participants based on gender. No statistically significant differences were observed between males and females in terms of final nAb titers against TBEV, JEV, or YFV (In summary, concomitant TBEV or JEV vaccination with YFV vaccine did not affect the development of virus-specific nAbs towards TBEV or JEV. Likewise, YFV nAb titers did not differ between the cohorts, whether the YFV vaccine was administered alone or together with the TBEV or JEV vaccines (