Introduction
YFV, JEV infections, TBEV, Yellow fever
VIRUS, YELLOW FEVER, JAPANESE ENCEPHALITIS, TICK-BORNE ENCEPHALITIS, BLOOD
Yellow fever virus (YFV), tick-borne encephalitis virus (TBEV), and Japanese encephalitis virus (JEV) all belong to the The vaccine regimen and outcome of vaccinations against YFV, TBEV, and JEV infections differ significantly. After a single dose, the live attenuated YFV 17D vaccine provides at least 10 years, and possibly life-long, immunity [Safe and effective vaccine administration strategies are of significant importance [While the major endemic flaviviruses do not generally overlap in the world, they may affect travelers visiting these areas with need for protection. Accordingly, simultaneous vaccination with different vaccines including flavivirus not seldom vaccines occurs. It saves time and visits to health care units and vaccine clinics. It provides protection against multiple pathogens in a shorter time-span. Vaccinations prior to travelling to endemic areas has been further emphasized more recently given that many present flavivirus endemic areas are increasing, in part due to changes in climate change and other possible factors [To this end, we carried out an open label, non-randomized clinical trial assessing the safety and immunogenicity of concomitant vaccination with different commonly used flavivirus vaccines. The clinical trial included healthy adult volunteers who were concomitantly vaccinated with TBEV and YFV vaccines, JEV and YFV vaccines, or with only one of the three respective vaccines. Half of the concomitantly vaccinated study participants received both vaccines in the same upper arm while the other half received the vaccines in different upper arms. Blood samples were taken before and at multiple time-points following vaccinations. Safety and immunological responses including nAbs were evaluated. Collectively, the study provides safety and immunogenicity outcomes following concomitant vaccination with different types of flavivirus vaccines. The studies can be used for forming guidelines for more flexible immunization regimens for pathogenic flaviviruses.