Berens-Riha et al.
Five accelerated schedules for the tick-borne encephalitis vaccine FSME-Immun® in last-minute travellers: an open-label, single-centre, randomized controlled pilot trial.
J Travel Med. 2023;taad053. doi:10.1093/jtm/taad053
Since 2011, the WHO recommends TBE vaccination for travelers who plan outdoor activities during their travel in endemic regions. The standard vaccination schedule does not meet the needs of last-minute travelers. Therefore, a single-center open-label randomized controlled pilot study has been carried out in TBE-naïve individuals (soldiers) aged 18 to 49 years to assess various accelerated/rapid vaccination schemes using the TBE vaccine FSME-Immun.
Group 1 received one intramuscular (IM) dose on day 0 and day 14 (classical accelerated schedule). Group 2 received 2 IM doses on day 0. Group 3 received 2 intradermal (ID) doses (1/5 of vaccine vial) at day 0. Group 4 received 2 ID doses on day 0 and on day 7. Group 5 received 2 ID doses on day 0 and on day 14. A last vaccine dose was applied one year either IM or ID vaccination.
All ID groups showed higher GMTs than the IM groups on days 14–28. Vaccination schedules with three vaccination visits showed higher titers than those with only two vaccination visits. Schedules with an interval of 14 days developed the highest titers. The double dose IM on day 0 showed a weaker response on day 28.
After day 28, antibody levels waned in all groups, but the last dose a year later showed an excellent booster response. The accelerated ID schedules might offer a better immunological alternative for last-minute travelers at risk. However, one would consider an aluminum-free vaccine to evaluate this vaccination route in formally powered non-inferiority trials.