Persistence of protective immunity following vaccination against tick-borne encephalitis--longer than expected?
A descriptive evaluation of protective immunity was performed on subjects with a complete primary tick-borne encephalitis (TBE) immunization (and additional regular boosters) more than 3 years after primary or booster TBE immunization, as measured by neutralization test and two different ELISA systems. The study population (n = 430) was stratified for age (i.e., 18-49 or 50 years of age) and for the number of years since last TBE vaccination. GMTs (NT) of all subgroups (at the time of the present evaluation) were above detection limit: 144 and 44 for the 18-49- and 50-year-old subjects, respectively. One percent of subjects aged 18-49 years, and 6% of subjects aged 50 years were ELISA-negative. A detailed sub analysis revealed that subjects with either low NT and/or negative to borderline ELISA test results are usually older and constitute a higher number of subjects without any TBE booster vaccination compared to the respective test-positive subject group. From the fourth year (exceeding 3 years after last vaccination) titers show a decline rate of 6-7%. This study indicates that after multiple TBE (booster) immunizations protection surpasses the currently advised TBE booster interval of 3 years, thus supporting reconsideration of the recommendations for booster intervals.
Rendi-Wagner
P
P
Department of Specific Prophylaxis and Tropical Medicine, Institute of Pathophysiology, University Vienna, Kinderspitalgasse 15, A-1095, Austria. joy.pamela.wagner@univie.ac.at
Kundi
M
M
Zent
O
O
Dvorak
G
G
Jaehnig
P
P
Holzmann
H
H
Mikolasek
A
A
Kollaritsch
H
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000032:analysis* / Q000096:biosynthesis; D004669:Encephalitis Viruses, Tick-Borne / Q000276:immunology*; D004675:Encephalitis, Tick-Borne / Q000276:immunology* / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D013997:Time Factors; D014611:Vaccination; D014765:Viral Vaccines / Q000276:immunology*
D000914:Antibodies, Viral; D014765:Viral Vaccines