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Persistence of immunity to tick‐borne encephalitis after vaccination and natural infection
Author(s) -
Baldovin Tatjana,
Mel Rosanna,
Bertoncello Chiara,
Carpenè Graziella,
Soppelsa Fabio,
Giliberti Aurore,
Baldo Vincenzo
Publication year - 2012
Publication title -
journal of medical virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 121
eISSN - 1096-9071
pISSN - 0146-6615
DOI - 10.1002/jmv.23313
Subject(s) - medicine , vaccination , booster dose , immunity , tick borne encephalitis , persistence (discontinuity) , immunization , encephalitis , cohort , antibody , immunology , pediatrics , immune system , virus , geotechnical engineering , engineering
Long‐term persistence of immunity was assessed in 66 patients who had contracted tick‐borne encephalitis (TBE) and in 126 subjects who had completed primary TBE immunization using a conventional three‐dose schedule from 3 to 8 years earlier. Immunity was tested in the subjects stratified by age as follows: ≤40 years (N = 37); 41–60 years (N = 100); and over 60 years (N = 55). Antibody levels decreased significantly with increasing age in the vaccinated cohort by comparison with the individuals who had previously contracted TBE. Consistently higher geometric mean antibody levels were found in the patients infected naturally. When the vaccinated subjects were compared, subjects ≤40 years old had significantly higher antibody levels than either of the older groups. Analyzing immunity to TBE over time revealed a remarkable (50%) decline in seroprotection rates in the vaccinated group at 50 months of follow‐up, while stable, high levels persisted in all subjects after natural TBE infection. In the vaccinees over 60 years old, the TBE antibody levels reached 60% at 60 months, and 20% at 70 months of follow‐up; in contrast, in the 41–60‐year‐old group, the antibody levels remained high for 70 months, and then fell rapidly. For people aged <60 years old, booster doses are recommended every 5 years after the fourth dose of vaccine, which should be administered 3 years after primary immunization. In subjects aged 60 years or older, booster doses should be given every 3 years. J. Med. Virol. 84: 1274–1278, 2012. © 2012 Wiley Periodicals, Inc.