title: Factors determining immunological response to vaccination against tick-borne encephalitis virus in older individuals.
abstract: We performed a cross-sectional study including 533 individuals (median age 61) from the highly TBE endemic Åland Islands in the archipelago between Sweden and Finland. Blood samples, questionnaires and vaccination records were obtained from all study participants. The aim was to investigate if there was any association between TBEV antibody titer and 12 health-related factors. Measurement of TBEV IgG antibodies was performed using two commercial ELISA assays (Enzygnost and Immunozym), and a third in-house rapid fluorescent focus inhibition test was used to measure TBEV neutralizing antibodies. The age of the individual and the number of vaccine doses were the two most important factors determining the immunological response to vaccination. The response to each vaccine dose declined linearly with increased age. A 35 year age difference corresponds to a vaccine dose increment from 3 to 4 to achieve the same immunological response. Participants previously vaccinated against other flaviviruses had lower odds of being seropositive for neutralizing TBEV antibodies on average, while participants with self-reported asthma had higher odds of being seropositive. By comparing the 3 serological assays we show that the Enzygnost and Immunozym assay differ due to choice of cutoffs, but not in overall accuracy.
authors: Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors: Pontus
authors: P
authors: Lindblom
authors: Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors: Peter
authors: P
authors: Wilhelmsson
authors: Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors: Linda
authors: L
authors: Fryland
authors: Division of Medical Services, Department of Microbiology, County Hospital Ryhov, Jönköping, Sweden.
authors: Andreas
authors: A
authors: Matussek
authors: Department of Infectious Diseases, County Hospital Kalmar, Kalmar, Sweden.
authors: Mats
authors: M
authors: Haglund
authors: Clinic of Infectious Diseases, Linköping University Hospital, Linköping, Sweden.
authors: Johanna
authors: J
authors: Sjöwall
authors: Public Health Agency of Sweden, Stockholm, Sweden.
authors: Sirkka
authors: S
authors: Vene
authors: Åland Central Hospital, Mariehamn, Åland, Finland.
authors: Dag
authors: D
authors: Nyman
authors: Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden; Clinic of Infectious Diseases, Linköping University Hospital, Linköping, Sweden.
authors: Pia
authors: P
authors: Forsberg
authors: Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden; Division of Medical Services, Department of Microbiology, County Hospital Ryhov, Jönköping, Sweden.
authors: Per-Eric
authors: PE
authors: Lindgren
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D003430:Cross-Sectional Studies; D004669:Encephalitis Viruses, Tick-Borne / Q000276:immunology*; D004675:Encephalitis, Tick-Borne / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control* / Q000635:transmission; D015981:Epidemiologic Factors; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007109:Immunity; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012737:Sex Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D014611:Vaccination; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D014765:Viral Vaccines