Primary TBE Vaccination for the Elderly

Study Overview
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Brief Summary
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Tick-borne Encephalitis (TBE) can be prevented by vaccine. Vaccine failure, defined as a case of TBE regardless of previous vaccination, has been described and seems to be more predominant with increasing age, suggesting a less effective immune response following with increasing age. In fact previous studies has shown a reduced antibody response in elderly individuals compared to younger when vaccinated against TBE. As a result, in Sweden, an extra vaccine dose has been recommended during the primary vaccine schedule to individuals > 50 years of age. This alternative vaccine schedule has not been tested. The investigator aim to test if an extra vaccine dose in the primary vaccine schedule for those > 50 years of age improves the immune response and offers a corresponding immunity to younger individuals following TBE vaccination.

Official Title
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Primary TBE Vaccination for the Elderly

Conditions
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Vaccine, Tick-borne Encephalitis

Intervention / Treatment
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* Drug: FSME-IMMUN Vaccine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults ≥ 50 years or between 18-40 years Man or woman God health Written informed consent Exclusion Criteria: Previous vaccination against TBE Previous TBE infection Allergy or hypersensitivity to any substance in the vaccine Previously known or suspected infection with Japanese encephalitis, Dengue virus, West Nile fever or Yellow fever Information on previous vaccination against Yellow fever or Japanese encephalitis Acute illness, eg fever with malaise Immunosuppression, due to medication or disease Previous treatment with Rituximab or equivalent Autoimmune disease, including diabetes (diet or tablet-treated diabetes with good metabolic control is accepted, HbA1c < 6 %) Obesity, BMI > 40 Moderate to severe renal failure including hemodialysis, estimated GFR < 30. Blood transfusion or immunoglobulins <3 months ago Pregnancy Any other illness where the investigator consider the subject unsuitable for the study The study subject does not want to participate

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: > 50 years<br>Healthy individuals > 50 years of age divided into age groups 50-59 years, 60-69 years and >70 years, approximately 20 participants in each group. Vaccinated with 4 doses FSME immune Adult intramuscular injection according to the recommended primary vaccine Schedule in Sweden for individuals > 50 years of age, at time 0, 1, 2 and 7 months. | Drug: FSME-IMMUN Vaccine<br>* 0.5 ml intramuscular injection scheduled in the two different arms<br>|
| Active Comparator: < 40 years<br>Healthy individuals < 40 years of age. Vaccinated with 3 doses FSME immune Adult intramuscular injection according to the standard recommended primary vaccine at time 0, 1, and 7 months. | Drug: FSME-IMMUN Vaccine<br>* 0.5 ml intramuscular injection scheduled in the two different arms<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Serological response to vaccination with TBE vaccine following primary vaccination | The proportion of individuals > 50 years that achieves protective levels following the extra primary vaccine dose compared to the proportion of individuals tha achieve protective levels of neutralizing antibodies following the second vaccine dose in those < 40 years. | NT measured 1 months after vaccination | 
| Serological response to vaccination with TBE vaccine following the full vaccine scehdule | The proportion of individuals > 50 years that achieves protective levels of neutralizing antibodies following the final primary schedule ( dose 4), compared to those < 40 years ( 3 doses). | NT measured 1 months after vaccination | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cellular immunity in young and elderly ( immune cell expression) | T and B cell populations (flow cytometry) 7 days after TBE vaccination | Measured 7 days after vaccination | 
| Cellular immunity in young and elderly ( cytokine production) | Cytokine production ( Luminex) 7 days after TBE vaccination | Measured 7 days after vaccination | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Elderly, Tick-borne Encephalitis, Vaccine