Tick-borne Encephalitis, Vaccine
Conditions
Keywords
Elderly, Tick-borne Encephalitis, Vaccine
Brief summary
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.
Interventions
0.5 ml intramuscular injection scheduled in the two different arms
Sponsors
Region Örebro County
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Serological response to vaccination with TBE vaccine following primary vaccination | NT measured 1 months after 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. |
| Serological response to vaccination with TBE vaccine following the full vaccine scehdule | NT measured 1 months after vaccination | 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). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Cellular immunity in young and elderly ( immune cell expression) | Measured 7 days after vaccination | T and B cell populations (flow cytometry) 7 days after TBE vaccination |
| Cellular immunity in young and elderly ( cytokine production) | Measured 7 days after vaccination | Cytokine production ( Luminex) 7 days after TBE vaccination |
Countries
Sweden
Contacts
Primary ContactAnja Rosdahl
Outcome results
None listed