Primary TBE Vaccination for the Elderly

Region Örebro County90 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Enrollment

Conditions

Tick-borne Encephalitis Vaccine

Interventions

Eligibility

Sex: ALLMin age: 18 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

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.

Time frame: 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).

Time frame: NT measured 1 months after vaccination

Secondary Outcomes

Cellular immunity in young and elderly ( immune cell expression)

T and B cell populations (flow cytometry) 7 days after TBE vaccination

Time frame: Measured 7 days after vaccination

Cellular immunity in young and elderly ( cytokine production)

Cytokine production ( Luminex) 7 days after TBE vaccination