Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1     Pharmacodynamic properties
Pharmacotherapeutic group: encephalitis vaccines, ATC Code: J07 BA01

The pharmacodynamic effect of the product consists of the induction of a sufficiently high concentration of anti-TBE antibody to provide protection against the TBE virus.

The protection rate of the previous generation and current TBE vaccine has been determined during a continuous surveillance as performed among the total Austrian population since 1984. In this surveillance a protection rate in children of above 98% after completion of the primary vaccination schedule (3 doses) was calculated for the period 1994 to 2003. Based on a follow up surveillance performed among the total Austrian population for the years 2000 to 2006, a protection rate of 99% was calculated with no statistically significant difference between age groups in regularly vaccinated persons.
The protection rate is at least as high after the first two vaccinations, following the conventional and rapid vaccination i.e., before completion of the basic vaccination scheme by the third vaccination.

In those with a record of irregular vaccination protection rate is significantly lower.

In clinical studies with TicoVac Junior 0.25 ml, seropositivity was defined as an ELISA value >126 VIE U/ml or NT titers 10. Pooled seropositivity rates determined by ELISA and NT at 21 days after the second and third vaccination in the conventional schedule are presented in Table 1 and Table 2.

Table 1.
Conventional immunization schedule, pooled seropositivity rates 1 as determined by ELISA and NT Subjects aged 1-5 years                                    ELISA2                               NT2 
Dose                             2nd                 3rd               2nd             3rd Seropositivity rate1,%                    99.4              100.0               98.5           99.5 (n/N)                       (501/504)             (493/493)      (196/199)          (193/194) Table 2.
Conventional immunization schedule, pooled seropositivity rates 1 as determined by ELISA and NT Subjects aged 6-15 years                                  ELISA2                                NT2 
Dose                          2nd                   3rd            2nd                 3rd Seropositivity rate1,%                 97.1                 99.8           95.5                99.7 
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Subjects aged 6-15 years                               ELISA2                           NT2 
Dose                         2nd                  3rd         2nd               3rd (n/N)                      (496/511)            (505/506)   (274/287)         (289/290) 1
- evaluated 21 days after each dose
2
- seropositivity cut-off: ELISA >126 VIE U/ml; NT ≥ 1:10

The highest seropositivity rates as determined by ELISA and NT were achieved upon administration of the third dose. Therefore, completion of the primary vaccination schedule of three doses is necessary to achieve protective antibody levels in almost all recipients.

5 months after the second vaccination more than 97% of children aged 1-5 years and more than 93% of children aged 6-15 years showed seropositive TBE antibody levels in both ELISA and NT.

Results from a follow-up study that investigated the persistence of TBE antibodies support the need for the first booster vaccination no later than three years after primary immunization. An analysis on seropersistence up to 58 months after the first booster showed high seropositivity rates in NT for all age subgroups: 96.6% in children aged 1-2 years, 100% in children aged 3-6 years and 98.1% in those aged 7-15 years, supporting a 5-year booster interval from the first booster onwards.

TicoVac vaccination induces statistically equivalent titers of TBE virus neutralizing antibodies against European, Siberian and Far Eastern TBE virus strains. In a published clinical study considerable cross- neutralising antibodies were also induced against Omsk Hemorrhagic Fever Virus, however titers were lower than against the TBE virus subtypes.

A study on the persistence of immune memory in individuals from the age of 6 years and older whose vaccination intervals were longer than recommended (≤12 years) showed that a single catch-up vaccination with TicoVac was able to elicit an anamnestic antibody response in 99% of children as measured by ELISA.
No data are available on antibody response as measured by NT.

Pharmacokinetic Properties

5.2        Pharmacokinetic properties

Not applicable.