Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1 Pharmacodynamic properties

Pharmacotherapeutic group: Typhoid vaccines, ATC code: J07AP03 This vaccine contains purified Vi capsular polysaccharide of Salmonella typhi (Ty 2 strain). Immunity appears within 1-3 weeks after injection and lasts around 3 years.
A double-blind, randomized, controlled efficacy clinical trial was conducted in a highly endemic area in Nepal, in both paediatric and adult populations. A total of 3,457 subjects received TYPHIM Vi. The level of protection conferred by a single dose of the vaccine was 74% against blood culture-confirmed cases of typhoid fever throughout the 20 months of active surveillance when compared with the control group.
Seroconversion rate (defined as 4-fold rise of anti-Vi antibody levels) was collected in 19 clinical trials. These trials were conducted in endemic and non-endemic areas in both paediatric and adult populations representing a total of 2,137 evaluable subjects.
In adult population, seroconversion rate ranged from 62.5% to 100% four weeks after a single injection, with similar magnitude of anti-Vi immune response in non- endemic areas compared to endemic areas.
Anti-Vi antibody persistence depends on endemicity, with a trend for better persistence in endemic areas (documented up to 10 years in 83 children at levels equal or above serological correlate of protection of 1 µg/mL). In non-endemic areas, anti-Vi antibodies persist for 2 to 3 years. Revaccination should be carried out with an interval of not more than 3 years in subjects who remain at risk of exposure to typhoid fever.

Paediatric population
In a double-blind, randomized, controlled efficacy clinical trial conducted in a highly endemic area in South Africa, a total of 5,692 paediatric subjects from 5 to 15 years of age received TYPHIM Vi. The level of protection conferred by a single dose of the vaccine was 55% against blood culture- confirmed cases of typhoid fever during the 3- year follow-up period when compared with the control group.
Immunogenicity was assessed in both endemic and non-endemic areas in paediatric population aged from 2 to 17 years. In 9 clinical trials representing a total of 733 evaluable children four weeks after a single injection of TYPHIM Vi, seroconversion rate ranged from 67% to 100%, demonstrating similar magnitude of anti-Vi immune response to what was documented with adult participants

Pharmacokinetic Properties

5.2 Pharmacokinetic properties
Not applicable.