Pharmacotherapeutic group: pneumococcal vaccines, pneumococcus, purified polysaccharides antigen, ATC code: J07AL01
The vaccine is prepared from purified pneumococcal capsular polysaccharide antigens derived from the 23 serotypes that account for approximately 90% of invasive pneumococcal disease types. The following pneumococcal capsular polysaccharides are included: 1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19F, 19A, 20, 22F, 23F, 33F.
Immunogenicity
The presence of type-specific humoral antibodies is generally thought to be effective in preventing pneumococcal disease. A ≥2-fold increase in antibody level following vaccination was associated with efficacy in clinical trials of polyvalent pneumococcal polysaccharide vaccines. However, the concentration of anti-capsular antibody required to protect against pneumococcal infection caused by any specific capsular type has not been established. Most persons aged ≥2 years (85 to 95%) respond to vaccination by making antibody to most or all of the 23 pneumococcal polysaccharides in the vaccine. Bacterial capsular polysaccharides induce antibodies primarily by T-cell-independent mechanisms and elicit poor or inconsistent antibody responses in children aged <2 years.
Antibodies can be detected by the third week following vaccination but may decline as soon as 3 to 5 years after vaccination and a more rapid decline may occur in some groups (e.g., children and the elderly).
Immune responses to eight of the polysaccharides in Pneumococcal polysaccharide vaccine have been compared following administration of a single dose of vaccine or placebo. Four groups of subjects were entered as defined by age (50-64 years and ≥65 years) and by prior vaccination status (no prior vaccination or 1 vaccination 3-5 years previously).
o Prior to vaccination, antibody levels were higher in the revaccination group than in the primary vaccination group.
o In the primary and revaccination groups the geometric mean antibody levels for each serotype increased from pre- to post-vaccination.
o The ratios in geometric mean antibody concentrations by serotype at day 30 between those who were revaccinated and those who were given primary vaccination ranged from 0.60-0.94 in the ≥65 years group and from 0.62-0.97 for the group aged between 50-64 years.
The clinical relevance of the lower antibody responses observed on revaccination compared to primary vaccination is not known.
Concomitant administration
In a double-blind, controlled clinical trial, 473 adults, 60 years of age or older, were randomised to receive a single dose of ZOSTAVAX either concomitantly (N=237), or nonconcomitantly (N=236) with 23-valent Pneumococcal polysaccharide vaccine. At four weeks post-vaccination, the VZV-specific immune responses following concomitant use were not similar to the VZV-specific immune responses following nonconcomitant administration. However in a US effectiveness cohort study of 35,025 adults ≥60 years old, no increased risk of herpes zoster (HZ) was observed in individuals who received ZOSTAVAX and 23-valent pneumococcal polysaccharide vaccine concomitantly (N=16,532) as compared to individuals receiving ZOSTAVAX one month to one year after 23-valent pneumococcal polysaccharide vaccine (N=18,493) in routine practice. The adjusted hazard ratio comparing the incidence rate of HZ in the two groups was 1.04 (95% CI, 0.92, 1.16) over a median follow-up of 4.7 years. The data do not indicate that concomitant administration of the two vaccines alters the effectiveness of ZOSTAVAX.
Efficacy
The efficacy of polyvalent Pneumococcal polysaccharide vaccine was established for pneumococcal pneumonia and bacteraemia in randomised controlled trials that were conducted among novice gold miners in South Africa. The protective efficacy against pneumococcal pneumonia, the primary endpoint in these studies, was 76.1% with a 6-valent vaccine and 91.7% with a 12-valent preparation. In trials conducted in populations for which the vaccine is indicated (see section 4.1), vaccine effectiveness was reported to be 50 to 70% (e.g., persons with diabetes mellitus, chronic cardiac or pulmonary disease, and anatomic asplenia).
One study found that vaccination was significantly protective against invasive pneumococcal disease caused by several individual serotypes (e.g., 1, 3, 4, 8, 9V, and 14). For other serotypes, the number of cases detected in this study were too small to draw conclusions about serotype specific protection.
The results from one epidemiologic study suggest that vaccination may provide protection for at least 9 years after receipt of the initial dose of vaccine. Decreasing estimates of effectiveness have been reported with increasing interval after vaccination, particularly among the very elderly (persons aged ≥85 years).
The vaccine is not effective for the prevention of acute otitis media, sinusitis and other common upper respiratory tract infections.