There are over 100 strains of pneumococco (Streptococcus pneumoniae) which can affect children, especially in the first two years of age. Among them, serotypes 22F, 33F and 3 pose a danger to the youngest and are responsible for more than a quarter of all cases of invasive pneumococcal disease occurring under 5 years. The vaccine available today – 13-valent (PCV13) – offers coverage against 13 serotypes including 3, but not against 22F and 33F. Hence the search for new vaccines. The latest data on this front come from two clinical studies, PNEU-PED and PNEU-LINK, which evaluated the immunogenicity, safety and tolerability in neonates of a new 15-valent conjugate vaccine, which also includes 22F and 33F. The vaccine was approved in the US in July for adults over the age of 18.
Invasive diseases caused by pneumococcus
The disease is called invasive when the bacterium enters the bloodstream, causing serious illnesses that can even lead to death. Pneumococcus is in fact one of the main causes of sepsis and meningitis. It can also cause other conditions, including pneumonia and otitis. The people at greatest risk of invasive disease are children aged 0 to 5 and those over 64.
The results of the studies
The PNEU-PED study involved over 1,700 infants (aged 42-90 days) who randomly received 4 doses (at 2, 4, 6 and 12-15 months of age) of the pneumococcal conjugate vaccine 15- valent or licensed 13-valent pneumococcal conjugate vaccine. The results have just been announced by the pharmaceutical company MSD that produces it: the safety profile of the new vaccine was generally comparable to that of PCV13 after the administration of each dose; 30 days after the third dose demonstrated non-inferiority to PCV13 for all 13 shared serotypes based on serotype-specific response rates (proportion of individuals reaching the accepted immunoglobulin G cutoff value of 0.35 mcg / mL ), and for 12 of the 13 shared serotypes based on geometric mean serotype-specific IgG concentrations. This difference was no longer detected 30 days after the fourth dose. Immune responses were also statistically superior for the 15-valent vaccine compared to PCV13 for serotype 3, present in both vaccines, and compared to the predetermined values for serotypes 22F and 33F. The tolerability and safety of the new prophylaxis were confirmed by the PNEU-LINK study, conducted on 2,400 newborns. The data – the company said – will soon be presented at a scientific conference and used to request the extension of the approval to the regulatory authorities.
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