PCV13, PCV15 or PCV20: Which vaccine is best for children in terms of immunogenicity?

Background:The new 15 and 20-valent pneumococcal conjugate vaccines (PCV15 and PCV20) have been marketed on the basis of immunogenicity criteria, one of them being a non-inferior response as compared with the 13-valent vaccine (PCV13).In the past, PCV13 was also authorized on the basis of the same criteria, using the 7-valent vaccine (PCV7) as a reference.Methods: Our aim was to compare the immunogenicity of these three vaccines in toddlers.Functional opsonophagocytotic activity (OPA) titre ratios measured in the same and different randomized trials were computed to assess the respective immunogenicity of these four products.Results: Results suggest that both PCV15 and PCV20 are less immunogenic than PCV13 for most common serotypes and that the two new vaccines induce a broadly similar response.The PCV7 vaccine was already slightly more immunogenic than PCV13 meaning that PCV15 and PCV20 compare poorly with PCV7.Results also point towards a reduced immunogenicity of the 2+1 dose schedule compared to the 3+1 dose schedule for PCV13, PCV15 and PCV20.