The present invention is related with the pharmaceutical industry and the biotechnology, specifically with vaccine antigens applied against bacterial, viral, cancerous or another origin diseases. Development of pharmaceuticals formulations able to protect or to increase the protective spectrum of already developed vaccines and to extend it against several pathogens, using as target for the immune response, carbohydrates composed of repeated units of (α 2-8) linked N-replaced neuraminic acid. Several peptides were isolated and identified as molecular mimetics of the capsular polysaccharide form serogroup B of Neisseria meningitidis, which is composed of repeated units of (α 2-8) linked N-acetyl neuraminic acid. The immunogenicity of peptides was evaluated in animal biomodels, demonstrating their value as antigens able to induce the production of antibodies able of specifically recognize the bacterium N. meningitidis from serogroup B and of showing bactericidal activity against the same one. The resulting formulations of are applicable in the pharmaceutical industry as vaccine formulations for human use.