The present invention relates to a product named 'immunogenic complex', which comprises an adjuvant characterized by solid particles of highly ordered nanostructured mesoporous silica, preferably, the silica SBA-15, and vaccinal antigens from distinct nature, encapsulated in this kind of adjuvant. The immunogenic complex of the present invention allows the presentation of the antigens that compose it to lymphocytes in a safe, gradual and sustained way, which leads to a more efficient immunological memory, increases the immunogenicity of the antigen and improves the production of antibodies. It ensures an efficient immunological protection with lower amounts of antigens and/or less repetition of vaccinal doses. In addition, the characteristics of the immunogenic complex of the present invention promote effective immunity induction, homogeneous in 'high and low responder' individuals.