<p>A total of 3,060 children, 9–12 months-old were elected for an epidemiological studies reported elsewhere <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049828#pone.0049828-Collaborative1" target="_blank">[14]</a> and referred as “Primary Target Sample”. The Clinical Trial design is highlighted by dashed format. The study population enrolled in the present investigation was selected from the “Primary Target Sample” according to the PRNT results and comprise 30 PV-PRNT<sup>+</sup> and 10 PV-PRNT<sup>−</sup> individuals on each experimental arm (17DD and 17D-213/77), reaching a total of 80 volunteers. The current Immunological Study design is highlighted by solid format.</p
