A cohort study was conducted in South Africa to address this issue: it reported that after neonatal BCG vaccination, there was no difference in the magnitude and profile of cytokine expression of BCG-specific CD4+ and CD8+ T cells between infants supposed to be protected (infants who did not develop TB disease despite exposure to TB in the household) and those supposed to be unprotected (infants who had developed culture-positive TB) after 2 years follow up [39]. The gene discussed is CD8A; the disease is tuberculosis.