In recent years, the health status of people living in developing countries has improved significantly. But this does not apply to everybody. The health inequality gap in developing countries and even in developed countries between people who can derive benefit and those who cannot has widened. And there is nothing more evident than inequality in the health of children. We cannot ignore the current situation in which depending on where a child is born, child mortality can be more than ten times that of other regions. Through my research so far, I think that vaccines are the most equitable health measure. The people who benefit most from vaccines are the poor.