When self-interest comes at the expense of everyone around you, it becomes a form of neglect. I'm fairly certain that Nigerian cousin is educated and has easy access to information about how inoculations save lives. In fact, he should know that inoculations originated in Africa. Yet his need for self-promotion overrides the importance of community protection.
To characterize it as “slavery” is not only inaccurate—it’s deeply disrespectful to the diaspora whose ancestors endured actual slavery, and to those still suffering under real systems of bondage today.