Vaccination involves the encounter of non-human biological matter and human bodies, recalibrating our susceptibility to illness and death. This boundary-crossing act has been caught in conflicting webs of moral significance, including the normalizing frameworks of public health governance and its corresponding forms of resistance. Focusing on smallpox vaccination in the British-ruled Straits Settlements (Singapore, Penang, and Malacca) between 1868 and 1926, we examine the recurrent features of contentions over vaccination from the tentative beginnings of the 1868 Vaccination Ordinance to the systematic extension of vaccination in the twentieth century. Engaging science and technology studies of non-human agency and social theories on security, we argue that such contentions demonstrate the limits of a power formation we call governing through contagion (GTC). GTC centralizes law and other technologies to normalize public health measures that combat contagious diseases, while dysconnecting populations by its strategies of control. Our history of smallpox vaccination reveals: i) GTC relies on the interconnectedness of human and non-human actors in protecting populations against viral threats, a process in which law is essential but does not necessarily drive vaccination or other strategies of control; and ii) resistance to GTC, in which law plays an integral role, reinforces inequalities and differentiated treatment, a process we term endemic inter/dysconnectedness.