This article analyses the depictions of immunity and immunological functions employed in proprietary medical advertising in British newspapers between 1890 and 1940. Using marketing copy to gain insights into the ways immunity was presented to the public and normalised outside of medical institutions and publications, I offer four main areas of discussion. First, I present an analysis of the ways advertisements evoked both natural and artificial immunity in their marketing copy, thereby affording us insights into the ways immunity was made palatable both to those supportive of and opposed to vaccinations. I then unpack the ways in which this advertising copy often emphasised immunity rather than the immunological, that is, presented immunity as resistance to infection achieved by purchasing particular brands, rather than as part of a defensive process taking place at a cellular level. Third, I examine the ways in which advertisements engaged with futurity and drew on a narrative of social exclusion that pitted created communities of the immune against the non-immune. Finally, I analyse the ways in which immunity was used to connect the biological and the psychological, looking particularly at the ways immunity against worry was sold to the public.