function vaccine function YH, MC, XZ, and AR PERSPN: Oliver He: There has been hot discussion about whether we use 'vaccine function' or 'vaccine role'. Vaccine role may not be the good term to use. Vaccine is designed to be 'vaccine', so it should be vaccine function. One special case is cowpox virus. The cowpox virus can be mixed with some liquid like water and used as a smallpox vaccine. In this case, people often say: the cowpox virus has a 'vaccine role'. However, the cowpox virus vaccine is a processed material of a mix of the virus with water. The virus is a virus, it is not a vaccine per se. Therefore, vaccine role may not be an accurate term. vaccine function is a function that inheres in a vaccine that induces protective immune response against a disease. It is realized in the immunization process in the host. preventive vaccine function therapeutic vaccine function