| Name | Description |
| Antigen | A foreign substance that elicits an immune response. |
| Co-infection | Simultaneous infection of a host by multiple strains. |
| Cross immunity | A partial immune protection against a strain. If two parallel strains of a virus are circulating in a population, then individuals who have already been infected by one strain may have partial immunity or lessened susceptibility to the other strain. |
| Herd immunity | Resistance of the entire population to the spread of an infectious disease due to the immunity of a high proportion of that population. |
| Super infection | The process of a strain taking over a host already infected by a different strain. In general, it refers to those affected with one of the strains that cannot be infected with others. |
| Perfect vaccine | A vaccine uniformly and completely effective against all strains of a pathogen. It further signifies vaccines that can be treated as a complete safeguard against the targeted strains. |
| IDM | Intermediate defense measure |
| PDS | Primary disease strain |
| SDS | Secondary disease strain |
| EGT | Evolutionary Game Theory |
| DFE | Disease Free Equilibrium |
| EE | Endemic Equilibrium |