List 4 facts about vaccines in relation to viruses.

1. Vaccines work by stimulating the immune system to be able to recognize viruses in the case of having to encounter them

2. Viral diseases that are treated with vaccines (antiviral medications) include yellow fever, measles, mumps, and rubella, and influenza

3. They are injected into your bloodstream, and even after many years, they will come to your defense

4. T cells, or T-lymphocytes, are directly impacted by vaccines because they get a more enhanced capability of combating that particular virus