Across
- 1. Infectious disease caused by a virus that can cause paralysis
- 3. Infectious agent that can multiply in living cell
- 6. Enough of the population has either been vaccinated or gained immunity through natural infection to stifle the virus’s spread
- 7. illness
Down
- 2. When the body is resistant to disease
- 3. A substance injected to stimulate the production of antibodies
- 4. Contains dead or inactive
- 5. Chemical made by blood cells to attack pathogens