Why are booster shots needed?

Related questions

1. Should seniors get measles vaccine?
2. Do adults need vaccine boosters?
3. Can a vaccinated child get measles?
4. What age do you get measles vaccine?
5. Can vaccines shed?
6. Does measles vaccine last forever?
7. How dangerous are measles?
8. How effective is the measles vaccine?
9. Is measles vaccine good for life?
10. Is a measles vaccine good for life?

Tags

1. #levels
2. #memory
3. #intended
4. #exposure
5. #increase
6. #antigen
7. #booster
8. #against
9. #declined
10. #after
11. #through
12. #injection
13. #initial
14. #immunizing
15. #immunization
16. #immunity
17. #protective