Respuesta :
Based on the graph you can see that after introduction of the vaccine in 1960 there was a sharp decline in US measles cases. Then over the 1960s as immunization numbers increased the measles cases in the US once again sharply declined and except for the occasional breakout remained at 0 or near zero for decades.
Answer:
The vaccine works.
Explanation:
As you can see in the graph when the vaccine was introduced into the public the measles cases started to drop, and as the shield effect started to increase, society was more and more protected agaisnt measles so the disease remained virtually unactive for decades.