Herd immunity occurs when enough people become immune to a disease to make its spread unlikely. As a result the entire community is protected even those who are not themselves.

Herd immunity occurs when enough people become immune to a disease to make its spread unlikely.As a result the entire community is protected even those who are not themselves. What percentage of a community needs to be immune in order to achieve herd immunity?

Vaccination is one of the best ways to create herd immunity.

Herd immunity varies from one disease to another disease as the source, effects and communicable ways are different. The disease that is more contagious will require a greater proportion of the population to be immune to stop its spread.

For example, the measles required 94% of the population to be immune to stop the spread chain.

relations between the soviet union and the united states were driven by a complex interplay of ideological, political, and economic factors, which led to shifts between cautious cooperation and often bitter superpower rivalry over the years. the distinct differences in the political systems of the two countries often prevented them from reaching a mutual understanding on key policy issues and even, as in the case of the cuban missile crisis, brought them to the brink of war.

the united states government was initially hostile to the soviet leaders for taking russia out of world war i and was opposed to a state ideologically based on communism. although the united states embarked on a famine relief program in the soviet union in the early 1920s and american businessmen established commercial ties there during the period of the new economic policy (1921–29), the two countries did not establish diplomatic relations until 1933. by that time, the totalitarian nature of joseph stalin's regime presented an insurmountable obstacle to friendly relations with the west. although world war ii brought the two countries into alliance, based on the common aim of defeating nazi germany, the soviet union's aggressive, antidemocratic policy toward eastern europe had created tensions even before the war ended.