booster shot vs recall dose

booster shot and recall dose both are nouns.

Word	Noun	Adjective	Verb	Adverb
booster shot	Yes	No	No	No
recall dose	Yes	No	No	No

As nouns, booster shot and recall dose are synonyms defined as:

booster shot and recall dose: an additional dose that makes sure the first dose was effective

Other synonyms of booster shot include booster, booster dose.

booster shot (noun)	recall dose (noun)
an additional dose that makes sure the first dose was effective	an additional dose that makes sure the first dose was effective