boosters
boo-sters
noun
Extra vaccine doses to strengthen or prolong protection against disease.
"The government urged everyone to get their boosters."
noun
Devices or substances that increase power, force, or effectiveness of something.
"The rockets used solid fuel boosters for launch."
Thesaurus
Synonyms: admirer, protagonist, champion, friend, supporter, plugger, promoter, relay link, relay station, booster station, booster amplifier, relay transmitter