Meaning:
“加强” literally means “to boost, reinforce,” and “针”means “injection.” This term, translated as “a booster shot,” refers to an additional shot administered when a person has completed their vaccine series and protection against the virus has decreased over time. Additional doses are administered to people with moderately to severely compromised immune systems. For example, COVID vaccine booster shots are recommended for adults aged over 65, people with underlying medical conditions and those who work or live in high-risk settings.
Example:
A: 听说现在新冠疫苗可以打加强针了。
Tīngshuō xiànzài xīnguān yìmiáo kěyǐ dǎ jiāqiángzhēn le。
I’ve heard that the COVID vaccine booster shots are available now.
B: 是的，我四月份打完两针的，打算过几天就去社区健康中心咨询一下。
Shì de，wǒ sìyuèfèn dǎ wán liǎngzhēn de，dǎsuàn guò jǐtiān jiù qù shèqū jiànkāng zhōngxīn zīxún yīxià。
Yeah, I finished taking two jabs in April. Now I’m planning to ask about it at the community health center in a couple of days.