Meaning:
“突破” means “breakthrough,” and “感染” means “infection.” This term, translated from the English term “breakthrough infection,” refers to the detection of SARS-CoV-2 RNA or antigen in a respiratory specimen collected from a person at least 14 days after they have completed all recommended doses of a COVID-19 vaccine. This term has popped up in media reports and in daily life conversations since the highly contagious Delta variant has led to an increase in breakthrough infections among the fully vaccinated in many countries, including China and the United States.
Example:
A: 最近发生了多起突破感染的新冠肺炎病例，看来打了疫苗也不能完全放心啊。
Zuìjìn fāshēng le duōqǐ tūpò gǎnrǎn de xīnguān fèiyán bìnglì，kànlái dǎ le yìmiáo yě bùnéng wánquán fàngxīn a。
There have been many new breakthrough infections recently, and it seems that we cannot let our guard down even after receiving two shots of vaccines.
B: 是的，去室内公共场所要戴口罩。
Shì de，qù shìnèi gōnggòng chǎngsuǒ yào dàikǒuzhào。
True. We need to wear masks at indoor public venues.