also: ブレークスルーかんせん
noun
breakthrough infection
Medical term for a COVID-19 or other vaccine-preventable disease infection occurring in a fully vaccinated person.
ワクチン接種後もブレイクスルー感染のリスクはゼロではない。
Even after vaccination, the risk of breakthrough infection is not zero.
彼は
He had two shots but got a breakthrough infection with mild symptoms.