This is the 4279th most frequent Japanese word.
免疫
Immunity.
In this sentence, '免疫' refers to the physiological immune system, an essential protective mechanism.
免疫は体を病気から守る仕組みです。
Immunity is the system that protects the body from illnesses.
Here, '免疫' indicates the specific state or effectiveness of an individual's immune system.
ストレスが多いと免疫が弱まる可能性があります。
When stressed, immunity might weaken.
In this sentence, '免疫' represents the concept of developed or acquired immunity through medical intervention.