This is the 434th most frequent Japanese word.
感染
"感染" means "infection."
In this sentence, "感染" is used as a noun to describe the condition of being infected with a virus.
ウイルスに感染してしまった。
I became infected with a virus.
Here, "感染" refers to the potential spread or acquisition of a disease, emphasizing prevention.
彼女は感染のリスクを避けるためマスクをした。
She wore a mask to avoid the risk of infection.
"感染" is used metaphorically to describe a computer system being compromised by malicious software.