This is the 5713th most frequent Korean word.
백신인
The term "백신인" does not exist as a standard word in Korean. It appears to combine "백신" (vaccine) with "인" (person), potentially meaning "vaccine person," but its exact definition depends on context.
In this sentence, '백신인' is used as an adjective describing '사람들' (people) to indicate that they are vaccinated.
백신인 사람들은 집단 면역을 형성한다.
People who received the vaccine form herd immunity.
Here, '백신인 것' functions as a noun clause implying the state of being vaccinated.
백신인 것이 꼭 필요하다.
Being vaccinated is absolutely necessary.
The phrase '백신인 상태' conveys the condition of being vaccinated and serves as a subject in this context.