Is a virus a living being?

The answer depends on exactly how you define living being. And scientific views have changed over time. The critical point is that they appear to be inanimate when observed as structures outside of cells, once they do enter an appropriate host cell they start to show the very life-defining activities of replication and growth. This article provides an interesting look at the debate, and suggests that living or not living may not be a simple dichotomous categorisation.

Interestingly, even though biologists long favored the view that viruses were mere boxes of chemicals, they took advantage of viral activity in host cells to determine how nucleic acids code for proteins: indeed, modern molecular biology rests on a foundation of information gained through viruses.

https://www.scientificamerican.com/article/are-viruses-alive-2004/