Once upon a time, "life" was defined as the ability to replicate, but no longer.
A virus is a complex, chemical compound, that has the ability to invade living cells and trigger these cells into replicating the virus. However, note that the actual virus compound did not self-replicate, it conned living cells into doing its bidding.
Think of it as a tweet on Twitter. The tweet cannot produce copies of itself. It relies on people to read it, then be conned into retweeting it. Thus a single tweet can end up with thousands of copies of itself being retweeted, as though it did have a life of its own.
Also, both the virus and the tweet can have a detrimental effect on their hosts.

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Come to think of the way that a virus spreads by conning its host, have you ever considered the bible???