Failed to start clamd.service: Unit clamd.service not found

I have installed clamav and it's affiliated files (and clamtk). However, I keep getting the error message:

Failed to start clamd.service: Unit clamd.service not found.

I get the error when I run

sudo service clamd start

I have tried many different things but can't find any answer online. Any solutions?

I am using Ubuntu 18.04.

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