Details of app-antivirus/clamav:

You must run freshclam manually to populate the virus database
before starting clamav for the first time.
This version of ClamAV provides separate OpenRC services
for clamd, freshclam, clamav-milter, and clamonacc. The
clamd service now starts only the clamd daemon itself. You
should add freshclam (and perhaps clamav-milter) to any
runlevels that previously contained clamd.

You must run freshclam manually to populate the virus database
before starting clamav for the first time.
This version of ClamAV provides separate OpenRC services
for clamd, freshclam, clamav-milter, and clamonacc. The
clamd service now starts only the clamd daemon itself. You
should add freshclam (and perhaps clamav-milter) to any
runlevels that previously contained clamd.

You must run freshclam manually to populate the virus database
before starting clamav for the first time.
This version of ClamAV provides separate OpenRC services
for clamd, freshclam, clamav-milter, and clamonacc. The
clamd service now starts only the clamd daemon itself. You
should add freshclam (and perhaps clamav-milter) to any
runlevels that previously contained clamd.

You must run freshclam manually to populate the virus database
before starting clamav for the first time.
This version of ClamAV provides separate OpenRC services
for clamd, freshclam, clamav-milter, and clamonacc. The
clamd service now starts only the clamd daemon itself. You
should add freshclam (and perhaps clamav-milter) to any
runlevels that previously contained clamd.

You must run freshclam manually to populate the virus database
before starting clamav for the first time.
This version of ClamAV provides separate OpenRC services
for clamd, freshclam, clamav-milter, and clamonacc. The
clamd service now starts only the clamd daemon itself. You
should add freshclam (and perhaps clamav-milter) to any
runlevels that previously contained clamd.

You must run freshclam manually to populate the virus database
before starting clamav for the first time.
This version of ClamAV provides separate OpenRC services
for clamd, freshclam, clamav-milter, and clamonacc. The
clamd service now starts only the clamd daemon itself. You
should add freshclam (and perhaps clamav-milter) to any
runlevels that previously contained clamd.

Test target not available when USE=libclamav-only is set, skipping tests ...
You must run freshclam manually to populate the virus database
before starting clamav for the first time.
This version of ClamAV provides separate OpenRC services
for clamd, freshclam, clamav-milter, and clamonacc. The
clamd service now starts only the clamd daemon itself. You
should add freshclam (and perhaps clamav-milter) to any
runlevels that previously contained clamd.