Apparently, without the "host" command, which is part of the bind-tools package, freshclam cannot query current.cvd.clamav.net This is the error it reports: ERROR: Can't query current.cvd.clamav.net WARNING: Invalid DNS reply. Falling back to HTTP mode. Emerging bind-tools fixes the problem. Shouldn't bind-tools be a dependency of clamav?
Nevermind. I was mistaken. Emerging bind-tools is not a fix.
Indeed, clamav doesn't use "host" command to resolve - see freshclam/dns.c in clamav tarball