Alfred was quiet and seemingly depressed for a while after calicivirus vaccine, but the vet warned that he could feel unwell for a while. He also developed a sore at the injection site.
It’s good that he’s eating well, I think you shouldn’t be too worried but someone more knowledgeable than me will hopefully offer an opinion.

Vaccines challenge the immune-defense. That’s what they’re supposed to do: Trigger the body to start producing anti-bodies that will protect it against diseases.

But this process means the vaccinated bun – or person, or dog – can feel a bit under the weather for one to a few days after a vaccination. There can be a mild fever. That’s perfectly normal and just means the vaccine is starting to do what it’s supposed to.

It shouldn’t go on for more than a couple of days though, and if your bun stops eating or eats a lot less than normal, you should definitely contact your vet.