Can my cat have an allergic reaction to a cat vaccine? - Advanced Animal Care
Can my cat have an allergic reaction to a cat vaccine? - The Waggin Train Veterinary Clinic
The short answer is, yes, they absolutely can. Anytime you put something foreign into the body of a living creature, there is a potential for a reaction to that said something foreign. Vaccines are no different. You're putting a modified form of a virus, or in some cases, bacteria, into that cat and sometimes their immune system might go overboard with its reactions towards that particular item. So yes, they can have reactions.
Can my cat have an allergic reaction to a cat vaccine? - Animal Hospital of Statesville
Technically, yes. Anybody, dog, cat, human can have allergic reactions to foods, medications, and vaccines. Thankfully, as time has gone on and science has progressed, there are much fewer vaccine reactions than there used to be. I would still consider it a relatively rare occurrence, but, yes, technically, your cat could. What I'd say is if you're coming to get your vaccinations done, ideally, try to schedule it when you might be around your cat for the rest of the day. If not, you might have somebody who could monitor the cat during that first several-hour window afterward to make sure that they're feeling okay and don't have any issues.
A reaction may also be considered pain or a little bit of swelling or something like that. And sometimes we'll see that, especially in tiny kittens. They may be a little sore after one of the vaccines, so you just want to watch for that sort of thing. It's not usually a big deal for them to be slightly off for the day or a bit quiet. I wouldn't call that a reaction. It's just a normal response to getting the vaccine and being here and being stressed. So it's possible, but it's typically not a huge deal.