Help with distemper shot questions

Hi All!

Long time reader but needed to ask for some advice/reassurance as googling will drive me crazy and ive always trusted the people of these forums.

My cat is aprox. 11-12, not sure because I rescued him off the street probably 10 years ago, he has been very healthy for the most part (knock on wood) with the exception of his heart murmur, which has not gotten worse since they told me he had one years ago. 

I make it a point to address any concern or need as soon as possible with the vet if anything should happen and I take him for yearly checkups and he gets the rabies shot but ive always held off on the distemper but for whatever reason today the vet seemed to be extremely pushy  to get it and I caved in, they said everything ive heard that if he gets out (which he never does) or is around other cats even by a window its something you should get just so you dont regret not getting it. I've never believed in all these medicines but im also not crazy against them like some people are because it would honestly just drive me crazy.  They said because he hasn't got it and of his age, to get one now and then come back in 4 weeks for the booster. 

Ive beat myself up for getting it all day now because ive always held off on it because of things ive heard but just need someone to make me feel ok with my decision, I know nothing can be changed now at this point . Ive always been on top of everything and want to do the right thing and sometimes you just want to trust the vet and what they say/recommend but sometimes I just think, well I know,  they also need to make money. 

The cat has been fine, hes eating playing, running around and is himself but again, I just need to get it off my mind.

Also I see some people have said its ok for the one but dont go and get the booster in a few weeks, I think im just going to leave it at this one and cancel the remaining shot because of how I feel. I tend to over worry about EVERYTHING and for whatever reason this has been driving me crazy.  

Any advice please and thank you. 

There is no reason to get another one in 4 weeks.  That is only done with kittens.  The reason for it with kittens is that they still have some residual immunity from the mother.  It wears off slowly.  Though they don't have enough to protect them from distemper it is enough to keep the vaccine from taking full long term effect.  An adult cat doesn't have that residual immunity so the one shot will take full effect.

Thank you, it upsets me that they would feel the need to have the cat come back for a 2nd shot at this age...

The parvo ("distemper") virus is very hardy and something you can bring into your home on your shoes/clothing. It's a real killer of kittens, but elderly cats are also vulnerable.

When our shelter gets a stray cat whose vaccination history is unknown (as opposed to a cat whose shots simply aren't up to date), both distemper (panleukopenia) shots are given regardless of age. If it were my own cat, I'd get both shots; seeing a cat die of panleukopenia is gut-wrenching.