Vaccinating kitten older than 16 weeks??

I am pondering adopting an adorable kitten that is older than 16 weeks and has not been with mum for quite some time. I do have 5 senior indoor cats that are also rescues, and latent URI etc. is possible so I have to vaccinate the kitten before I would take him home (just doing the main vaccine for URI etc.). One of my cats is a bit of a snuffler, but when he was younger, my other (young at the time) cats joined him, and there were no issues at all with the others catching anything (they were vaccinated).

What is the protocol for vaccinating a cat older than 16 weeks? I am generally of the less-is-more protocol for vaccines, and have read that if they are older than 16 weeks, they should be able to develop proper immunity from one vaccine shot (I sort of figured out - I think - that the series of shots are for when the kitten is younger than this?? correct me if I am wrong please). Secondly, how long does it take the vaccine to have effect and immunity to be provided? 1 week? 2 weeks? I will be talking to my vet but I was curious to find out different opinions from people on there.

This kitten does not stand much chance of living a full life in his current situation (he is in the countryside at a location where most cats get eaten by coyotes within their first year). So I would really love to give him a safe loving home where he can have a happy full life and I can enjoy his cute personality.

Thank you very much in advance!!

He should start his kitten shots as soon as possible, either before you bring him home or as soon as you can get him to the vet.  I like for my kitties to have all their kitten shots, then go by the less is better principle after that.  Once they've gotten the kitten shots and rabies vaccination, they're pretty much set for life if they remain indoors.  Oh, and keep him separated from your other kitties until you've gotten him to the vet to begin his shots and have him tested for the "nasties" (worms, fleas, etc.).

I was thinking of getting the first shot and second dewormer (he has been dewormed once) before I even take him home. He is safe enough for now where he is, so I can leave him there while the shot takes effect. Would he need a booster a few weeks later if he is older than 16 weeks? And would it be okay to take him home once the 1st shot has taken effect? This is what I am pondering.

Yes, he'll need all his boosters even though he's older than 16 wks, especially since he's not already had them.

There are a series of online interviews between Dr. Becker and Dr. Schultz that suggest that one vaccine shot after 16 weeks should provide enough immunity, without requiring booster shots.  To verify the immunity, a titer test can be done later. 

Dr. Pierson at catinfo.org discusses the various types of vaccines, giving recommendations for all shots. 

I have never seen it discussed how long after the shot is given that it officially takes effect.  You could always bring the kitty home and keep him in a separate room from the other cats.  Although I think I've read that some of the viruses (if present) can live for awhile on carpet/furniture...so you wouldn't want your other cats to go in that room for awhile, even after the kitty is free to roam the house. 

My youngest had her first shot shortly before 16 weeks, so she got a second shot a few weeks later.  We do not live in an area that requires rabies, and with no threat, she did not get that shot.  I don't foresee a booster in her future, she's indoors only.  We can always do the titer. 

Enjoy!

Thank you all. BTW I did find that article with those vets who suggest that one shot after week 16 is enough so that is what got me thinking as everything else was saying multiple shots - I could not get a feel for if the multiple shots are to ensure one has no unprotected period between mum's antibodies and vaccine, or if multiple shots were needed to get full immunity - you read something different everywhere you turn.

I have to say that I have five 15-year old cats who have not been over-vaccinated at all (in consultation with my vet) and not one of them has a hint of a kidney issue. I do wonder about that connection between over-vaccination and kidney inflammation etc.

I meant to say that booster shot or not, when could I introduce this kitten to my other kitties? As I said, my concern is that one of my cats is a "snuffler" (probably damaged sinuses etc. from when he had a URI as a kitten before I got him). My other cats were introduced to him at young ages and no one picked it up - so while this bodes well, there is a risk of him being contagious and kitty needs to be vaccinated/protected.

I just cannot find information as to *how soon the vaccination(s) begin to take effect* such that he has enough immunity to introduce him to my other cats. I get worried about leaving him at the place where he is (at a recreational facility in the country) once I start vaccinating him as someone else may clue in that his medical care is being paid for and take him just when I am starting to form attachment. But I also don't want to shove him alone in a quarantined room for a month as he does have feline friends where he is now - better to leave him where he is while the shots take effect than do that. I am going out of town in about a month for 5 days so that is another glitch in the timing of things.

I may just have to give up on this, as it is all so complicated.