Well, there are already a lot of good thoughts posted here.

Toby and Lily are indoors, aren't they? Like Luna and Lily. I think I will have mine being annually vaccinated against the kind of diseases that you can bring with you from outside, on your clothes and shoes, such as respiratory viral diseases and panleukopenia.

Cats can only be infected with FeLV and rabies when there is a direct contact to an ill cat, so I think it's not necessary to vaccine against these diseases when a cat lives only indoors, at least not every year, especially since these vaccines are suspected to cause fibrosarcoma.

Luna has been vaccinated annually against FeLV so far, and she had developed a lump between her shoulders after her last shot which has been surgically removed last year. I agreed with my vet that the FeLV-shot has been necessary last year since I was going to adopt a new kitten (Lily). Well, Lily has been tested negative for FeLV meanwhile (and got her shot), so I will discuss with my vet wether further shots are necessary for Luna or not.

Lisa, I'm sorry to hear your Sash is FeLV-positive, and I think your vet made the right decision not to vaccine her anymore. Her immune system might have problems to deal with the vaccine and the result could be a break out of her disease.

Kirsten