We don't own cats so I cannot say if this actually works for them, but we do own a dog.  We had a cocker spaniel who lived to be 18 y/o (no vax ever) and we now own another cocker who was 13 in May of this year.  Again, no vax and a natural diet of raw bones and raw food as much as possible.  It's difficult in winter months to put out raw food because it freezes!

This should be helpful to pet owners tho.

https://www.farmersalmanac.com/natural-flea-remedies-21368