What injection? I only deal in humans but I don’t know of any injection for scabies its usually a cream, for humans anyway. Are you sure it was scabies? Ive actually never heard of rabbits getting it but I know its mega contagious in humans, so much so that if a child has it the whole school gets treated I would imagine that the humans in your household would have it too if your buns did

“Scabies in rabbits, also known as sarcoptic mange, results from infestation with the mange mite Sarcoptes scabiei. These tiny parasites burrow into the rabbit’s skin, causing crusty lesions to form on different parts of the body.

Treatment consists of injections or oral administration of various dewormers. These include three ivermectin injections, each spaced two weeks apart.

Another common dewormer, moxidectin, is not as effective as eradicating scabies mites in rabbits. Doramectin, marketed under the trade name Dectomax, appears to get rid of mites permanently after two injections given at 10-day intervals.”

After treating your rabbit with the appropriate medication, it makes no sense to put him back in an environment still containing scabies mites. You must thoroughly clean and disinfect his cage or hutch, keeping the bunny elsewhere during the process. Ask your vet about miticide products you can use in your rabbit’s living quarters that won’t harm him. Boric acid is one possibility.

Scabies is zoonotic, meaning it spreads between species. Treat every rabbit in your household, even if they appear asymptomatic. You must also treat every dog and cat in your home, unless they are already on monthly heartworm or flea and tick preventives that also eradicate mites. Be careful and wear gloves when handling your rabbit — people are also vulnerable to scabies mites. ”

From Dr. Google.

Since your rabbits are free to roam your house, I’d think your whole house is considered infected.

“Clothing, bedding, etc. should be cleaned in very hot water. Carpets or upholstery should be vacuumed. Vacuum the entire house and discard the bag, just to be on the safe side. The carpet and upholstery can be cleaned and treated, if desired, with Microban X-590 or Steri-Fab.”

Take your rabbits outside while you clean your carpets. If you are using a disinfectant/mite killer, check the label and be sure it is safe before letting your rabbits loose in the house again. Their home-base/cage needs a thorough disinfecting too, as well as any blanket/toy they use.