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You can see your vet and get some Frontline. The kittens are so small that their dose will need to be administered by a vet but it can be done. You need to take care of this quickly because newborn kittens can quickly become anemic and die when they have fleas.
Let me know if you still have questions.
Treating them is much safer than not treating and having them die from the anemia that comes as a result of the fleas. Treatment provided by your vet is much safer than buying an over the counter product.