How Old Does A Kitten Have To Be To Wear A Flea Collar??

i have a kitten that is about 2 weeks old. the front of her neck looks like it has fleas, but they are very small and she does not seem to be bothered by them, besides they are only on the front side of her neck. do i need to get rid of these? or can i just put some medicine on them so she doesnt have anymore problems with them??

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