How are head lice spread?

Contact. Sharing combs, headgear or sleeping or lying on same furniture. It is common to spread within a classroom or within a household.Each person needs to be treated.
Close contact . Especially thru common use of a comb or brush or hat.
Head lice. Head lice are transmitted two ways. The most common is direct person to person contact. The second way is vector transmission – from a contaminated object to a person.