A pediatrician I know wore a wig while doing her hospital based training (residency). The wig wearing doctor was woken to care for a baby in crisis and came to the intensive care ward with her head covered with her sleep teichel (scarf). By the time the baby was stable, it was time for rounds.
At the time the “premie” intensive care ward was run by a brilliant specialist (who was a bit of a tyrant in an effort to keep these babies alive). She sees the resident and stares at her for a bit too long and then said in effect “See how Dr. R is dressed. Keeping her hair covered like that! Hair is a vector for bacterial transmission! It would be best if everyone’s hair is kept up and ideally covered. Good work Dr. R”