Are nail varnish and nail gel allowed on nurses and doctors?

No.

Background:
The Robert Koch Institute, in agreement with other international organisations, recommends to compare gelled fingernails with painted fingernails and therefore prohibiting them in risk areas of hospitals and medical practices. People who treat and take care of patients should refrain from using non-transparent (coloured) nail varnish and gelled fingernails since contaminations are not visible and the necessary removal may not be carried out.