Five UK Ebola nurses and doctors are under investigation by regulators, Public Health England says.
They are looking into the screening of medics who flew back to England on 28 December after treating patients in Sierra Leone.
On this flight was Scottish nurse Pauline Cafferkey - who developed Ebola - and some of her colleagues.
Questions have arisen over the health assessments and protocols that were followed.
Media reports have suggested Ms Cafferkey may have had signs of Ebola before leaving Sierra Leone but regulators have not commented on this.
Public Health England said: "During our recent assessment of the screening of some returning healthcare workers at Heathrow on 28 December, information emerged which needed to be passed to the General Medical Council and the Nursing and Midwifery Council.