The health workers were able to enter known Taliban hotspots in the south to vaccinate children as part of a drive to eradicate the crippling disease, WHO team leader Tahir Mir told AFP.
"We hired a lot of staff at a local level -- people from the same population, same tribe, same districts. They kept on trying to reach the anti-government elements.
"We tried to convince them this is for the children of Afghanistan -- it could be a Taliban child or a government child, to save them from this crippling disease. This time it looks like they were convinced."
Afghanistan is one of a handful of countries where polio is still present. There have been nine new cases this year, most in the south which sees regular fighting between Taliban forces and troops. There were 31 new cases last year.
The areas the teams reached included parts of southern Helmand and Kandahar provinces, which have seen some of the worst violence of the Taliban insurgency, and where the conservative Islamic rebels are de facto in control.
Among them was Musa Qala district, which has been Taliban control since early this year. Health workers immunised 50,000 children there, Mir said.
This round of vaccinations, involving about 10,000 health workers, started in the south on Wednesday and moves to the east, also troubled by violence, on Monday. The entire campaign aims to reach 1.48 million children.