Officials at the United Nations children’s body, Unicef, said Dr Rehman was the first doctor to be killed on duty.
His daughter, Zakira, told the Telegraph: “He regarded his duty as very sacred and always tried to reach the accessible population and convince them of vaccination.”
There was no immediate claim of responsibility for the shooting. The area is infested with militants and the Tehrik-e-Taliban Pakistan (TTP), an umbrella group of armed factions, has been waging a long-running insurgency targeting security forces and government officials.
Pakistan and neighbouring Afghanistan are the only two remaining countries where polio is endemic, after a 35-year global eradication campaign has cut cases to just a handful each year.
Six cases were detected in Afghanistan in 2023 and six in Pakistan. Neither country has reported a case so far in 2024.
The virus has proven frustratingly difficult to finish off in this part of the world, despite huge sums of money being spent and the regular mobilisation of armies of anti-polio workers.
Ranged against the campaign is a stubborn mix of suspicion, poverty and insecurity.
TTP militants have in the past ordered halts to vaccinations, but opposition has also been a rallying cry for many firebrand clerics and extremist groups in the region.
Accusations are rife that the drops are harmful, tainted with pork, or even a Western plot to sterilise Muslims, leading to boycotts and hostility.