A member of an anti-polio vaccination team worker was gunned down in Khyber Agency on Wednesday, DawnNews reported.
The incident took place in Jamrud Tehsil where unidentified gunmen fired shots at a polio vaccinator, sources said.
The injured worker, Fazal Amin, was shifted in critical condition to Hayatabad Medical Complex where he succumbed to his injuries.
A policeman was killed and two others suffered injuries when an explosion hit a police party providing security to a polio vaccination team near Peshawar on Tuesday.
Polio vaccination drives are underway across Pakistan, one of only two polio endemic countries left in the world.
Last year, the number of polio cases recorded in Pakistan soared to 306, the highest in 14 years. Pakistan has, however, witnessed a 62 per cent drop in polio cases in 2016, according to the Ministry of National Health Services (NHS).
Attempts to eradicate polio have been badly hit by militant attacks on immunisation teams due to claims propagated by the Taliban that the vaccination drive is a front for espionage or a conspiracy to sterilise Muslims.
These rumours have also made inhabitants of lesser-developed parts of the country more wary of allowing immunisation.
The Taliban stepped up attacks targeting polio immunisation teams after Pakistani doctor Shakeel Afridi was recruited by the Central Intelligence Agency to set up a hepatitis immunisation drive as part of efforts to track down Al Qaeda chief Osama Bin Laden.