"The religious leaders were ... asking the people to give their children anti-polio drops in their sermons in the mosques in rural areas of Balochistan," said Syed Faisal Ahmed, co-ordinator of the local Emergency Operation Centre.
Pakistan is one of just three countries in the world, along with Afghanistan and Nigeria, that have endemic polio, a once-common childhood virus that can cause paralysis or death. Last year, govt reported a record low of 19 cases, Ahmed said, with only one of them in Balochistan province.
The new campaign follows the detection of the rare Type 2 strain of polio in sewage samples taken by the World Health Organisation in November, Ahmed said. The WHO reported the findings last week.
No cases of the Type 2 strain have been reported in humans in Quetta but it has been added to the vaccine as a precaution. The more common type of polio is Type 1, with no human cases of Type 2 reported for more than a decade.
"We have achieved major goals in combating polio disease, but still we have to strive more to declare country a polio-free country," Ahmed said.
Immunisation efforts have in the past been hampered by Islamist militants. Last January, a suicide bomber killed 15 people outside a vaccination centre in Quetta in an attack claimed by the Pakistani Taliban and another militant group, Jundullah.
Militants in Pakistan have previously alleged the immunisation campaigns are a cover for Western spies.