Heavy rains kept parents away from the 6,400 pulse polio booths set up across the city on Sunday.
Only 8.3 lakh (63 per cent) of the 13.25 lakh children below five years were administered polio drops.
There was a low turnout at the last polio immunisation round in August too due to the swine flu scare. But even then, 66 per cent of the children had been covered.
“The response was not bad considering it was raining heavily in Bandra and other parts of the city,” said BMC’s immunisation in-charge Dr Mangala Gomare. She added that parents also avoid coming to the booths as they know the civic health care volunteers go door-to-door.
Parel fared the best with 75 per cent coverage while Bandra fared the worst with just 52 per cent.
The children were given the trivalent vaccine, which immunises against all strains of polio, as many cases of both the P1 and P3 strains have been detected in Uttar Pradesh and Bihar this year.
The drive was simultaneously held in the northern states, Mumbai and neighbouring districts like Mira-Bhayendar, Kalyan-Dombivli and Bhiwandi where migrants from UP and Bihar settle.
The BMC will continue the drive through the week to cover all children. Volunteers will go door-to-door, mobile teams will go to construction sites and transit teams will be set up at major railways stations till Friday.
Mumbai has been polio-free for over a year now. The last case was detected in Govandi in March 2008.