Delhi is seeing a sudden spurt in the number of polio cases among children there in spite of most of them already having received polio drops.
Delhi was free from polio cases for 21 months. Then came the case of eight month old Sameer who has never traveled out of Delhi and had already been administered polio drops four times.
His parents who had made sure that he got his polio vaccination made their shock evident when their son was diagnosed with the debilitating disease.
"Sameer was given polio drops four times, but even that has not helped. We are very worried," said Amjad Ali, Sameer's father.
Other cases of children being diagnosed with polio included three other in Delhi who had also been given polio drops several times. One-year-old Shivinder came with his parents from Mainpuri in Uttar Pradesh, one-year-old Jannat came from Bihar and two-year-old Ashraf's family came from Jaipur.
The Delhi government has alleged that the infection is being brought in from outside.
P K Hota, Union Health Secretary said, "It's a setback for us. The infection has come from western Uttar Pradesh where there have been many cases, and because of high mobility, they carry the infection here."
Last year there were 66 new polio cases across India and this rose to 416 cases in 2006. The government has called it an outbreak.
According to experts the oral polio vaccine isn't 100 per cent effective, so some children can get it despite immunization and cases of children who have got the infection in spite of taking the oral vaccine is an index of the failure of the immunization drive.
They go on to say that children get left behind in each drive and therefore the virus remains in the environment and continues to infect other children. As a result even if a child has been administered the polio drops, he may still not be immunized.