The vaccines used in India to combat the virus are:

• Zero Polio: The dose is given to a baby immediately after birth. It only gives initial immunity to the child.

• Monovalent vaccine: This vaccine is used to combat wild poliovirus types 1 and 3.

• Trivalent vaccine: It is used for all the three strains of the poliovirus.

• Injectable Polio Vaccine (IPV): Unlike Oral Polio Vaccine, which is used in mass immunisation campaigns, the IPV is a more potent method of preventing the disease.

So which measure is the most effective? “There are logistical problem associated with the IPV, although it is of great help,” says Dr Panna Choudhury, national president, Indian Academy of Paediatrics. “There are two ways of keeping a check on this virus. First, monovalent vaccine should be given in affected areas and for individual protection the injectable polio vaccine should be taken,” adds Dr Choudhury. On the other hand, Dr Saroja Balan, senior consultant, neonatology, Apollo Hospital, believes that it is equally important to increase awareness among people and improve sanitation standards. “The coverage of the immunisation should be increased manifold and ensure that the awareness campaign is heightened,” she says.

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But why does P1 virus attack even after repeated vaccination? How many doses should be administered? Due to the highly contagious nature of the disease, even before the child is vaccinated there are chances of him or her contracting polio, even though the symptoms may manifest at a later stage.

... contd.