Trivalent oral polio vaccine (tOPV) has been used to prevent the three types of the polio virus for 30 years. More than 95% of children have taken this vaccine provided for the nation’s expanded immunization program and polio was virtually put under control in the country in 2000.
However, tOPV will be out of service this year after bOPV and IPV are used.
The reason for the change is that a small proportion of children have still contracted polio though they were vaccinated. Although this risk is low with less than one case in every 10 million doses, the World Health Organization (WHO) has requested all countries to put aside type 2 polio vaccine tOPV and use an alternate vaccine to eradicate polio globally.
From May, infants will take three doses of bOPV when they are two to four months old. From September, children will also receive Quinvaxem and IPV vaccines when they turn five months old. If children have got one to three doses of bOPV from May to September, they will be inoculated with one dose of IPV to enhance their immunity against the polio virus type 2.
Currently wild poliovirus continues to exist in several countries in the Middle East, South Asia and Africa. Some countries which have put the disease under control have recorded individual cases due to the intrusion of the wild polio virus. Therefore, there remain risks that polio would recur if vaccines are not well administered.