Union Health and Family Welfare Minister Ghulam Nabi Azad on Sunday launched the bivalent oral vaccine against polio in Delhi and Uttar Pradesh to mark the national immunisation day.

The vaccine was launched in Bihar last month and offers protection from the P1 and P3 types of polio strains.

Azad honoured

Mr. Azad was also honoured on the occasion by Rotary International as ‘Polio Champion’ for his efforts to eradicate the disease from the country.

About 42 million children were expected to receive the new drops on Sunday. Overall, 170 million children are likely to be immunised during the current round of immunisation.

“We are committed to eradicating the polio menace from the country and focussed efforts will definitely bring desired results with the introduction of the bivalent vaccine in U.P., Delhi and Bihar,” Mr. Azad said, after administering polio drops to a few children at a function here.

Three strains

There are three strains of wild polio virus — P1, P2 and P3. Type 2 wild polio virus (P2) was eliminated in 1999. Efforts are still on to eradicate the P1 and P3 strains.

As P1 is the more virulent type of the two, the current strategy is to eliminate it first while keeping P3 under control.

Initially, a trivalent Oral Polio Vaccine (which caters to all three strains of the wild polio virus) was used in the campaign. Subsequently, a more efficient monovalent vaccine was introduced to handle the P1 and P3 strains.

While the monovalent vaccine has been found to be effective in containing the transmission of P1, it has affected the control of transmission of P3.

As many as 33 States and Union Territories are now free of indigenous transmission of the wild polio virus. Only U.P. and Bihar remain the two endemic States where indigenous transmission continues.

721 cases in 2009

For 2009, 721 cases were reported. Of these, 641 are of the wild poliovirus type 3 (WPV3) and 79 of the wild poliovirus type 1 (WPV1), with one case a mixture of both WPV1 and WPV3.