AGARTALA, April 19 (TIWN): With the initiative of national health mission, a state level media sensitization program was organised on Tuesday at press club on tOPV to bOPV Switch.

The workshop was conducted to prepare the health workers to switch from Trivalent Oral Polio Vaccine (tOPV) to Bivalent Oral Polio vaccine (bOPV). tOPV is being used now in Routine Immunizations and Polio Campaigns.

It contains all 3 types of Polioviruses- type 1, 2 & 3. Since the polio type 2 has been eradicated from the world, bivalent oral polio vaccine (bOPV) will totally replace tOPV throughout the world. This is called the Switch. It will be globally co-ordinated and in a two week window from April 2016. In India, the National Switch Day will be April 25, when bOPV will replace tOPV.

It is to be mentioned here that bivalent oral polio vaccine (bOPV) consists of live, attenuated (weakened) poliovirus strains of type 1 and type 3. It simultaneously targets the two remaining types of wild poliovirus (type 1 and type 3) and was developed to improve the efficiency and impact of vaccination campaigns in areas where both types of poliovirus co-circulate.

Bivalent oral polio vaccine was first used in Afghanistan in December 2009, when 2.8 million children under five years old received the vaccine.

The switch from tOPV to bOPV will be a globally coordinated process in April 2016. Timely planning and implementation of such a plan will allow countries to successfully recall and dispose of tOPV, minimize tOPV wastage, validate tOPV dispoal, and contribute to a world free of circulating vaccine-derived type 2 polioviruses.

Globally, polio cases have reached an all-time low, and type 2 poliovirus (one of three) is eradicated. Oral polio vaccine (OPV) has been the primary tool, however, in rare cases, OPV induces paralysis. In 2013, the World Health Assembly endorsed the phased withdrawal of OPV and introduction of inactivated poliovirus vaccine (IPV) into childhood routine immunization schedules. Type 2 OPV will be withdrawn through a globally synchronized "switch" from trivalent OPV (all three types) to bivalent OPV (types 1 and 3). The switch will happen in 155 OPV-using countries between April 17th and May 1st, 2016. Planned activities to reduce type 2 outbreak risks post-switch include the following: tOPV campaigns to increase type 2 immunity prior to the switch, monovalent OPV2 stockpiling to respond to outbreaks should they occur, containment of both wild and vaccine type 2 viruses, enhanced acute flaccid paralysis (AFP) and environmental surveillance, outbreak response protocols, and ensured access to IPV and bivalent OPV.