stimulate both humoral and cell mediated immunity,stimulate IgA Antibodies at the portal site of entery of the virus , long duration of immunity,with out booster dose with fewer antigen,stimulate production of systemic IgM and IgG
According to the polio eradication plan led by WHO, poliovirus type 2 component of the oral poliovirus vaccine should be withdrawn worldwide. The alteration is from trivalent oral poliovirus vaccine (tOPV) to bivalent oral poliovirus vaccine (bOPV). The swap is anticipated to avert the paralytic polio cases due to circulating vaccine-derived poliovirus type 2.