What do you mean by Polio drops ?

Concept and Significance of Polio Drops (Oral Polio Vaccine - OPV):

Polio Drops refer to the Oral Polio Vaccine (OPV), an oral immunizing suspension developed by virologist Albert Sabin in 1961 containing live-attenuated strains of Poliovirus (Types 1, 2, and 3):

• Mechanism of Action: Administered orally (2 drops: "Do Boond Zindagi Ki"), OPV replicates in the child's intestinal tract, inducing mucosal local intestinal immunity ($IgA$) and systemic antibodies ($IgG$), preventing wild poliovirus from multiplying and invading the central nervous system (paralytic poliomyelitis).
• Secondary Benefit (Contact Immunity): The attenuated vaccine virus is shed in feces, passively immunizing other children in unhygienic community settings.
• Pulse Polio Immunization Drive (PPIP, 1995): Mass administration on National Immunization Days (NIDs) across India successfully eliminated wild polio transmission, leading to WHO certifying India Polio-Free in March 2014.
• Bivalent OPV (bOPV) & fIPV Transition: Modern protocols deploy bOPV (Types 1 & 3) alongside Fractional Inactivated Polio Vaccine (fIPV) injections to prevent vaccine-derived polio.