OPV in full is Oral Polio Vaccine (OPV). It is the best way to prevent polio. There are 4 doses. OPV is suitable for babies as young as 6-12 weeks, children and adults. Immunisation as a baby is best. Polio is an incurable disease which is spread easily from person-to-person and through contaminated food/drinking water.
Attribution: Straight Talk Foundation & Marie Stopes