The OPV (Oral Polio Vaccine) is specifically designed to prevent Poliomyelitis, a highly infectious viral disease that primarily affects children and can cause permanent paralysis. OPV contains a weakened form of the poliovirus, which stimulates the immune system to produce antibodies without causing the disease. It is administered orally, making it easy to deliver during mass vaccination campaigns. OPV is preferred in many regions due to its ability to provide both individual immunity and community-wide protection through herd immunity. This vaccine is not used for diseases like measles, hepatitis B, or tetanus, which require different vaccines.

Reference: Harrison's Principles of Internal Medicine, Longo et al., 20th Edition.