The first mass inoculation of children against polio with the Salk vaccine begins in Pittsburgh.

Poliomyelitis, commonly shortened to polio, is an infectious disease caused by the poliovirus. Approximately 75% of cases are asymptomatic; mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe symptoms develop such as headache, neck stiffness, and paresthesia. These symptoms usually pass within one or two weeks. A less common symptom is permanent paralysis, and possible death in extreme cases. Years after recovery, post-polio syndrome may occur, with a slow development of muscle weakness similar to what the person had during the initial infection.

Jonas Edward Salk was an American virologist and medical researcher who developed one of the first successful polio vaccines. He was born in New York City and attended the City College of New York and New York University School of Medicine.

A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the immune system to recognize the agent as a threat, destroy it, and recognize further and destroy any of the microorganisms associated with that agent that it may encounter in the future.

Pittsburgh is a city in Allegheny County, Pennsylvania, United States, and its county seat. The city is located in southwestern Pennsylvania at the confluence of the Allegheny River and Monongahela River, which combine to form the Ohio River. It is the second-most populous city in Pennsylvania with a population of 302,971 at the 2020 census, while the Pittsburgh metropolitan area at over 2.43 million residents is the largest metropolitan area in both the Ohio Valley and Appalachia, the second-largest in Pennsylvania, and 28th-largest in the U.S. The greater Pittsburgh–Weirton–Steubenville combined statistical area includes parts of Ohio and West Virginia.