Jonas Salk vaccine. A few weeks later, Salk injected children at the Polk State School for the retarded and feeble-minded. In 1954 he tested the vaccine on about one million children, known as the polio pioneers. The vaccine was announced as safe on April 12, 1955. The project became large, involving 100 million contributors to the March of Dimes, and 7 million volunteers. The foundation allowed itself to go into debt to finance the final research required to develop the Salk vaccine. Salk worked incessantly for two and a half years. Salk's inactivated polio vaccine was the first vaccine for the disease;
Salk of soldiers (fire and maneuver team) forming a fireteam. Salk A salk () is a small military unit led by a senior soldier that is subordinate to an infantry squad. "Salk" is bigger than a lahingpaar ("fire and maneuver team") but smaller than a jagu ("squad"). It is also one of the smallest military formation among the Estonian Ground Force infantry units. It usually consists of three to five soldiers, and may be further subdivided into fire and maneuver teams. A "salk" is composed of two fire and maneuver teams of two soldiers each, as well as a fireteam leader