Poliomyelitis leading to large-scale trials in the then Belgian Congo and the vaccination of seven million children in Poland against serotypes PV1 and PV3 between 1958 and 1960. The second inactivated polio virus vaccine was developed in 1952 by Jonas Salk at the University of Pittsburgh, and announced to the world on 12 April 1955. The Salk vaccine, or inactivated poliovirus vaccine, is based on poliovirus grown in a type of monkey kidney tissue culture (vero cell line), which is chemically inactivated with formalin. After two doses of inactivated poliovirus vaccine (given by injection), 90 percent or more of individuals develop
Salk "salk" is meant to operate on a battlefield along with other "salk's" on a landscale not greater than 50 x 100 metres. There are no logistical support elements in the structure of a "jagu". In the Canadian Army 'fireteam' refers to two soldiers paired for fire and movement. Two fireteams form an 'assault group' and two assault groups form a section of eight soldiers. Many other armed forces see the squad as the smallest military unit; some countries' armies have a pair consisting of two soldiers as the smallest military unit. In others a fireteam is composed of two pairs