Polio vaccine is usually provided in vials containing 10–20 doses of vaccine. A single dose of oral polio vaccine (usually two drops) contains 1,000,000 infectious units of Sabin 1 (effective against PV1), 100,000 infectious units of the Sabin 2 strain, and 600,000 infectious units of Sabin 3. The vaccine contains small traces of antibiotics—neomycin and streptomycin—but does not contain preservatives. In a generic sense, vaccination works by priming the immune system with an 'immunogen'. Stimulating immune response, by use of an infectious agent, is known as immunization. The development of immunity to polio efficiently blocks person-to-person transmission of wild poliovirus, thereby protecting
6 Songs for Bruce 6 Songs for Bruce 6 Songs for Bruce, also commonly known as 4-Track Demo, is an early single-sided demo cassette tape by American rock band Soundgarden. The band, at the time a three-piece named Sound Garden, composed of guitarist Kim Thayil, bassist Hiro Yamamoto, and Chris Cornell on drums and vocals, recorded the demo in Jack Endino's basement four-track studio on April 24, 1985 for their friend Bruce Pavitt, hence the name of the tape, which features a rare early version of "Tears to Forget" sung by Yamamoto, and, as a bonus song, a Cornell's solo recording titled "The Storm".