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
His Name Is Legs (Ladies and Gentlemen) before undertaking a much-anticipated North American tour with Ravi Shankar. With Peter Sellers among his entourage, Harrison alternatively adopted comedy and his Hindu-aligned spiritual goals as a defence against expectations related to his Beatle past during the tour.<ref name="Fong-Torres/2001">Ben Fong-Torres, "George Harrison: Harrison in the Haight", "San Francisco Chronicle", 2 December 2001; available at Rock's Backpages (subscription required).</ref> When discussing "His Name Is Legs" with BBC Radio 1 DJ Paul Gambaccini in September 1975, Harrison said that after recording the basic track, he invited Smith to sing the first two lines of each of the bridges. Smith did these vocal