Today, Covid-19 vaccinations require one or two injections. In the late 1950s, vaccinations against polio required three injections of Salk Vaccine. The recommended schedule called for a second injection 4 weeks after the first, and a third 7 months following the second.  A California law required school children to be vaccinated.  All three shots had to be completed within a one-year span. In late 1962 Sabin Vaccine became available in the form of a sugar cube taken orally.  Three immunizations were required over a period of six months. In March 1963, the Mill Valley Record reported, “Southern Marin turned out in surprisingly few numbers last Sunday with 23,802 persons receiving their third and final K. O. Polio Sabin Vaccine at four clinics in Mill Valley, Tiburon and Sausalito. With an estimated total population of 41,679 Southern Marin turn out was 57%. Marin County, however, led the Bay Area turn out with 65%, aided by a fantastic 80% showing by citizens of West Marin. The turn out was deemed to be very satisfactory by Marin medicos. The final Sunday clinic was the end of a gigantic effort to wipe out three strains of the polio virus in the Bay Area.”