Dr Jonas Salk was an American medical researcher and virologist, best known for his discovery and development of the first safe and effective polio vaccine. You can read more about Dr Salk at this Wikipedia page. Watch this short video (41 seconds) to see the actual announcement on 12 April 1955 that the Salk vaccine had been found to be “safe, effective and potent”. The Salk injected poliovirus vaccine (IPV) was introduced in Australia in 1956.
An episode of the BBC World Service Witness program which was first broadcast on 11 April 2014 revisited the discovery of the polio vaccine by Dr Salk: “American scientists announced they had discovered an effective vaccine against polio in April 1955. It would save millions of children from disability and death. The doctor who led the research was Jonas Salk. Hear from his son Peter and a nurse who worked with him.”
Duration: 9 mins 4 secs
The American Academy of Achievement conducted this extensive interview (1 hour 27 mins) with Dr Salk in 1991 and has generously made the video and transcript freely available. (The transcript contains the complete interview and includes a number of photos.)