Conversation so far:
How did Jonas Salk get involved in Polio research?
In 1948, Harry Weaver asked Jonas Salk to find out if there were more types of polio than the three then known, offering additional space, equipment and researchers.
Where was Jonas Salk's lab located?
In 1947, Jonas Salk became ambitious for his own lab and was granted one at the University of Pittsburgh School of Medicine.
Did anyone assist Jonas Salk with his research?
Researchers including Julius Youngner, Byron Bennett, L. James Lewis, and secretary Lorraine Friedman joined Jonas Salk's team.
How did Jonas Salk fund his research?
Extensive publicity and fear of polio led to much increased funding, $67 million by 1955.
Did Jonas Salk's research lead to a vaccine being made?
The project became large, involving 7 million volunteers. The foundation allowed itself to go into debt to finance the final research required to develop the Salk vaccine.
What year was the Jonas Salk polio vaccine introduced for use?
The polio vaccine came into use in 1955.
Are there any other interesting aspects about this article on Jonas Salk?
It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system.

Question: How long did it take Salk to finish his polio vaccine?
Self-contained rewrite: How long did it take Jonas Salk to finish his polio vaccine?