MODEL RELEASED. Polio vaccine research. Researcher analysing a multi-well sample tray containing samples of poliovirus in an infectivity assay. This was done to test the efficiency of a vaccine. Polio viruses cause poliomyelitis, usually just called polio, a disease that causes a range of symptoms from fever and headache to paralysis and even death. A vaccine has been available since the 1950s, and in the developed world the disease is very rare. In developing countries, however, polio can occur in devastating epidemics. Vaccines against the three types of polio viruses are usually given before nine months of age.