Polio vaccine in several other African nations without necessary information, which epidemiologists believe is due to refusals by certain local populations to allow their children to receive the polio vaccine. The Salk vaccine, IPV, is based on three wild, virulent reference strains, Mahoney (type 1 poliovirus), MEF-1 (type 2 poliovirus), and Saukett (type 3 poliovirus), grown in a type of monkey kidney tissue culture (Vero cell line), which are then inactivated with formalin. The injected Salk vaccine confers IgG-mediated immunity in the bloodstream, which prevents polio infection from progressing to viremia and protects the motor neurons, thus eliminating the risk of bulbar
Jonas Salk Times", a few months after his vaccine announcement. The "Times" article noted, "at 40, the once obscure scientist ... was lifted from his laboratory almost to the level of a folk hero." He received a presidential citation, a score of awards, four honorary degrees, half a dozen foreign decorations, and letters from thousands of fellow citizens. His alma mater, City College of New York, gave him an honorary degree as Doctor of Laws. But "despite such very nice tributes", "The New York Times" wrote, "Salk is profoundly disturbed by the torrent of fame that has descended upon him. ... He