Normal, IL, USA / www.cities929.com Dec 14, 2020 4:27 PM (The Center Square) â The University of Illinoisâ rapid COVID-19 saliva test, also known as SHIELD, is on the wish list of other universities around the state. According to SHIELDâs website, the saliva test has a specificity between 99.8-99.9% with very false positives. Specificity refers to the proportion of people who are positive for a disease that is diagnosed to be positive. The president of the U of I, Dr. Thomas Killeen, testified at a Senate Higher Education Hearing on Monday that the test has been highly effective. âIt works because it lets us see where the virus is,â Killeen said. âIt looks at the whole iceberg, not just the tip.â