Saliva testing for Covid-19 may just be better than nasal swabs and cheaper too. It's preliminary, but Yale University has published a letter in The New England Journal of Medicine that showed saliva testing from the mouth picked up more positive Covid-19 patients than nasopharyngeal swab testing.
The patients they studied were already hospitalized and had tested positive for Covid-19. They re-tested them with nasal and saliva tests and found at 1 to 5 days after diagnosis 81% of saliva samples were positive compared to 71% of the nasal swabs. And at 6-10 days after diagnosis, 76% of the saliva samples were positive, compared with 65% of the nasopharyngeal swab specimens. This is important because of the shortage of medical supplies, inability to self test nasal swabs, and the ability of using common and available reagents in the saliva test. If one reagent is out of stock (or price gouging is going on), another can be used. Yale is sharing their protocol so others can replicate it, similar to "open-source" in tech.
The Yale SalivaDirect test should help with test cost, availability, ability to test in schools and businesses and the ability to self-test. Now all we need is a point-of-care (POC) test that gives us an instant answer like a home pregnancy test. This is being studied at the University of Illinois and I look forward to their results.
Imagine that! Developing something to benefit others with scientific integrity! Way to go, Yale!