- FDA over the weekend granted emergency use authorization to a COVID-19 saliva test from the Yale School of Public Health that lacks a separate nucleic acid extraction step and eliminates the need for a special swab or collection device. Samples collected in any sterile container are suitable.
- Yale is set to start offering the test from its CLIA-certified clinical laboratory, where it could double capacity, and make the protocol available to other facilities.
- While the FDA commissioner touted the approval as potentially groundbreaking, at least one prominent public health expert cautioned that hurdles remain, including the need for robots and other special equipment for processing the results.
The rapid global increase in COVID-19 testing created multiple bottlenecks. One problem relates to the RNA extraction step. At best, that step adds to the turnaround time. At worst, a lack of access to RNA extraction kits constrains capacity. An Association for Molecular Pathology survey found 81% of laboratories have faced shortages of RNA extraction kits and other reagents during the pandemic.
Only two COVID-19 testing components have faced more widespread supply issues, namely swabs and transport media. Around 90% of laboratories have struggled to access those components.
Yale's protocol, dubbed SalivaDirect, could enable laboratories to test people for COVID-19 even if they lack RNA extraction kits, swabs and transport media. Saliva is collected in any sterile container, without preservatives and in the absence of healthcare professional oversight, and analyzed using real-time reverse transcription polymerase chain reaction instruments.
Other organizations already have EUAs for saliva-based COVID-19 tests. A Rutgers University lab got an EUA for a saliva test in April. Since then, FDA has authorized more saliva-based tests, including ones that support at-home sample collection without the supervision of a healthcare professional.
SalivaDirect is differentiated from other tests through its elimination of the RNA extraction step and the need for special collection devices, as well as by the way the university is making its protocol widely available. Yale is making the protocol available to labs that want to run the test.
As the protocol can use a number of commercially available reagents and instruments, such as those sold by Bio-Rad and ThermoFisher Scientific, any laboratory designated by Yale can adopt it and start offering COVID-19 testing. In theory, the protocol could therefore drive down the cost of testing and increase capacity.
Michael Mina, an epidemiologist at the Harvard School of Public Health, cautioned against overplaying the significance and underplaying challenges. He called the development an incremental step forward, but added:
"It is important to note that despite use of saliva and simplifying the RNA extraction - SalivaDirect remains a laboratory based test that must be performed in highly specialized high-complexity CLIA clinical laboratories. It is not a rapid test," he wrote on Twitter.
Yale received financial support from the NBA and the National Basketball Players Association, which were also involved in the assessment of the test.
Yale received the EUA on the strength of evidence showing SalivaDirect yielded the same result as the ThermoFisher Scientific TaqPath COVID-19 combo kit more than 90% of the time when used to analyze positive and negative samples. FDA said it has seen "variable performance in tests using saliva" but the Yale test met its EUA criteria.