Yale-developed, NBA-funded saliva test costing $10 per test could make frequent testing of asymptomatic people feasible.
There’s a lot of positive buzz today about an inexpensive saliva test for SARS-Cov-2 developed by researchers at the Yale School of Public with funding from National Basketball Association and the league’s players association.
The test, which the Yale researchers have dubbed SalivaDirect, was given an emergency use authorization (not a full-fledged approval but a green light, nonetheless) by the FDA yesterday.
“This could be one [of] the first major game changers in fighting the epidemic,” tweeted Andy Slavitt, a former CMS administrator in the Obama administration who has had a major presence on Twitter during the COVID-19.
The test uses a readily available enzyme, proteinase K, and heat to make SARS-CoV-2 RNA detectable in a saliva sample instead of using kits to extract the RNA in multistep process that is time-consuming and adds expense.
"We use proteinase K and heat to essentially break open the SARS-CoV-2 virus particles to release the genetic material, so that if present we can detect it with the PCR test," Chantal B.F. Vogels, one of the Yale researchers, said in an email to Managed Healthcare Executive® today.
Four steps of SalivaDirect test for SARS-CoV-2. Illustration created with biorender.com
“Being able to perform a test without these kits enhances the capacity for increased testing, while reducing the strain on available resources,” the FDA said its announcement yesterday about the emergency use authorization.
The Yale researcher say on their COVID-19 website, Covidtrackerct.com, that their SalivaDirect is a protocol — not a kit — that “we can allow authorized labs to use with reagents that can be purchased for very cheap.” Moreover, they say the protocol is free for use by CLIA-certified labs. The Yale group, headed by Nathan Grubaugh, say they will issue licenses free to for-profit companies but will want to negotiate how much the for-profit companies charge.
In a paper posted August 4 on Medrxiv, the preprint publishing platform of research before it has been peer reviewed that has become popular during the pandemic, the Yale researchers put the cost of their test at between $1.29 and $4.37. Once lab fees and overhead are added, it might rise to roughly $10 a test.
“At a $10 test, you can test every day or every couple of days. This is even more important than accuracy,” tweeted Slavitt, noting also that widespread, inexpensive testing of asymptomatic people will be important to universities and people working in office buildings.
In the Medrxiv paper, Yale researchers compared their SalivaDirect test and with a ThermoFisher test of nasopharyngeal samples. Their test detected virus in 32 of the 34 cases (94%) that the ThermoFisher test detected virus.
"SalivaDirect has a high sensitivity," Vogels said in her email. "However, if a sample is very weakly positive (for instance a patient who is recovering) then we might miss some of these."
The Yale researchers also said their data show that SARS-CoV-2 RNA is stable without preservatives added to the saliva for at least seven days when stored at temperatures up to 86˚F. They also reported that their results didn’t materially change when they used proteinase K from three different vendors. However, their tests of different PCR kits did show differences, with some detecting the virus at lower levels than others, and they cautioned in the Medrxiv paper that not all PCR kits may be suitable for use with their saliva-based protocol.
ESPN reported yesterday that the NBA and the players' association contributed $500,000 to the Yale work.
The Yale researchers say they are currently enrolling NBA players and staff in a study designed to compare their saliva test with a conventional test that depends nasopharyngeal samples. Results from SWISH (Surveillance With Improved Screening and Health) should be available later this month, according to the website.