Regularly testing large numbers of people will play a huge role in monitoring transmission of SARS-CoV-2. Quickly detecting and isolating active cases – people who can transmit the virus, whether symptomatic or asymptomatic – is the cornerstone for limiting disease spread. In addition, accurate data on the number of active cases is necessary to inform policy makers (at local, state, and federal levels) as well as individuals what the short-term risk of spread is and how safe it is to do things like return to workplaces, attend school, and see friends and family.
There are a few problems the world has had to face when trying to build surveillance for SARS-CoV-2. Nasopharyngeal swabs, or “NP swabs,” have to be collected by someone who is trained to do so, adding a logistical barrier and putting those performing the test at risk of getting sick. They also can be uncomfortable, which discourages people from getting tested frequently. Because SARS-CoV-2 rapidly spread worldwide, it has put immense strain on the supply chains that provide materials for tests, including swabs and test reagents. SalivaDirect is our answer to these problems.
SalivaDirect is a new method for testing people for active SARS-CoV-2 infection, with or without symptoms. While it still relies on a similar molecular process as earlier tests (called RT-qPCR), we are making it simpler to drive down costs and place less stress on the supply chains.
SalivaDirect is unique in 3 ways:
- We test from Saliva, not NP swabs. This means that you can collect it yourself without an uncomfortable swab up your nose. This also protects healthcare workers from potential exposure to sick patients and works around worldwide swab shortages.
- It doesn’t require extracting the nucleic acid from samples before testing. Nucleic acid extraction is time-consuming and expensive, and there have been worldwide shortages of the supplies needed to do it. For SalivaDirect, we’ve worked out how to skip this step, making it accessible to more labs.
- Our test is flexible. While many labs have similar supplies, they may be from a different company or a slightly different type. We are aiming to test our method with as many different variations of equipment and reagents as possible to allow labs to work with what they have and to prevent shortages.
We plan to submit SalivaDirect for FDA Emergency Use Authorization by early July.
What’s next?
Once SalivaDirect has Emergency Use Authorization from the FDA, it will be a great tool that labs can use for rapidly testing people while eliminating supply chain issues. But we’re not satisfied yet; we are still doing research on how to increase the number of people that can be tested per day and reduce the supplies and equipment needed per test. We hope that this will make SalivaDirect an even better option for low-resource and remote settings. There are two more experiments we’re performing to make it even better, the results of which will also be posted here as we go along:
- Pooling. By combining saliva from many people and testing it all at once, we can increase the number of samples that can be tested per day and reduce the amount of each reagent used per person.
- Stability. All other ways of collecting samples require that the sample is held in a refrigerator or freezer between collection and testing, or placed into expensive tubes containing reagents advertised to help maintain the quality of the sample for later testing. In remote or low-resource settings, which may not always have electricity or access to refrigeration, this is a major barrier, especially if fancy collection devices come with a higher price tag. We’re testing how well we can detect SARS-CoV-2 from saliva held at room temperature for days or even weeks.
SWISH
To determine if SalivaDirect can accurately detect asymptomatic cases, our team at the Yale School of Public Health are partnering with the NBA, as they look to continue playing while ensuring the health of players and staff. The partnership, the Surveillance with Improved Screening and Health (SWISH) Study involves side-by-side testing of samples collected from players and staff using a standard nasal/oral test for SARS-CoV-2 and SalivaDirect. We’ll compare the outcomes of each test, and post the results at the study conclusion (likely late July).