Developing a saliva test to detect COVID-19

My name is Anne Wylie, I'm a research scientist at the Yale School of Public Health and principal investigator of SalivaDirect. So, it was already back in May 2020 that we decided to focus on saliva as a sample type when we recognized there was going to be a need for frequent repeat testing going forward. And at that time, the only alternative was the gold standard nasopharyngeal swab. And the benefit of saliva is that it's so easy to self-collect. It's non-invasive. And so, it's much more amenable to the general population to think about giving a saliva sample as compared to that deeper nasopharyngeal swab. Oh, saliva is definitely not a traditional diagnostic sample type. It can be very variable in the types of samples that I collected. Samples can be different viscosity, which means that they can be different or even difficult to work with. But what we found is that we've just developed a really straightforward collection protocol that really lays out to the individual that we are just wanting their normal saliva that just naturally pulls in their mouth, so they're not supposed to, like, cough or sneeze anything. And by giving these very clear instructions, our laboratory network across the entire...you know, we're in 166 labs and 41 states across the country. And they're reporting that the majority of the samples coming through, the vast majority, are all perfectly fine to work with and giving them accurate results. SalivaDirect has been able to detect all SARS‑CoV‑2 variants to date. We are very aware, however, that we do only target one SARS‑CoV‑2 target that's the N1 gene. When developing SalivaDirect, however, having only one target did make the test more sensitive because you don't have different reagents competing for the different targets. It's something that we're acutely aware of. However, we have developed alternate assays in the background. We are exploring additional gene targets. We do keep an eye on the different variants that are arising and any possible mutations to that N1 region that could affect the sensitivity of our test. So, what's unique about the SalivaDirect test is that we went for the open-source protocol approach right from the very start. For every step of the protocol, we have validated multiple instruments, multiple reagents from multiple manufacturers such as LGC Biosearch Technologies, for example. And this is really to enable labs to utilize what they already had in place in their lab or to utilize their existing supply chain. Or on the other hand, should, you know, testing demands increase, should supply chain disruptions occur, there's also additional suppliers that labs can go to make sure that their testing is not affected by any of these unforeseen events. SalivaDirect has actually been described as being very similar to a high school biology protocol. So, it is very straightforward. It's very easy to set up. There's not many steps at all. So, we just ask labs to share with us their clear verification data showing that they have been able to successfully implement SalivaDirect in their lab. And generally, the majority of the time the data has come through looking, you know, spot on. Every now and then there's been just a couple of tweaks that we've had to make in terms of, you know, maybe the positive control not being diluted down far enough. But just, you know, it's been really great to see the consistency. And it's actually been really encouraging to hear the labs who were more traditionally focused on swabs, who have moved a lot of their testing over to saliva, and that they're actually finding more reliable or consistent results with saliva, as compared to the nasal swabs that they get in. I'm really hoping that this approach is going to be transformative for public health or in vitro diagnostics in the future as well. I mean, we're showing what can be done when you pull together a network of clinical labs across the country, and how easily we can then roll out any of these amendments that we make to our protocol. So, whether this is for future variant detection for SARS-CoV-2, or combining the assay to also target other respiratory viruses such as influenza or RSV. If we make these amendments to our protocol, those changes will be automatically available to all the labs in our network. Looking forward, we're currently working to expand SalivaDirect for the detection of additional respiratory viruses such as Flu, RSV. If you can have these all combined into one simple test to try and identify the cause of someone's flu-like symptoms, and how you respond to that, I think that's gonna have great implications for public health. I'm also just curious to see, like, what we've learned in terms of validating and optimizing saliva as a diagnostic sample type, but this could also mean, for different disease detection, or even public health surveillance as well.