Spit Works

A new paper finds that COVID-19 can be detected in saliva more accurately than with nasal swab. As I mentioned earlier a saliva test will lessen the need for personnel with PPE to collect samples.

Rapid and accurate SARS-CoV-2 diagnostic testing is essential for controlling the ongoing COVID-19 pandemic. The current gold standard for COVID-19 diagnosis is real-time RT-PCR detection of SARS-CoV-2 from nasopharyngeal swabs. Low sensitivity, exposure risks to healthcare workers, and global shortages of swabs and personal protective equipment, however, necessitate the validation of new diagnostic approaches. Saliva is a promising candidate for SARS-CoV-2 diagnostics because (1) collection is minimally invasive and can reliably be self-administered and (2) saliva has exhibited comparable sensitivity to nasopharyngeal swabs in detection of other respiratory pathogens, including endemic human coronaviruses, in previous studies. To validate the use of saliva for SARS-CoV-2 detection, we tested nasopharyngeal and saliva samples from confirmed COVID-19 patients and self-collected samples from healthcare workers on COVID-19 wards. When we compared SARS-CoV-2 detection from patient-matched nasopharyngeal and saliva samples, we found that saliva yielded greater detection sensitivity and consistency throughout the course of infection. Furthermore, we report less variability in self-sample collection of saliva. Taken together, our findings demonstrate that saliva is a viable and more sensitive alternative to nasopharyngeal swabs and could enable at-home self-administered sample collection for accurate large-scale SARS-CoV-2 testing.

The FDA has also just approved an at-home test collected by nasal swab, a saliva test should not be far behind.

Hat tip: Cat in the Hat.


Super good news if it really works.

You're right, we need the Hammer and the Flat, but it has to be carefully traded off against R > X, where X is the factor of immigrants in any given contact.

Swallow works. I prefer swallowing.

LOL, prior posting as me in the middle of the night, US Central time. That's some desperation.

USPS.com -- 346.12 Division 6.2, Infectious Substances
Division 6.2 materials include infectious substances, biological products, regulated medical waste, sharps medical waste, used health care products, and forensic materials. Division 6.2 materials are not permitted in international mail or domestic mail, except when they are intended for medical or veterinary use, research, or laboratory certification related to the public health; and only when such materials are properly prepared for mailing to withstand shocks, pressure changes, and other conditions related to ordinary handling in transit.

Solves part of the sampling problem, assuming it actually works.

Can company in the other link run 20 million samples a day? 10 million? 5 million? 1 million? It is one thing to get a million samples a day from people- another to actually process them in a time frame that actually matters. And I still object to calling this a "home test". It is a home sampling, not a home test.

How much of the testing problem could we solve if we just ran tests by household instead of by individual? If anyone in the house tests positive, everyone is going to have to be quarantined anyway. It might make contact tracing require more work, but that seems like an easier and quicker problem to solve than getting more tests.

The FDA must get the experts in quality assurance of testing, the CDC, to watch all these new, untested, tests and make sure they are good.

@Dismalist - what's your definition of good? How accurate is accurate enough? And what's the appropriate trade-off between false positive rates and false negative?

How long do we go without tests while we make these decisions? Part of the reason we're in this mess is that we haven't been able to pivot from our normal mode of allowing the perfect to be the enemy of the good where we never act until we can be sure nothing will ever go wrong. The problem with that is that when you're dealing with a threat that grows exponentially, it's game over before you've made a move.

Thank you for sharing the great useful news. Hope we can defeat the virus in soon.

This clears one important bottleneck. The results show greater counts in saliva but we should just get going. Sadly the next bottleneck (reagents, analysis platforms) are unlikely to be so easily hurdeled. But an important step forward.

How viable is group testing. Take ten samples put them together. If they test negative all 10 are cleared for the price of one. If positive split into groups of 5 and repeat.

It works and is being put into practice in some places, most recently in parts of India: https://www.livemint.com/news/india/pooling-can-help-india-optimize-its-testing-strategy-11587578644506.html

What kind of sadist would start testing by shoving giant sticks up your nose before ruling out saliva-based tests?

I’m sure I’m oversimplifying this, but should it really have taken 3-4 months to start testing the more intuitive and less invasive way?

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