New COVID-19 Test Results in 45 Minutes, Without a Painful Nasal Swab

CU Boulder researchers have developed a fast, portable, saliva-based COVID-19 test that can return results in 45 minutes. Such a test could eventually be deployed in community settings such as schools and factories.

“We are facing a severe test shortage in this country now that more people want to be tested and the diagnostic labs are overwhelmed,” said Nicholas Meyerson, a postdoctoral associate at the Sawyer Laboratory at the BioFrontiers Institute in CU Boulder. “We have developed a test that could give people results much faster.”

The test, described in a preprinted manuscript published Friday in the online archive MedRxiv.org, is designed for widespread examination to help identify asymptomatic individuals. Research shows that people infected with the virus but without obvious symptoms account for up to 70% of cases and can still transmit the disease. In this new test, a user spits into a tube, adds a solution to stabilize it, then closes the lid and hands it over to test personnel. They process it through a simple system that requires little more than pipettes, a heating source, and a mixture of enzymes.

If the sample changes from pink to yellow, the test is positive. If not, it is negative.

Because swabs are not required, and sophisticated equipment is not needed, the tests are less vulnerable to delays and supply chain shortages, the researchers say.

“Every test approved to date requires that the sample, even if it is saliva, be processed in a clinical diagnostic laboratory or doctor’s office, using sophisticated equipment. That can take up to nine days at this time,” said the Professor Sara Sawyer, virologist from the Department of Cellular and Developmental Molecular Biology who led the development of the test.

Frequent and quick test key to stop the spread

The test builds on a 20-year-old technology known as reverse transcription loop-mediated isothermal amplification (RT-LAMP) previously used, for example, to detect mosquitoes for the Zika virus in remote regions of South America.

Once a sample is collected, it is heated to release any viral genomes present in the test fluid. This sample is then added to three tubes, each of which contains a custom enzyme mixture that, when heated to a certain temperature, undergoes a chemical reaction when the genetic material of SARS-CoV-2 is detected. That is the virus that causes COVID-19.

In an experiment described in the article, the researchers carried out what is known as “artificial clinical validation.” An investigator added 30 out of 60 saliva samples with inactivated SARS-CoV-2 in the laboratory. They then shuffled the samples and gave them to another scientist to test with RT-LAMP technology.

“The test predicted 100% accuracy with all negative samples, and 29 out of 30 positive samples were accurately predicted,” Meyerson said, noting that test number 30 was rated inconclusive. Additional third-party validation tests are currently underway.

The authors note that the test is slightly less sensitive than those performed in clinical laboratories. But another computer modeling study, also conducted by researchers at the BioFrontiers Institute, found that rapid change for testing is even more critical to curbing the pandemic than test sensitivity.

“Our model demonstrated that whether a test is sensitive or super sensitive is not that important,” said BioFrontiers director Roy Parker, co-author of that paper, which has not yet been peer-reviewed. “The important thing is frequent testing, with test results as quickly as possible, which identifies more infected people faster and can limit new infections.”

Ideally, the team sees the test as a “triaging tool”.

“Those who test positive can be quarantined while waiting for confirmation tests,” Sawyer said.

The research team, in cooperation with Venture Partners at CU Boulder, has created a spin-off, Darwin Biosciences, to market the test. The company is also working on a DIY rapid test for infectious diseases, known as SickStick, which is based on a different technology and is packaged as a home pregnancy test. Expect it to be available through outlets one day.

“While we are all very optimistic about a coronavirus vaccine, scientists have been working on an HIV vaccine for 30 years without success,” said Sawyer. “Meanwhile, the HIV pandemic showed us that widespread testing can make a big difference.”