The race is on for a covid-19 test you can take at home

You are feeling feverish and have a cough. Is it just a cold, or is it covid-19? That's a question that's going to be hanging over all of us, possibly for several years.

Right now, getting tested for the coronavirus means going to a doctor or a drive-in clinic and potentially exposing other people, and even then, a test can be hard to obtain. The US Centers for Disease Control is still telling people that if their symptoms are mild, they should simply stay at home.

That's why some companies are now trying to develop at-home genetic tests to spot the virus. They include Mammoth Biosciences, a startup in South San Francisco, California, that makes tests using the CRISPR gene-editing technology; the company said today it plans to have a disposable home test kit ready by year's end.

The kit will be designed and manufactured by GSK Consumer Healthcare. GSK already sells toothpaste, nicotine gum, and over-the-counter medicines to consumers.

CRISPR is best known as the gene-editing tool used to modify animals or correct genetic disease. But it can also be employed in diagnostic tests because it is able to zero in on very specific genetic information-like the genetic sequence of a virus-and then trigger a visible signal, similar to the bars that appear on a home pregnancy test.

The pandemic has added propellant behind the idea of using CRISRP for testing. That's because the technology has features that make a portable test feasible: it is quick, requires little machinery, and works on raw samples like spit or snot.

It's the ultimate use case for CRISPR," says Trevor Martin, the CEO of Mammoth. Our vision is that it would be in the format of a pregnancy test."

Right now, the most accurate covid-19 tests are molecular tests run in central labs, typically employing a technique called PCR, which requires several processing steps. The aim of companies like Mammoth is to skip PCR, making the costly equipment and trained technicians unnecessary.

You want to make the type of testing you are doing at home the same level of accuracy as in a lab," Martin says. You don't want a trade-off, and that has not been possible so far."

A prototype of Mammoth's new covid-19 test.MAMMOTH BIOSCIENCES

In April, University of California researchers working with Mammoth demonstrated that CRISPR could spot the coronavirus. So did two other diagnostics companies working with the technology, Sherlock Biosciences and Caspr Biotech. Getting a product to market is not about demonstrating the technology works. That took us a day," Rahul Dhanda, CEO of Sherlock, said during an interview in March.

His company later won emergency approval to sell a lab-only version of its CRISPR test, although it's still not in use.

Home test

It's unclear how much home tests would really do to control the pandemic or limit new infections. An analysis by Imperial College found that regular covid-19 screening should be used with high-risk groups-say, to test health-care workers every week. That analysis saw less benefit for testing the population as a whole over just asking people with symptoms to self-quarantine.

If people test at home, they might not report the results to health authorities, limiting visibility into the spread of the pandemic. Without a doctor involved, they also might not get or follow medical advice about quarantining or alerting contacts.

Providing home-based tests to individuals without a component of required reporting means missing potentially critical public health information," says Donald Thea, a professor of global health at Boston University.

GSK, which does not currently sell over-the-counter tests, did not answer questions about what benefits it sees for home testing. Martin said Mammoth has not determined the details of how its tests would work, but they could include an app that would record and report anonymized results. In general, more information is better, especially in a pandemic, and I would trust people to act on it," he says.

Drugstores already sell home tests for HIV, cholesterol levels, and allergies, but none of those are genetic tests. Current consumer gene tests, for paternity or ancestry, ask people to mail in a sample of spit or hair.

In April, the US Food and Drug Administration allowed LabCorpto introduce a mail-in sample collection kit for covid-19, but it still takes several days to get results.

In addition to consumer use, a quick and easy covid-19 test might be in demand by governments and companies like airlines, which want to vouch that people aren't introducing the infection at ports of entry. Martin calls screening arrivals to a country a clear use case" and says he's been in touch with various government agencies" about the possibility.

Future of testing

Mammoth was founded by scientists including CRISPR co-discoverer Jennifer Doudna of the University of California, Berkeley, who saw the versatile technology as a potential tool to revolutionize diagnostics. If the covid-19 pandemic leads to the first at-home gene tests, it's likely CRISPR could be adapted to the next emerging disease or new consumer uses, like testing for venereal diseases or strep throat.

If the technology can be reduced and simplified so it's easy to use and home-based, theoretically you could use it to find any pathogen with DNA or RNA," says Thea. There's going to be a real revolution in viral diagnostics, [and] coronavirus is really accelerating that. That's one of the unintended but hopeful consequences of a truly horrible situation."