Wednesday, October 21

Why the US so far behind on rapid testing for Covid-19

Despite having the highest infection rate in the world, the US currently conducts about 800,000 Covid-19 tests per day. As of August 2, that’s about 12.5 tests per confirmed case, far lower than many other countries hit hard by the virus, including Italy (96.4 tests per case) and Australia (113.3 tests per case).

As other countries have increased the number of people who get tested for Covid-19, many have also compressed the timeline for results. As of late July, travelers arriving at Tokyo’s Narita and Haneda airports are given rapid antigen tests with results in 30 minutes. The European Union had three rapid tests (pdf) that met its regulatory guidelines as early as March.

But in the US, where testing got off to a slow and rocky start, people still wait up to two weeks for their results, too late for them to be useful.

As a result, returning to reopened restaurants, offices, airports, and schools means taking a risk. As the infected continue to walk among us, undiagnosed and symptomless, screening methods intended to keep them out of shared spaces, such as temperature checks and questionnaires, aren’t very effective.

“Existing technologies are great, but it’s still just not going to be enough,” says Bruce Tromberg, the director of the National Institute of Biomedical Imaging and Bioengineering, a branch of the National Institutes of Health. “There’s the collision of people who want to get tested who have symptoms and the people who don’t. We need to test large numbers of people who are asymptomatic, and we need to have alternate pathways to do it.”

Fortunately, quicker tests are on their way. The NIH’s Rapid Acceleration of Diagnostics (RADx) initiative seeks to speed up the development of tests. In April, Congress allocated $1.5 billion towards the program; last week, RADx announced the seven tests that passed the preliminary round of vetting and will now be produced en masse.

Each of the seven tests works a little differently. Four of them are lab-based, so would require end-users to collect samples and send them off to be processed, but have different ways of determining if the virus is present than the lab-based tests currently in use that allow them to speed up the testing process. The other three are called point-of-care tests and can be administered anywhere, including homes, offices, and airports.

The user inserts a sample into the machine, and gets results within 15 or 30 minutes, depending on the test. Some could be used to diagnose Covid-19 in hospitals or doctors’ offices. Many of the techniques—microfluidics, RT-PCR, next generation sequencing, and others—have been used in labs for years, as Tromberg points out, but haven’t made it into commercial diagnostics until this urgent need. The goal will be to increase the number of tests from 800,000 per day to at least 6 million by the end of 2020.

More widespread testing would also hopefully make the tests cheaper for end users; Tromberg, who also leads RADx Tech, said several of the RADx tests would likely cost about $20, with assistance from federal and state governments. The average coronavirus test currently costs about $100.

Increased testing could be an important way to get the US to some version of normalcy, says David Hutton, an associate professor of health management and policy at the University of Michigan. “I can imagine some situations where these tests could lead to ‘bubbles’ of ‘normalcy.’ Maybe an office building would test everyone who comes in. So, once you are inside, you would feel safe to interact normally with everyone in the building,” he says.

But 6 million tests per day is only about 2% of the US population, he points out, “so this isn’t quite enough for us all return to normal. But it could be helpful for those ‘bubbles’ and, if integrated with contact tracing and quarantine, could also help the rest of the community outside these bubbles.”

Though RADx’s vetting process has pushed companies to make tests more sensitive, accurate, and inexpensive, the tests will still need to receive emergency use authorization from the US Food and Drug Administration (FDA) before they can be deployed.

Nor are these seven the only rapid tests that may become available in the US; several private companies, such as Color Genomics and BD, have their own rapid tests already authorized by the FDA that didn’t go through RADx. RADx also anticipates adding more tests.

RADx’s lab-based tests could start to boost the US’s testing capacity as soon as September; other tests might take longer to get into users’ hands. “The more point-of-care the tests are, the more innovative they are, the longer it takes [to produce them in large numbers],” says Tromberg.

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