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Still can’t get a coronavirus test? You’re not alone. More than two months into the outbreak into the United States, it still seems that tests are in short supply for the average Joe or Jane – despite promises to open drive-through testing centers and celebrities getting tested through their doctors. Here, we break down some of the reasons why tests are in such short supply. 

What exactly is in a coronavirus test that you’d get at the hospital?

The tests being used by the majority of testing sites, hospitals, and doctors’ offices are what’s called a polymerase chain reaction test, or PCR. A PCR test looks at samples of a person’s RNA – usually taken from the nasal cavity, in the case of coronavirus – to look for virus genes in the sample. Both the tests certified by the WHO and the CDC are PCR tests. 

Serology tests, which you may have heard about, differ from  the PCR test you’d get at a hospital right now. Serology screens use a blood sample to test for antibodies to see if someone had coronavirus in their system, while a PCR test looks for an active infection. 

PCR is not a new technology – it’s one of the most common ways to test for sexually transmitted infections. So why are we having such a hard time getting everyone tested?

Why are these tests in such short supply?

The tests take time, labor and materials to complete. As the world tries to ramp up its response to the pandemic, many of the key ingredients of the test itself – like swabs and special chemical reagents – are now in short supply. 

There’s a worldwide scramble for testing components – it’s not just a problem in the United States, Nick Vyas, executive director of the Center for Global Supply Chain Management at the University of Southern California’s  Marshall School of Business, told ClearHealthCosts. But Vyas says the United States approach to healthcare, and the federal government’s lack of response to the coronavirus, could cause testing shortages to be felt more sharply here.

“Some countries choose to take centralized command and control, meaning [the] federal government took control of the national purchasing, distribution, execution and managing the demand and supply and demand,” Vyas said. “We opted not to do that. We opted to completely keep our hands off and allow individual hospitals, groups, HMOs, cities, counties, states, to start to figure out on their own. And what it did it further amplified the problem of everyone going after the scarce commodity.”

Because there’s no central nervous system organizing a buying and supplying effort, Vyas said, American hospitals and cities are having a harder time on the ground finding supplies. 

Some of these things seem really simple – why are we facing a shortage?

Let’s take the swabs used for coronavirus PCR tests – what’s stuck uncomfortably far up patients’ noses to collect a sample. These aren’t just Q-tips you can buy at CVS. Medical-grade swabs for coronavirus testing need to be sterile, with flexible shafts that can reach far back in the nasal cavity. They also can’t contain calcium alginate, a common compound in swabs used for skin injuries.

Still, swabs feel like a no-brainer – they’re incredibly cheap, shouldn’t we have enough? – but they’re clogging up the testing pipeline. “The biggest problem in the last couple of weeks has been how to get the 10-cent swab to put into somebody’s nose to get that sample out of somebody and into a test,” Michael Mina, assistant professor of epidemiology at Harvard T.H Chan School of Public Health, said in a webcast in early April. 

The federal government is aware of the blockage. In an attempt to make swabs more widely available, the FDA said on April 16 that it would expand materials that are allowed to be used in medical grade swabs, and would work with cotton producers to create a new model that would help increase the number of swabs available.  

A look at the manufacturing pipeline for swabs can help explain what’s been holding up production so far. Puritan Medical Products Co., which is based in Guilford, Maine, is the market leader – it produced more than 30 percent of revenue in the global market in 2016.

In March, owner Timothy Templet told the Bangor Daily News that the company was producing up to 1 million swabs for covid-19 testing each week, fielding constant calls from hospitals and distributors alike.

The company only has 300 employees working in its factory, and while Templet says raw materials aren’t an issue, it has struggled to find time to hire more skilled workers to operate its machinery to keep up with the growing demand. Puritan has asked employees to come in on weekends and are operating 20 hours a day.

“It’s been staggering,” Templet. “It’s just staggering: the call volumes, the purchase-order volumes, the conversations with many government agencies and the higher-ups in the big distribution chains.” 

One of the companies that did produce swabs was in Lombardy, Italy, where the pandemic has shut down big parts of the economy.

Private companies, meanwhile, say they are eager to provide solutions to the swab bottleneck. There are a number of efforts to address the problem; it’s hoped that some or all of them will bear fruit. 

For example, one 3D printing company, Origin, says it has pivoted almost entirely to making medical supplies, and says it has successfully completed a clinical trial for its new swabs. The company is also part of a consortium of medical centers, universities and 3D printing companies who say they intend to collaborate on swab manufacturing.

“The demand for test kits is so huge that not one manufacturer would be able to supply all the demand,” Finbarr Watterson, Origin’s director of marketing, told ClearHealthCosts. “For this reason the companies and organizations involved decided to pool their resources, connections, experience together in order to collaborate, learn from each other and move extremely quickly. It would take a single supplier many months if not longer to achieve the same result.”

What about the other missing elements?

Like swabs, other key components of the coronavirus PCR test are also facing shortages in their supply chains. 

Once a sample is collected with a swab, it needs to be put in a tube of chemicals that will help it stay stable before it reaches the labs – what’s known as viral transport medium, or VTM. Many labs around the country said in March that they were not only running low on swabs, but also on tubes of the VTM. Other medical professions have attempted to crowdsource VTM stockpiled in offices – the American Academy of Dermatology put out a call to its members to donate VTM, which dermatologists use to test for herpes and other infections, to local labs, hospitals or their public health department. The FDA has since expanded the regulations for what types of VTM can be used for collection.

Some testing labs say they have run dangerously low on chemical reagents – the materials used in the lab to produce the chemical reaction to read test results. The New York Times reported in early April that demand for reagents in Western countries had skyrocketed – to the point that international suppliers have little supply to offer other countries who are now getting hit with the virus – while the Wall Street Journal reported that some labs had resorted to mixing their own homemade reagents.

“There’s never really been a shortage of chemical reagents before now,” Doris-Ann Williams, chief executive of the British In Vitro Diagnostics Association, told the Times. “If it was just one country with an epidemic it would be fine, but all the major countries in the world are wanting the same thing at the same time.”

Producers of specialized reagents to isolate RNA in the lab from collected samples, which are sold in kits, are also ramping up supply to avoid a shortage. “To give you an idea of the scope: as of mid-March 2020, we already shipped twice as many RNA [extraction kits] to the United States as we did in the entire year 2019,” a spokesperson for Qiagen, one of the world producers of RNA kits, told FastCompany.

What about other supply chains?

It’s not just shortages in testing materials that are worrying experts. Vyas says that he and other supply-chain experts are keeping an eye on much more basic things – like the food supply.

Folks who have been to a grocery store in the past couple of weeks know that some normal food staples are nowhere to be found. Key meat processing plants around the country have shut down as hundreds of workers have gotten sick – including a plant in South Dakota, which provides 18 million servings of pork per day and has seen almost 300 workers test positive for covid-19. Experts say that the increased demand for meat in grocery stores and the dwindling demand for meat sold to schools and restaurants is creating a lopsided effect.

How does this loop back to false negatives?

As we wrote earlier this month, a negative covid-19 test result doesn’t mean a patient doesn’t have the virus. 

Experts still are not totally sure what the rate of accuracy is for the coronavirus PCR test. Most PCR tests, like all medical tests, have a failure rate that scientists and doctors accept as par for the course. But a false negative on a flu test is far less of a public health risk than a false negative on a coronavirus test.

Also, there are a number of tests — the FDA has approved dozens for use, and it seems obvious that some would be better than others. Here’s a list of approved tests.

A helpful tool for doctors wondering about false negatives would be the ability to give multiple tests to the same patient, which would give a wider margin for error, but the scarcity of tests is not allowing for this at most hospitals. Most experts agree that ramping up testing is a major requirement for reopening the country and slowly bringing life back to normal. 

If only we had enough swabs.

Molly Taft

Molly Taft is a  staff writer for Earther, Gizmodo's climate change blog. Her writing has appeared not only at ClearHealthCosts,...