Can The U.S. Use Its Growing Supply Of Rapid Tests To Stop The Virus?
A new generation of faster, cheaper coronavirus tests is starting to hit the market. And some experts say these technologies could finally give the U.S. the ability to adopt a new, more effective testing strategy.
"On the horizon — the not too distant horizon — there are a whole series of testing modalities coming on line," says Dr. Ashish Jha, dean of the Brown School of Public Health. "And that gives us hope we can really expand our testing capacity in the nation."
Until now, testing has been primarily used to diagnose people who may have COVID-19 and any of their close contacts who may also be infected. But a stubborn shortage of the molecular tests most commonly used — and slow turnaround time for results — has hobbled the nation's ability to stop outbreaks and contain the pandemic.
That could change, argue Jha and other public health researchers, as new rapid tests — primarily antigen tests — become more widely available, enabling communities to start widespread screening of the highest-risk people.
"It is a paradigm shift," Jha says. "What I think new testing capacity allows us to do is actually play offense — go and hunt for the disease before it spreads to identify asymptomatic people before they spread it to others. It really becomes about preventing outbreaks — not just capturing them after they've occurred."
Jha and a team at the Harvard Global Health Institute have periodically evaluated how much testing the country and individual states need to effectively fight the spread of the virus.
In a new analysis the group completed for NPR, researchers developed daily testing targets, showing what would be needed to routinely screen large numbers of asymptomatic people. The researchers factored in the growing availability of the rapid coronavirus tests.
The U.S. would need 4.4 million tests every day, the analysis concludes, to reach what Jha calls "a basic level of proactive testing." The idea is to do regular testing of some of the highest risk groups — stopping outbreaks before they can spill over to the rest of the community.
This scenario calls for screening all nursing home residents and staff twice a week and weekly testing of every prison inmate and guard, firefighter, police officer and emergency medical technician, as well as teachers and staff in K-12 schools, and all university students.
Using the older molecular test technology, the U.S. has never managed to perform more than about 1 million tests per day. But the companies that make the new antigen tests are ramping up production and additional tests are in the pipeline. As a result, Jha and others estimate that there could be enough capacity to hit 4.4 million daily tests by the end of the year or early 2021.
But Jha and his collaborators say that far more testing is needed to really enable the economy to reopen safely. The analysis concludes that ideally, the U.S. would need just over 14 million tests a day.
That ideal scenario would allow communities to expand regular testing to most K-12 students that are in school (excluding those in communities with a high rate of infection, where schools would be closed) as well as health care workers, food service employees, cashiers and retail store clerks.
"We've been holding our breath as a country for the last months — waiting for a new technology, waiting for more capacity for testing," says Dr. Thomas Tsai, an assistant professor of health policy and management at the Harvard T.H. Chan School of Public Health who collaborated with Jha in developing the screening targets.
"This is a moment for us to capitalize on the technology and lets us reopen parts of the economy and schools with confidence," Tsai says.
Other public health experts agree.
"We're really at a critical inflection point," says Dr. Jonathan Quick, managing director of pandemic response preparedness and prevention at the Rockefeller Foundation. "We're on the verge of a dramatic scale-up of the rapid, point-of-care antigen tests that are vital for screening asymptomatic and presymptomatic people."
The foundation — which researched production capacity in the industry — projected that there could be capacity to perform more than 70 million tests a month by October, close to 200 million by January and more than 228 million a month by April. (That April figure would add up to about 7.6 million tests per day.)
"It'll let us open schools, keep them open and pick up outbreaks early in workplaces, and it will help keep our economy going, keep our education system going," Quick says.
Deciding who gets screened
The federal Department of Health and Human Services is buying at least 150 million antigen tests and recently detailed plans for how it plans to distribute them to states. At the same time, some states have started teaming up to buy large numbers on their own.
The key, however, will be to deploy the tests strategically to ensure that the people most at risk get them, Jha and his colleagues say. This is how they become an effective tool for preventing widespread community outbreaks.
"But what we're seeing, of course, is this is not necessarily how these tests are being used," Jha says, noting that professional athletes have been among the first to get access to the new antigen tests.
"Now, I love football. I think it would be great to have Big Ten football playing," Jha says. "But I would prioritize nursing homes and schoolteachers over Big Ten football."
This is why groups like Jha's have developed tools to help state or local leaders think through the tradeoffs involved in distributing tests.
Brown University School of Public Health and the Harvard Global Health Institute released a calculator tool Thursday that allows leaders to assess which groups they want to prioritize — and see how many daily tests they'd need to screen those groups regularly. The tool offers five scenarios: the base and ideal options shown below, as well as three intermediate options that focus on schools, health care or the economy.
Will there really be enough tests?
Some say the federal government should be doing far more to more quickly increase the availability of antigen tests, including even simpler versions — not yet on the market — that people could use at home like home pregnancy tests.
"They look a lot like the chlorine test you might dip in your pool or the test strips that you might test your water with in your kitchen," says Michael Mina, an infectious disease expert at the Harvard School of Public Health.
Mina has been urging the Food and Drug Administration to make it easier to get these tests approved, even if they're less accurate. And Mina argues that the Trump administration should invoke the Defense Production Act to take over production of these tests.
"If a foreign enemy was dropping bombs on the United States, they wouldn't just wait until the private sector came up with a new fighter jet. They do things very proactively," Mina says. "That's how we should be dealing with this virus."
But even if the tests become available in sufficient quantities and are deployed through a comprehensive strategy — two big uncertainties — there are many questions and deep skepticism among some public health experts.
"I don't see a monumental shift," says Jennifer Nuzzo, a senior scholar at the Johns Hopkins Bloomberg School of Public Health Center for Health Security who has been studying testing.
Nuzzo says it remains far from clear how quickly the companies making the new tests will expand capacity.
"The new tests are potentially useful, but they're still not available in enough of a quantity and at a low enough cost to blanket the country and be used in ways that some have suggested," Nuzzo says.
Concerns about accuracy and reporting
In addition, there are troubling questions about how reliable the new antigen tests are when used to screen large numbers of people. They tend to produce more false negatives and false positives than the existing molecular tests. And the tests have never really been carefully evaluated to screen large numbers of people without symptoms.
"We really don't yet know how these tests perform in people without symptoms. So there are cautions about using them in those populations," Nuzzo says. "We need to better understand how they work."
Supporters of widespread use of rapid tests acknowledge they may be less accurate in some ways. But the tests tend to be more effective at spotting infected people when they are most infectious, which is what's most important, the supporters say. And the tests' shortcomings could be outweighed by their potential to enable frequent, repeated testing, which means more positive cases can be identified overall, they say.
But another problem is many states are failing to capture and report the results of antigen tests, in part because many places using them, such as nursing homes and universities, often don't have efficient ways to transmit the results to public health authorities.
"There's a whole question swirling around that. There's a real worry there," Nuzzo says, because that could lead to some communities dramatically undercounting the spread of the virus.
"I don't think it's helpful to oversell optimism. I don't want to leave people with the belief that all the hard challenges are behind us. No one tool is going to lead us out of this pandemic," Nuzzo says.
Some public health officials say the lack of clear guidelines from the federal government about how best to use the tests has caused confusion.
"There are no clear guidelines on how to use these rapid antigen tests," says Dr. Jeffrey Engel, the senior adviser for the COVID-19 response for the Council of State and Territorial Epidemiologists. "What we're seeing is a hodgepodge of different usages across the country."
"It seems to be that HHS is concerned more about logistics and getting tests out the door and increasing testing numbers and less concerned about quality control and public health reporting," Engel adds. "It has the potential to be a big mess."
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