But without detailed federal guidance, states and cities remain divided, and some of them stifled, on how to best to use those types of rapid tests and others for the testing technique known as “screening.”
Screening involves routinely testing people whether or not they have symptoms. Because an estimated 40% of coronavirus infections are asymptomatic, according to the Centers for Disease Control and Prevention, the idea is to focus on groups, such as those in nursing homes, schools or higher-risk workplaces, and use point-of-care tests or other techniques to test everyone in those groups and isolate the infected. Epidemiologists say communities should implement screening to limit outbreaks.
New Orleans Health Director Dr. Jennifer Avegno said she has been working with local officials on a plan that would allow for routine testing of teachers in her city, but without overarching federal guidance, she said, “It’s been very challenging as a local health leader to communicate what we believe to be best practices.”
“What we don’t have is a national strategy that we’re actually implementing to get those asymptomatic screening tests to everybody who most needs them right now to reopen schools safely, to reopen the economy as effectively as possible,” said Dr. Mark McClellan, a former commissioner of the Food and Drug Administration under President George W. Bush and the Duke-Margolis Center director.
Admiral Brett Giroir, who oversees federal coronavirus testing efforts, said last Thursday he has “never been told to slow down testing” and said that he supports asymptomatic screening efforts.
A spokesperson for the Department of Health and Human Services, Mia Heck, said in a statement that the administration is continuing to aggressively invest in point-of-care testing, that allotments of the Abbot antigen tests to states will begin this month, and that “the public can expect additional guidance on screening to be forthcoming.”
Heck added that the federal government awarded about $10 billion to states, territories and local governments to support their testing plans, and that those funds are still largely available for states to draw upon.
What the tests are needed for
That number marks exponential growth since the start of the pandemic. But the nation’s testing infrastructure has primarily been wielded for diagnostic purposes — meaning PCR tests, which are known to be highly accurate, have been used to determine whether individuals who feel sick or think they have been exposed to the virus are actually infected.
A. David Paltiel, a professor at the Yale School of Public Health, argues that in order to use testing as a tool for outbreak control as opposed to individual diagnostic purposes, communities must frequently test groups of people in order to catch asymptomatic spreaders.
In a study that examined the spread of the virus among a hypothetical cohort of students, Paltiel found that screening people every couple of days with a less sensitive test was more effective for controlling an outbreak than using more sensitive tests less frequently.
“The most important variable was frequency … and again, the reason frequency matters so much is because of these silent spreaders,” said Paltiel, who said rapid, point-of-care antigen-based tests could prove more effective for catching asymptomatic cases within groups even though they are less sensitive than lab-based PCR tests because they are faster and cheaper.
Moreover, recent comments and guidance from the Trump administration have created questions and confusion around asymptomatic testing in general.
States offering tests, but different strategies, limited resources
Thirty-four out of 37 states and Washington, DC, told CNN they still recommend or offer tests to people who have been exposed to Covid-19 and are asymptomatic.
Oregon recommends people exposed to the virus quarantine for 14 days and get tested if they develop symptoms. Rhode Island said each situation is managed on a case-by-case basis.
Florida’s Department of Health said people who are in brick-and-mortar schools or other congregate settings and develop symptoms should get a Covid-19 test. The department said Florida follows CDC recommendations that testing “should be considered” for asymptomatic close contacts.
But when asked about screening strategies and whether they are planning to use rapid tests like point-of-care antigen tests for such methods, state health departments offered a wider range of responses.
The Vermont Department of Health is conducting routine, facility-wide testing at correctional and congregate care facilities but using lab-based PCR tests to do so, according to a spokesperson.
Others said they need more information, especially on antigen tests.
“At this time, we do not have all the specifics on these tests, including their strengths and weaknesses and where they would be most useful,” a spokesperson for the Montana Department of Public Health and Human Services said of antigen tests.
Avegeno of New Orleans said the city is currently evaluating the feasibility of testing teachers each week with PCR tests, but because they are expensive and cheaper antigen tests are not yet available on large scale, funding is an issue.
While county and city health departments have begun thinking about asymptomatic screening, ongoing case surges coupled with limited guidance and resources have kept many from proactively implementing screening strategies, said Lori Tremmel Freeman, CEO of the National Association of County and City Health Officials.
“It’s really hard to move forward when you’re stuck in place,” Freeman said.
Efforts to move ahead
Some private organizations and universities have taken it upon themselves to launch screening plans.
Rebecca Lee Smith, an epidemiology professor at the University of Illinois who helped develop the program, says such strategies implemented nationwide, along with consistent messaging, could curtail the virus’ spread, but she sees limited federal leadership.
“It is quite frustrating,” Smith said. “National messaging is essential to controlling infectious disease because diseases don’t stop at state borders.”
Blythe Adamson, an advisory council member for Testing for America, a nonprofit formed by scientists and entrepreneurs to help address the testing crisis, said a strong national plan that prioritized certain groups for screening would not only have health benefits but could accelerate economic recovery.
She clarified that she is not calling for all Americans to be regularly tested, but she said the government could help identify pockets of the economy that would benefit most from asymptomatic screening and potentially offer incentives, like tax subsidies, to certain employers that implement screening.
“We’ve got so many software engineers but is it cost effective to test them all when they can all be working from home? Or is it better to regularly test lower-wage retail workers because we want these retail locations to be open and safe and productive?” Adamson said. “Government intervention can help guide the most efficient use of the resources we have available today.”