Finally, Another Weapon Against Covid
Good public health policy is welcome, even when long delayed. So we should cheer the Biden administration’s announcement earlier this month that Covid-19 rapid-result antigen tests (RATs), which tell you in as little as 15 minutes whether you’re infected, will be covered by private insurance. For uninsured Americans, the government would make 50 million free tests available, to be distributed through health clinics and other sites in rural and underserved communities. Assuming that they can detect the new Omicron variant along with its predecessors, these tests will be a critical part of our evolving pandemic strategy.
Nevertheless, the plan still faces hurdles. Supplies of the tests are limited, and even when they can be found, they’re expensive: typically, $10 to 15 apiece at drugstores. The administration’s plan to route reimbursements for the tests through private insurance is also unwieldy, requiring consumers to pay first, submit receipts, and then wait to get reimbursed. By contrast, in Germany and India tests are available in stores for a few dollars, and the U.K. provides seven free tests per day to anyone who wants them. Singapore mailed test kits to every household.
Widely distributing tests is important but insufficient on its own. We also need a massive public education campaign to teach people not so much how to use the tests (they’re easy to use), but when to use them. The goal of properly timed testing is simple: to minimize the time that a contagious individual is in the presence of others. (That’s especially important, given the high transmissibility of the Omicron variant.) Put another way, RATs enable you to determine whether you’re infected and able to spread the SARS-CoV-2 virus, so that you can self-quarantine and consider taking one of the oral or intravenous Covid-19 medications if you are. This requires people to act responsibly—that is, to test frequently—at times and places of their own choosing. The process is fairly painless, not unlike brushing your teeth or showering before you go out.
RATs identify individuals who are in their three-to-five-day period of maximum contagiousness, mostly before they are symptomatic. The tests generally involve putting a nasal swab and some reagent drops on a test card or test cassette that quickly displays two lines for positive or one for negative. Results are available in 10 to 30 minutes, in contrast to the slightly more accurate PCR tests, which measure viral RNA but take days to report results. PCR tests are useful to track progress over the entire course of infection, while RATs lose sensitivity once the contagious period is mostly over.
In simple terms, the rapid antigen tests enable you to be reasonably sure you’re not a risk to others before you leave for any get-together, movie, indoor sporting event, trip to a crowded store, and so on. They can prevent or mitigate large super-spreader events, such as occurred in August in the U.K., where, despite some (poorly enforced) vaccination and testing requirements, 4,700 people were infected, presumably with the Delta variant, at a music festival attended by about 50,000 people. A more recent super-spreader event occurred at a Wisconsin wedding celebration, after which more than a dozen “risk-averse” and “super responsible” wedding attendees went home infected with SARS-CoV-2, many by the Omicron variant. They included 11 people who are employees of Kaiser Permanente in the San Francisco Bay Area, some of whom went to work before learning they were infected, causing potential exposure of the virus to dozens of other employees and patients at two hospitals.
The tests would also be useful for schoolchildren or teachers exposed to a case of Covid-19, by converting “test and quarantine” while awaiting the results of the PCR test to “test and stay” if the result is negative.
This flow-chart illustrates the process for a hypothetical dinner gathering:
Why are we only now exploiting the benefits of RATs? The first problem was in getting emergency-use regulatory approval (final approval remains a bottleneck). Manufacturers submitted RATs to the FDA as a medical test, so the agency evaluated their accuracy in comparison with the PCR test. Since a RAT is accurate only during the initial onset and contagious period, it clearly fails the comparison test of equivalency. But “equivalency” is not the relevant benchmark when using RATs as a public-health measure rather than being used primarily in medical testing and treatment. Moreover, there was confusion over whether medical insurance could or should cover the cost of RATs. Untangling this bureaucratic knot led to delays in reaching the market. Hence, the (unreimbursed) low volumes of use meant that efforts to lower the cost slowed to a crawl, and the tests were (and are) not optimally used.
However we choose to do it, we need to get plenty of these RATs into the public’s hands with a well-communicated plan of action, so that we can finally put an end to the pandemic.
Henry I. Miller, a physician and molecular biologist, is a senior fellow at the Pacific Research Institute. Andrew I. Fillat spent his career in technology venture capital and information technology companies. He is also the co-inventor of relational databases. Miller and Fillat were undergraduates together at M.I.T.