All of Us

The Strategy of Rapid Testing

by Michael J. Critelli

As the Covid-19 crisis remains out of control, the American public is obsessed with three questions:

  1. What are my chances of getting infected or infecting others?
  2. If infected, what are my odds of dying?
  3. What can I do right now to protect myself and my loved ones?

People can wear masks and minimize their viral load exposure as a response to the 3rd question. And clinicians are improving risk prediction. But we're a long way from the kind of predictive diagnostics we need.

The testing protocol is fundamentally flawed. At the individual and population levels. We have no idea who's infected or our odds of infection or death. This causes fear, stress, anxiety, and mental illness.

We need two strategies:

  1. Pooled testing (e.g. waste water analyses for cities, campuses, and, buildings) to determine the population's infection rate.
  2. Rapid point-of-care testing to supplement the lab test to detect infected people.

Rapid point-of-care diagnostic Covid19 testing can be at an outpatient clinical setting or at home. Eventually, non-medical personnel will follow a standard testing protocol.

The goal is to avoid delays and handling risks, and to minimize costs by testing where the samples are collected.

Abbott Labs BinaxNOW Covid-19 test, is a $5, 15-minute rapid test that received market approval in August.

Dr. Michael Mina is from Harvard's T.H. Chan School of Public Health. He said that the most credible testing strategy is frequent, inexpensive, rapid-response, at-home testing with a paper strip.

He advocates it because:

The strength of this system is that it would actually abrogate the need for contact tracing... If your goal is not to have a heavy hand over the population (implementing onerous public-health restrictions on businesses and recreational activity), this is the way to do it, because it strips away ‘all of that complexity.’ Most people who test positive will have done so before they become infectious, and can easily self-quarantine for the six days or so until they cease being infectious.

By contrast, the current testing protocol touches too few of us, takes too long for results, and may catch people so late in the infection process that it delivers a positive result when they are no longer at risk to themselves or others.

Additional vendors are seeking FDA approval for rapid tests. On December 15, the FDA approved an Emergency Use Authorization for the Ellume COVID-19 home test. This is a rapid, lateral flow, antigen test.

The FDA also approved Lucera, at-home rapid testing on November, 17.

And breathalyzers can detect the presence of the virus within 15-30 seconds. These tests are between 85-90% effective. They used different approaches that don't overlap.

If the data were collected from tests over several days, the amount of data required for ~100% certainty would actually decline. Confidence levels would increase as data from the two testing methodologies are combined.

Other testing methodologies require a saliva sample. The saliva needs to be analyzed in a lab. Eventually, this could be a viable 3rd independent rapid testing method.

Vaccines have started.  Antiviral therapies and convalescent plasma are on the horizon. But we need to know our true risk level. This will give us greater peace of mind. And a more realistic ability to protect ourselves in the meantime.