Rapid Testing and Pooled Testing

How to safely return our children to school is the biggest debate of this pandemic summer. The stakes are high; many workers can’t return to their jobs and our economy will continue its descent into collapse as deficits pile up. If schools set off massive outbreaks in the fall, we will have to endure a second lockdown that may be even more damaging than the first one. One approach to prevent this is to rapidly expand cheap paper-based tests that can cost as little as $1 with a turnaround time of just 10 minutes.

Canadian biotechnology companies have the technology to produce these tests. However, they have not been approved by Health Canada because of their relatively low sensitivity, which is based on an outdated understanding on how COVID-19 is transmitted. 

The current gold-standard test is a PCR (polymerase chain reaction) test that is highly sensitive; such tests are expensive and extremely, perhaps too, accurate. Each test takes time and requires expensive equipment; they also cost $150 each and have long turnaround times — as long as nine days in the United States — because of a global lack of testing reagents, swabs and other supplies. Such delays make testing, isolation and contact tracing nearly useless, as you could be spreading the virus during the time you are waiting for results. 

In a recent landmark paper, Prof. Michael Mina, an assistant professor of epidemiology at Harvard University, shows that cheap paper-based tests are the best way, short of a vaccine, to return to some normal functioning in workplaces and schools. Asymptomatic transmission of COVID-19, especially in children, is not going to be picked up by our current testing system, nor will it be picked up by temperature screenings, a near useless measure some school boards are counting on to screen students. By the time most people get tested after experiencing some symptoms, they have usually been infectious for a week. The frequent use of at-home or at-school paper-strip tests would mitigate the transmission problem and the need for contact tracing.

It works like this: you use paper testing strips similar to a pregnancy test. On these strips are printed antibodies that react to the Sars-CoV-2 virus. Each student spits on a test strip every morning of school, and waits 10 minutes for the result. Positive students are sent home and their close contacts are screened by contact tracers. Even if the test misses occasionally, since you’re testing daily, we will eventually pick them up the next day or the day after.

How is this different from current testing? If paper-based tests are like binoculars, current PCR tests are like the Hubble telescope. They will find even the tiniest amount of virus fragments, often days before you are infectious and for weeks after you’ve recovered and can’t transmit to anyone. Paper-based tests detect massive quantities of virus in your body, around the time when you are infectious and have enough virus in your bloodstream and body fluids to transmit to someone else. You could show no symptoms at all, and could be spreading COVID to your loved ones, classmates or work colleagues without knowing.

The technology exists, and U.S. companies such as E25Bio, Sherlock Biosciences and Mammoth Biosciences are already making these tests. They need Health Canada and FDA approval, and even more importantly, the attention of our decision-makers to rapidly scale this technology up in time for school in September.

The benefits of paper-strip tests are immense. They have the potential to restore our daily life to pre-pandemic times and keep the economy afloat while preventing a second virus wave. Students could test themselves every day and show their negative tests as they enter the school, while those who test positive can confirm their results with a PCR test as they self-isolate. This system can also apply to people going to work, bars, malls, restaurants, movie theatres, gyms, etc. We cannot afford to ignore this technology, and with only weeks before the start of school, policy-makers need to act quickly.

Dr. Kashif Pirzada is an emergency physician in Toronto and the co-chair of the community group Masks4Canada. Wendy Wang is an applied life sciences student at Lakehead University.