National Post (National Edition)
Test potential carriers, not people already sick
Ideally, we would test everyone to know who is carrying coronavirus and isolate them to promptly stop the pandemic. But this won’t happen. Donald Trump is talking about soon having millions of people tested every day. I have my doubts, given the shortage of resources, both material and human, that would be required for that. But nobody believes the U.S. will be able to test tens of millions of Americans in a short time, let alone all 327 million. The same situation prevails across Canada. Within a reasonable time frame we won’t be able to test everyone for the virus. Far from it.
So who should we test to get the most benefit from the limited test resources we do have? If we can’t test large numbers of people, the question becomes: why waste scarce resources testing people who are already quite sick? If there is no treatment, what have you gained? Medically? Nothing. Statistically? Not much more.
Anybody who is sick with the cold, the flu, a gastro or the coronavirus should be isolated. This way, they won’t contaminate other people and strain the health system by taking resources away from the real crisis. Contaminating anyone with any disease at this point, not just the coronavirus, is bad. There is therefore no compelling need to test people in order to determine what they have. The prescription for all these suspected cases, as well as for others who feel sick, should be quarantine and self-isolation. If you become very sick, you go to the hospital, coronavirus or not. No need to test for that.
Asymptomatic people who are voluntarily self-isolating or in self-quarantine shouldn’t be tested, either. If you think about it, a true quarantine is the equivalent of administering yourself a homemade test and waiting 14 days for the results. And it’s not much different from what people go through who do have the test but wait more than a week to get their results.
What is really important, however, is to detect individuals with no symptoms who are roaming around our cities spreading the coronavirus, and to do so quickly. These mobile non-symptomatic individuals are the real threat — not the observably sick and not people confined at home. We already have a test for the sick: physical observation. And we have another for people willing to stay home: a self-revealing 14-day quarantine.
We have learned very little with the 100,000 tests we’ve given to people who were already sick. The tests on sick people have not revealed what we truly and urgently want to know: namely, how many people are infected in each province and who is still moving around, potentially infecting others. Small-sample random testing would give us the answer to the first question. A reversal of our current testing procedure to test only people with no symptoms who are not staying home would help answer the second.
In searching for something hard to find, we should put the scarce resources at our disposal on identifying the threat, not the damage it has already done. We should thus start testing as many people who are not sick and unable to stay home as we can. If we found that only 10 people out of 100,000 were carrying the virus, we could infer that the disease is not yet out of control in Canada and that our strict social distancing measures could be relaxed sooner rather than later. If, however, there were 1,000 coronavirus carriers or more per 100,000, then it might be urgent to use even more extreme measures to limit the crisis.
Testing workers in the health-care sector and in other essential jobs, including those brave enough to work all day with the public in pharmacies, food stores and supermarkets, might be an especially efficient use of our limited testing resources. Many health-care workers are in frequent contact with the sick. And those still working in essential services are more exposed to the virus and more likely to transmit it to coworkers and colleagues and family members, if they are unknowingly infected.
To further limit the number of the relevant population to target for testing and accelerate the identification of coronavirus carriers, we should also all designate the youngest or healthiest member in our family to go shopping. Anyone else should stay home if they can and be in charge of washing food and cooking, thus limiting their exposure.
Once we have more tests, designated family shoppers could also be given priority for testing. One limit of this strategy may be that people who are asymptomatic might have negative test results if the virus has not yet reproduced in sufficient quantities in their body. Underestimating the number of infected individuals could therefore give us a false sense of security. If this is the case, working on improving the accuracy of the tests at confirming the presence of the pathogen should also be a priority. In the meantime, finding invisible carriers is better than testing people who are already sick.