All of the responsible plans for loosening economic and social restrictions call for widespread testing capabilities at the community level. Testing in the US has thus far been an epic failure, and there is no particularly good news on the horizon. Clearly the greatest return on investment for the next few weeks, and likely the next few months, would be generated from substantial governmental investment in scaling up testing and making it available to everyone as soon as possible.
We need two kinds of tests: 1) those that will tell you if you have an active infection and are contagious, and 2) those that tell you if you’ve been infected and developed antibodies, and are therefore likely to be immune. With a disease as stealthy as Covid-19, it’s not hard to imagine why both are critically important.
The trick to effectively managing Phase II at the community level is to closely monitor the Effective Reproductive Number, or Re–the number, on average, that each contagious person infects. If a community can keep Re below 1, it can contain the spread of the virus, but with asymptomatic infectious spread, which is a feature of Covid-19, the only way to know that is through testing. And to be effective, the test must generate results quickly.
A fast turn-around test for active infection–ideally one that could be administered on-site and generate results in minutes–would enable employers to test employees every day, and it would allow communities to enact the kinds of test-trace-isolate strategies that have proven successful in places like Singapore and South Korea. Until we have it, loosening restrictions would likely just lead to a subsequent period of geometric spread.
Antibody tests that show probable immunity are also important in the case of Covid-19 because we don’t have a clear idea of how many people have been infected and recovered. There have been too many asymptomatic or mildly symptomatic cases, or cases that have been confounded with the flu, common colds, or allergies. Theories are rampant that Covid-19 has already spread widely in some communities before it became part of the national consciousness. These tests would help us know what the true case fatality and hospitalization rates are, and they would also let each community how far it has proceeded in the direction of herd immunity. Perhaps best of all, it would all let individuals know if they are safe to venture outside and into public venues again.
The economic return to quickly developing and delivery effective testing at a truly national scale would be measured in the hundreds of billions, if not trillions, of dollars. The federal government has already failed its citizens in not ensuring adequate testing prior to the outbreak. We can only hope it isn’t continuing its incompetence now.