Famously or infamously, depending on how you look at it, Sweden imposed relatively light governmental restrictions on businesses and personal activity in the wake of COVID-19. So far the country has paid for that with relatively more deaths (per capita) than its neighbors (Norway, Finland, Denmark), although Sweden has sustained fewer deaths than various other countries (United Kingdom, France, Spain, Italy).
Colorado took quite a different approach as we endured a statewide “stay at home” order for a month. Colorado did “flatten the curve,” limiting deaths to 777 by the end of April, or 135 deaths per million. That compares to 184 deaths per million for the United States, 244 for Sweden, and 525 for Spain. On the lower end, the island nations of Japan, New Zealand, and Australia each suffered between 3 and 4 deaths per million, while Germany suffered 75. South Korea, known for its aggressive testing and contact tracing, suffered 5.
Now Colorado is transitioning to “safer at home,” although multiple counties extended stay-at-home orders through May 8. As restrictions loosen, most businesses can again open, albeit with distancing, hygiene, and capacity restrictions. “Gatherings in both public and private spaces of more than 10 people are prohibited,” which rules out many sorts of social and economic activities (large in-person church services, live concerts, team sports). And nightclubs, gyms, and spas remain closed.
Colorado’s restrictions remain substantially more severe than Sweden’s, but they have moved closer to those of Sweden. In addition to strongly encouraging Swedes to practice social distancing, Sweden restricted capacity in stores and on public transit, limited public gatherings to 50 people, and (as health minister Lena Hallengren said) “implemented distance and online education for upper secondary schools and higher education.” Both the governments of Colorado and Sweden have raised the possibility of stricter lockdowns if the disease spreads out of control.
More significantly, Colorado seems to be following Sweden’s model of seeking to keep spread of the disease within hospital capacity without trying to tightly contain spread of the disease to a small minority of the population. Is that a good idea?
Arguably it is too early to evaluate Sweden’s relative success or failure simply because the pandemic has not played out yet. Sweden chose to take its lumps early, and other regions might take their lumps later, either with new surges of infection or with more economic destruction, which itself is life-threatening.
A country or region faces two basic alternatives here: 1) limit spread of the disease such that it infects a minority of the population or 2) reach herd immunity. The first outcome can be achieved mainly through a combination of social distancing (which involves partly shutting down the economy), improved public hygiene, and testing with contact tracing. Countries that have more testing and tracing don’t need as much social distancing.
Regardless of the particular mix of tactics, keeping the disease in check requires a robust response, and this must be kept up indefinitely, until a vaccine becomes available. Maybe that will be later this year, maybe next year, maybe four years from now, maybe never. If a country wavers in its response, the disease will surge again. A country might at some point choose to relent and let the disease spread, whether because an effective cure comes online, a less-harmful strain of the disease becomes dominant, or people no longer can live with the restrictions.
Reaching herd immunity is a rough way to eventually slow the spread of the disease. The advantage is that, once a region reaches herd immunity, the crisis basically plays itself out. At that point COVID-19 stays around, but the virus never actively infects more than a small fraction of the population at once. The disease then can be managed indefinitely with minimal resources.
Sweden may or may not be on the path to herd immunity. Swedish authorities think that around a quarter of the population already has been infected. Anders Tegnell, chief epidemiologist at Sweden’s Public Health Agency, offers a mixed message on this score. He told USA Today, “We could reach herd immunity in Stockholm within a matter of weeks. . . . We believe herd immunity will of course help us in the long run, and we are discussing that, but it’s not like we are actively trying to achieve it as has been made out.” He says the goal has been “to keep the transmission rate as low as we can,” but this is within the context of what Swedes regard as “reasonable measures,” and herd immunity may well be the outcome.
A country can reach herd immunity in a quick and disastrous way, such that the disease blows out health care capacity and many additional people die due to lack of adequate care, or in a slow and controlled way, such that hospitals never become overloaded.
Sweden’s strategy in this regard, as outlined in an April 6 document, sounds exactly like Colorado’s strategy. Sweden’s “overall objective” is “to ‘flatten the curve’ so that large numbers of people do not become ill at the same time.” Colorado governor Jared Polis has taken almost exactly this position of Sweden: “The measures taken by the Government and government agencies to reduce the pace of the virus’s spread need to be weighed against their effects on society and public health in general.”
Notice what Sweden’s “overall objective” is not: to restrict spread of the disease to a minority of the population. If that happens, great, but it’s not the aim.
This also perfectly describes Colorado’s broad strategy. In an April 27 document, Polis says the purpose of the stay at home order was to slow the spread of the virus, “buy time to build healthcare capacity,” and “buy time to grow testing capacity and obtain supplies.” Notice what is not on the list: restrict spread of the disease to a minority of the population. The means were different but the goals were basically the same.
The goal of “stay at home” was to “knock down the effective R0 [R-naught, or number of other people a sick person infects] as hard as we can and as quickly as we can.” The goal of “safer at home” is to “manage the spread” by keeping R0 “close to 1.” A related media release is more explicit: “Safer at Home is meant to provide a more sustainable way of living for Coloradans, while managing the spread of the virus to ensure our healthcare system has the capacity to manage an influx.” Goals include “managing the spread of the virus” by keeping R0 “between 2 and 1.”
To spell out the obvious: If Colorado’s effective R0 goes above 1 indefinitely, that simply means that Colorado will reach herd immunity, a possibility that Polis has explicitly discussed. There is no other possible outcome. The disease will continue to spread until a vaccine becomes available, and then we’ll reach herd immunity by getting vaccinated. Of course, if Polis can get an effective R0 of less than 1, I’m sure he’ll take it. But that’s not what the state is planning for. Incidentally, according to figures presented by Hassan Vally, Sweden’s effective R0 has mostly ranged between 2 and 1.
Even if Colorado goes down the path to herd immunity, there is a good argument for Colorado to try harder than Sweden did to keep its effective R0 relatively low. Here is a very important piece of the puzzle that I didn’t appreciate until Trevor Bedford explained it: The percent of the population that must be infected to reach herd immunity varies by the effective R0. In other words, if we did nothing to lower R0, not only would the disease spread horrifically fast, a substantially larger percent of the population eventually would be infected to reach herd immunity. A lower R0 slows the spread of the disease and also lowers the threshold for reaching herd immunity. Bedford suggests that reducing the effective R0 from 2 to something like 1.4 ultimately could save tens of millions of Americans from infection.
One way that Colorado can keep disease spread down is by expanding testing. Colorado has expanded its testing by over half, from 2,001 tests on April 22 to 3,475 tests on April 29 (this “may not include all negative results,” plus a backlog of tests was included with April 23 figures). But testing would have to expand many times that amount to reach the levels that Paul Romer calls for. Tomas Pueyo calls for testing people with symptoms as well as all their contacts, a strategy that would require very fast and effective testing and contact tracing. Hopefully Colorado can continue to do better on both testing and tracing, even as we improve our public hygiene and maintain sustainable levels of social distancing. As I’ve argued, if we’re going to reach herd immunity anyway, we might as well drastically lessen the pain of that through intentional, controlled, doctor-supervised infection—although this is a long-shot for political reasons.
The fact is that life is never going back entirely to what “normal” used to look like. The world spins on. We can resume basically normal life once we have a cure or a vaccine. Until then, we can live with a “new normal” by substantially reopening the economy while keeping the disease from running away from us.