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The pandemic winner: Will It be Sweden or New Zealand?

The world has never conducted a human-centered natural experiment of a biological threat of this scope before. Three billion people in over 80 countries (including UK, France, and most U.S. states, among many others) are in some form of lockdown with over 185 countries having reported three million-plus Covid-19 cases. 

Yet in countries such as Sweden, elementary schools, businesses, and restaurants are open, and in Belarus, the president is seen at hockey games and declares business-as-usual.

To paraphrase Deng Xiaoping’s formulation from the 1980s, we see the spread of “one virus and at least two systems.” 

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Governments everywhere are facing a stark “jobs vs. deaths” Hobbesian choice. 

How long will the public tolerate lockdowns that paralyze the economy and limit essential social mobility?

In response, many countries are seemingly lining up behind two unproven strategies based on contradictory hypotheses of virus behavior. This with similar hopes that they can thread the needle by limiting the human toll to “acceptable” levels, keep hospitals from being overwhelmed, and maintain vital economic activity.

The first “elimination hypothesis” has been implemented on physical or virtual islands such as Singapore, Taiwan, South Korea, Iceland, and New Zealand. It is based on the presumption that the virus can be eliminated via a two-pronged strategy: stop importation at borders and ports of entry and reduce domestic outbreaks by stringent containment procedures.

In countries such as the U.K., the U.S., Italy, and Spain, where the virus has long ago escaped containment and mitigation phase, a variant of the elimination model is being deployed. Cycles of suppression lockdowns alternating with the relaxation of social distancing interventions accompanied by aggressive containment measures are anticipated. 

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Significant second and further resurgent waves of infection are likely if the importation of virus or domestic foci re-emerge. Armies of virus hunter tracking teams would need to be deployed in ongoing containment firefights.

The public messaging accompanying the elimination model is for absolute safety to avoid exposure at all costs. Acquired immunity is thwarted, and an effective vaccine features prominently as the end-game.

The second “herd immunity hypothesis“ is actively or implicitly practiced in Sweden, Mexico, and Belarus. It assumes a virus that cannot be sealed off or contained. It is presumed to be best controlled through managed spread through the population, leading to progressively greater levels of acquired immunity. Since the virus cannot be indefinitely evaded, it is accommodated and gently accepted. It was initially slowing then ultimately halting the spread through herd immunity.

Which of these mutually exclusive hypotheses is correct? The World Cup teams are now on the field, and real-world experience is being developed, albeit at an agonizingly slow pace. 

It now appears that the virus is more easily spread but far less lethal than previously assumed. There is a large (25-50 percent or higher) asymptomatic and mild disease rate.

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The mortality under age 65 without pre-existing conditions is one to two orders of magnitude lower than in those over age 75 and vulnerable. These observations strongly favor progressive herd-immunity rather than elimination as the winning strategy. But we must protect and not sacrifice those vulnerable and health care providers in the pursuit of this goal. Viral behavior is not conducive to successful elimination. Second wave resurgence in Wuhan China, Singapore, and Japan are consistent with this conclusion.

As these grand experiments play out, it would be a tragic missed opportunity not to take full global advantage. Each country should make explicit the assumptions and presumed scientific basis of its strategy clear. To allow valid national comparisons, there should be a cooperative global “Big Data” acquisition and analysis framework set up to measure the impact of each strategy.

This race is more marathon than a sprint. Long-term health winners will be judged on the cumulative “area under the epidemic curve” measured in total infections, severe cases, and deaths. Also, when measures of effective immunity are eventually determined, population immunity rates will be critical. If the herd-immunity hypothesis is correct, the early numerical lead of the elimination countries will dissipate over time.

Perhaps the biggest challenge facing governments is maintaining public trust. The inherent conflicts between the “elimination” and “herd-immunity” models have profound implications for public risk perceptions. Is exposure to be ubiquitously feared and avoided or accepted and even welcomed as a necessary protective measure? Absent evidence-based information, ongoing polarization through ideological and political lenses with attendant fear, anxiety, and confusion is likely.

In this analysis, the early pandemic World Cup handicapping predicts herd-immunity Sweden over elimination New Zealand. A pressing question to avoid treacherous and seemingly endless overtime: are we prepared to learn from each other in charting a course for collective benefit? 

Steven Phillips, M.D., MPH, is a medical epidemiologist and pandemic preparedness practitioner formerly with the Centers for Disease Control and Prevention.