As we find ourselves in the second year of a global pandemic, the question on everyone's mind is: when will this end? Much of the narrative around the pandemic last year was that all hopes for a return to normal hinged on development of an effective vaccine. This rhetoric was deaf to the concerns of vaccine and public health experts, and for many a SARS-CoV-2 vaccine has become the magic bullet to deliver us from endless cycles of lockdown and economic decline. Against all precedent, going into 2021, the world had several vaccines with demonstrated efficacy against symptomatic COVID-19 in its armamentarium. Yet a magic bullet they are not.
Numerous issues and uncertainties surround the existing COVID-19 vaccines. We do not yet know the quality or length of protection the vaccines will provide and how effectively they will stop viral transmission. New variants of SARS-CoV-2 with mutations in key proteins threaten vaccine efficacy. Certain groups—eg, children, people with immunodeficiency, pregnant women, and elderly people—were not included, or were underrepresented, in vaccine trials, making the safety and efficacy in these groups less certain. Supply-chain constraints, pricing, and unequal vaccine procurement across countries mean that coverage across most, if not all, countries will remain below the level required for herd immunity—if such a level exists, another unknown. We can say that vaccines will make an important contribution to returning life to normal, but they should be only one part of an exit strategy.
Certain countries that have relied on a suppression strategy for pandemic control, using non-pharmaceutical interventions to reduce cases, hospital admissions, and deaths to so-called acceptable levels before lifting restrictions, appear to be entirely dependent on population-level herd immunity generated through natural infection or immunisation as an exit strategy. Public health messaging in these countries, which include most countries in Europe and the USA, is that we must both await the vaccines and become accustomed to living with the virus, as we have done with other viruses in the past. We should expect SARS-CoV-2 to become endemic and, potentially, seasonal. Infections will be concentrated in certain pockets of society that are non-immune, such as children who have not yet been vaccinated or adults with waning immunity. The virus might even become less virulent over time through accumulation of mutations and a selective pressure to become more transmissible as it adapts to humanity following the jump from the original animal host. However, even if these assumptions about the virus' trajectory hold true, they will happen over many months and years. In the meantime we must decide how best to ameliorate the detrimental effects of this deadly virus.
Another strategy in use—to eliminate—has been deployed by countries that have been arguably the most successful in their responses to the pandemic: New Zealand, Australia, Taiwan, South Korea, Vietnam, and China. This strategy, which is proactive rather than reactive, resembles an exit strategy to a far greater extent than does the suppression strategy. It has a clear goal: to reduce community transmission to near zero through a highly stringent, but short-term, lockdown, followed by implementation of a well sized, robust, and coordinated find, test, trace, isolate, and support system, with the aim to identify and end outbreaks before they become unmanageable. Key to the success of this strategy is removal of structural inequalities that might lead to resurgences of the virus in certain marginalised populations. Benefits of this strategy have been multitudinous, including far fewer COVID-19 cases and deaths and in the long-term mitigated impacts on the economy and wellbeing of societies.
Border closures and travel bans have been essential to limit reintroductions of the virus in countries pursuing an elimination strategy. However, borders cannot remain closed forever. A policy document from Germany paints a picture of how elimination across Europe might be sustainable, although the sentiments could be applied globally. The document proposes that areas in which SARS-CoV-2 has been eliminated are declared green zones in which civil liberties are restored. Strict contact and travel restrictions outside green zones remain, but the green zones expand as more and more regions achieve elimination. This strategy would require a global, coordinated response—so far absent from the pandemic—but if achieved would reap benefits. WHO is well positioned to lead such as response; however, to be successful, an elimination strategy will require individual governments to look beyond their own interests and commit to zero COVID.
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