Covid-19: Strategic Options

It is of crucial importance for governments to make an assessment as early as possible in an epidemic as to whether to adopt a containment or a management strategy. The cost in lives and in economic terms of switching from management to containment is severe, as we are seeing in the case of Covid-19. We consider a containment strategy to be the optimal response to the current pandemic.

There are broadly two strategies that may be adopted in response to an epidemic or pandemic, such as Covid-19:
– Containment aims to prevent the transmission of the disease completely and reduce its incidence in the infected population, ideally to zero. This strategy can be summarised as “the Hammer and the Dance” [1]. The Hammer involves drastic measures, such as “lockdowns” to “break” epidemic outbreaks, Wuhan being the prototypical example. The Dance relies on the ability to test for infection at scale and to track and isolate cases and their contacts in order to prevent further outbreaks and contain any clusters that may develop. See the STOPCOVID.WORLD infographic [link to be added when the infographic is online] for more explanation of the containment strategy.
– Management aims to reduce the impact of an epidemic by control and mitigation measures. In this strategy any drastic action would be aimed merely at reducing the level of infection to manageable levels. Other steps that mignt be taken include sheltering vulnerable individuals, such as those with compromised immune systems, and, in the case of Covid-19, the elderly.

Of course, either strategy needs to be continued only until preventatives, such as vaccines, or effective cures, such as new or repurposed drugs with tolerable side-effects, become available, although it should be noted that by this time there will have been many more cases – possibly by orders of magnitude – where a management stategy has been followed than under containment.

The implementation of either strategy will almost certainly include elements of both, but the overall goal is critically important, because any drastic steps to achieve containment are best taken as early as is politically feasible in an epidemic, whereas, in a management strategy, drastic mitigation steps are best implemented when the epidemic is nearing its peak.

Factors influencing the choice of strategy include:
– The severity of the disease.
– The prospect of the identification and effective deployment of preventative or therapeutic treatments, such as vaccines or drugs.
– The ability to detect infection either by identifying symptoms (such as body temperature in the case of SARS) or by testing for the infectious agent or a physiological reaction to it which is possible for Covid-19, even when infected individuals are asymptomatic.
– The incubation period of the disease, especially the time before an individual becomes infectious. The longer this is, the more chance there is of detecting and isolating cases before they are able to transmit the disease.
– The choices made by neighbouring countries and trading partners. There is a network effect in that it would be extremely disadvantageous to be in a minority of countries following a management strategy in a containment world.

It should be noted that these criteria suggest the judgement would tend more towards containment than in the past, especially if we look back as far as the last global epidemic of comparable severity, the Spanish flu epidemic of 1918:
– With 21st century healthcare technology, early death from all causes is much less common, so the perceived severity of any epidemic is higher, for a given mortality rate.
– The development of vaccines and identification of new drug therapies is nowadays a realistic prospect within the timescale of an epidemic, especially if steps are taken to slow its progress. Containment measures are therefore likely to be needed only for a limited time.
– We are now able to develop tests for pathogens of any known type within weeks. Again, time is on our side: with greater testing capability and the development of tools for contact-tracing, less drastic containment measures (principally more targeted isolation, rather than of the whole population) become increasingly more practical.
– We live in an interconnected world with rapid travel. It would be difficult for one country to mitigate being “cut off”.

In addition, modern media and the internet allow immediate emotional engagement across the world. Our screens were full for weeks with images of suffering from Wuhan.

It should have come as no surprise to anyone that containment was necessary, yet apparently in many countries it did.

We observe that the consensus approach among epidemiologists is to attempt containment in the early stages of an epidemic and then, if necessary, switch to management. For example, in the H1N1 “swine flu” epidemic of 2009, containment quickly failed and the epidemic was managed, although it turned out to be less severe than it initially anticipated and few effective concrete management steps were taken. In contrast, containment measures have in recent years been effective for Ebola haemorrhagic fever and SARS, although if they had not been, the severity of both is such that we would have been forced into a containment strategy whatever the expense.

One problem with this approach is that it can create the illusion of a “fall-back plan” if containment “fails”. The discourse of epidemiologists tends to suggest this is the case:

Once the infectious disease threat reaches an epidemic or pandemic level, the goal of the response is to mitigate its impact and reduce its incidence, morbidity and mortality as well as disruptions to economic, political, and social systems.

[2], p.30 [our stress]

There is no mention of, for example, weighing the cost of more drastic containment measures against the impact of the epidemic. Because, logically, containment is always possible; it is just a matter of the cost.

It is absolutely crucial to make an early assessment of the strategic options, in particular whether a management strategy is acceptable. In this assessment, the bias should be towards containment, for three main reasons:
– The precautionary principle: the impact of a new disease is uncertain in the early stages of an epidemic.
– It is much cheaper to switch from containment to management once more facts are known, than, once a disease outbreak has grown in size, from management to containment.
– Containment buys time for the development of therapies and preventative treatments.

We believe Covid-19 is an example of an epidemic for which a management strategy is not an option ([3], [4]). The acceptability of an estimated 1% mortality rate – principally those with “pre-existing health conditions” – of the 50-80% of the population who would need to be infected with the virus to achieve “herd immunity”, may perhaps be a legitimate matter for moral debate. But it is clear that Covid-19 has the capability to overwhelm any health service in the world when only a low single-digit percentage of the population has the disease. There is very little dissent anywhere against measures to prevent this happening. “Overwhelm” would inter alia lead to an increase in the mortality rate, as many of those whom medical interventions could have saved instead succumb to the disease, and health services become less effective at treating other, unrelated conditions.

Because of the impact on health services and the psychological impact of that on the public, Covid-19 is even more severe than the mortality rate suggests.

A containment strategy is mandatory, at least in developed countries.

A failure to understand the risk of overwhelm and the mistaken belief there was a contingency plan – management – may have led to insufficient containment efforts early in the pandemic in many countries, such as the UK. Earlier quarantining of travellers (or travel bans from affected regions) and greater investment in contact-tracing might have been effective in slowing the transmission of the disease. Physical distancing and lockdown measures could have been taken much earlier.

We have thus already seen a number of countries, particularly in Europe, attempt to respond to Covid-19 with management strategies, but later switch to containment strategies. This was a catastrophic error because many countries’ epidemics have reached a stage where they are difficult and expensive to contain. Earlier action would have reduced the duration of containment measures and the number of fatalities (as well as morbidity requiring extreme medical interventions, the long-term consequences of which are currently uncertain, but almost certainly seriously adverse).

We note evidence of a collective failure of imagination amongst decision-makers (governments and their medical and scientific advisors), at least outside Asia. The pre-Covid-19 consensus position of the epidemiological community is perhaps summarised by the WHO (though it should be said WHO officials have been among the most vocal voices urging the global community not to give up on containment):

We have also seen that many traditional containment measures are no longer efficient. They should therefore be re-examined in the light of people’s expectations of more freedom, including freedom of movement. Measures such as quarantine, for example, once regarded as a matter of fact, would be unacceptable to many populations today.

[2], p.26.

We suspect that epidemiological textbooks will need to be revised once the Covid-19 pandemic has ended.

We end by briefly noting 3 cases:
– China realised early (but perhaps not early enough) the imperative of containing Covid-19 and enacted draconian quarantine measures, combined with a rapid ramp-up of testing and contact-tracing, which has succeeded in containing at least the first wave of the Covid-19 epidemic in that country. China had the “advantage” of the experience of a SARS epidemic in 2003, and presumably had pre-existing contingency plans for an new outbreak of SARS or something similar. Covid-19 falls into that category. China (population 1.4 billion) has to date reported 3,304 fatalities.
– The UK‘s initial containment measures “failed” and the country initially adopted a management strategy, based on pre-existing plans for a flu epidemic. This was a category error. There was a belated realisation ([4]) that “mitigation” measures to “flatten the curve” of the UK epidemic would still overwhelm the UK’s National Health Service (NHS) many times over, and “suppression” measures are currently being adopted. The UK (population 68 million) currently expects around 20,000 fatalities, a mortality rate about 120 times that in China.
– New Zealand adopted strict nationwide “Level 4” containment measures soon after it became clear that local transmission of Covid-19 was occurring, and before any deaths had occurred.

We recommend the strategy followed by China to control existing outbreaks and by New Zealand for those territories yet to experience outbreaks. There are many other lessons to be learnt from other countries, particularly those in Asia, especially in the use of testing, contact-tracing and isolation to contain Covid-19.

Note on style
Some readers may be disappointed that this post is not written in the usual flippant style of Uncharted Territory. The reason is that it has been written as proposed content for the site STOPCOVID.WORLD (under construction at the time of writing).

Note on terminology
We follow the terminology in general use for measures to respond to epidemics and pandemics, such as “containment”, “control”, “mitigation”, “elimination”, “eradication” (see for example, [2], p.30), “breaking” epidemic outbreaks and “suppression” ([5]).

However, we find an insufficiently clear distinction in the literature between alternative strategies governments and, in the case of pandemics such as Covid-19, the global community may choose to adopt. We therefore use “containment” in a broader sense for a strategy purely focussed on preventing the spread of an infectious disease and “management” for one based entirely on control and mitigation measures to minimise the impact of an epidemic.

References
[1] Tomas Pueyo, Coronavirus: The Hammer and the Dance, accessed 1st April 2020.
[2] WHO, Managing epidemics (pdf), version 1, 2018.
[3] https://johnmccone.com/2020/03/16/containment-or-bust/
[4] https://timjoslin.org/index.php/2020/03/15/the-covid-19-files-3-tims-plan/
[5] Imperial College COVID-19 Response Team, Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand (pdf), 16th March 2020.

Modification history
30/3/20: Initial version.
31/3-1/4/20: added explanation of containment and management strategies; other minor changes.