COVID-19: What the evidence so far means for containment

Evidence always plays a major role in devising a strategy for any global health crisis – it becomes even more important when the circumstances of that crisis continuously evolve. With the total count of Coronavirus patients exceeding 885,000 across more than 170 countries, it is clear that COVID-19 is a once-in-a-lifetime pandemic and a crisis of unprecedented magnitude.

Italy and Spain now have over 100,000 confirmed cases of the virus, while the US will soon pass the 200,000 mark. The lesson from these developments is clear: we must abandon the assumptions that COVID-19 will be contained without drastic public health interventions.

On 16 March, researchers from Imperial College of London announced a searing report on the impact of an uncontrolled pandemic, that describes the cost of inaction: approximately 510,000 deaths in the UK and 2.2 million in the US. The report highlighted that infections would peak by the middle of June and, without effective policies in place, could lead to as many as 55,000 deaths on the worst day. This scenario is corroborated by emerging evidence suggesting that younger adults, who were previously thought to be less affected – are also prone to developing severe forms of the coronavirus infection.

Upon publication of the report, the UK government changed its previous policy of “building herd immunity” and the US reinforced its approach to adopt stricter measures towards containing the spread of the infection.

While the numbers in the report are sobering, it does provide guidance on how to develop a global health strategy for containing COVID-19. To be successful, all major countries around the world must act now.

The report described two major approaches available for containing COVID-19. One is mitigation: slowing down the spread of the epidemic but not interrupting the transmission completely, while ensuring the healthcare needs for those who are at risk of developing serious forms of the infection are met. This approach, which includes “social distancing” along with isolation and quarantining of cases, is unlikely to contain the pandemic and may result in the death of thousands of patients while severely burdening health systems, especially available intensive care units.

As such, the researchers recommend the second approach, suppression, as more optimal. Suppression refers to a reversal of epidemic spread by reducing the infectivity of the coronavirus and continued maintenance of this approach for up to 18 months. A reversal of spread can be achieved by the implementation of non-pharmaceutical interventions (NPI). These include strict lockdown measures – social distancing in entire populations, the closure of schools and community spaces – and extending these measures until vaccines can be developed.

Infectivity of COVID-19 is determined by its reproduction number, or R0 (pronounced R naught), which current epidemiological estimates suggest lies between 1.5 to 3. This means that every COVID-19 patient can infect up to three other people on average. The suppression strategy will require the elimination of human-to-human transmission by lowering the R0 to less than one, which is postulated to halt the spread of the infection. Mitigation strategies, the researchers observe, are unlikely to reduce R0 to less than one.

To achieve these metrics, the first step would be to test as many individuals as possible even the ones who may not exhibit symptoms. This is important because coronavirus infection has a longer incubation period of 1-14 days (compared to 1-4 days in flu) and emerging evidence suggests that people with mild or no symptoms may be responsible for the rapid spread of the infection.

This approach was also underscored by the Director-General of the World Health Organization), Dr Tedros Ghebreyesus, who highlighted the importance of “breaking the chains of transmission”. This identification of infected individuals by rapid and reliable testing will be crucial to building an effective approach to impede the spread of the infection.

The next critical step will be case isolation and voluntary home quarantines. These NPIs should be supplemented by strict social distancing with people maintaining almost six feet of distance along with the closure of schools, universities, bars, and other areas of social gatherings. This is especially important because recent investigation suggests that coronavirus is viable in aerosols for hours and on surfaces for days. The suppression strategy will also ensure that healthcare systems are not overburdened and capacity for critical care is preserved – a practice that has come to be known as “flattening the curve”. Failure to suppress the transmission of infection in countries like Italy has been responsible for the decimation of its healthcare systems leading to thousands of deaths.

The implementation of these suppression strategies is also the reason that countries in Asia, such as Singapore, Hong Kong SAR and Taiwan, China, have succeeded in maintaining low case counts of COVID-19. Learning from the experiences of the Severe Acute Respiratory Syndrome (SARS) epidemic of 2003 and swine flu of 2009, these countries instituted strict travel controls and rapid screening and contact tracing of infected individuals. To develop resilient response systems that can halt the transmission, these countries also escalated the production of tests for COVID-19 soon after the genetic sequence of the virus became available. Singapore even enacted mandatory quarantines with criminal penalties for violators. Although some experts have highlighted the limited applicability of complete lockdown measures in developing economies, such countries can still benefit from implementing strict mitigation strategies.

With a case fatality rate of up to 3.4% and up to 60% of the global population at risk, many of these measures may seem drastic, but they are also necessary to halt the transmission of this deadly pathogen. It may even seem an overreaction to an epidemic that is not well understood and where comprehensive data is missing. However, given the trajectory of the infection in Italy and the rapid collapse of its entire health system, it is prudent to exercise extreme caution to prevent other countries from trailing that path.

In moments of extreme uncertainty, the judgement of leaders is as important as evidence. To combat the pandemic of COVID-19, we will need to sacrifice short-term comforts for long-term gains. More than evidence, this will require courage on the part of national leaders; their next step will become a part of their legacy.

Disclaimer: The opinions expressed in this article are solely my own and do not reflect the views and opinions of Brigham and Women’s Hospital.