Need for strong outbreak prevention measures that are appropriate and timely

In recent days, there has been an exponential rise in confirmed COVID-19 cases. The numbers may appear staggering, almost a doubling of cases in one day; however, the worse may yet be on the horizon. We seem to still be in the early stages of this global pandemic. Outbreak cases increase on a multiplicative scale. Assuming a reproductive ratio (RR) of 2, on average 2 cases infects 4 who then infects 16 who then infects 64; with each transmission cycle taking on average 7-21 days. The increase in cases is gradual initially, but once there is an uptick, the increase in numbers can become daunting. The initial stage of an outbreak is known as the containment stage and then naturally progresses to a mitigation stage with community transmission of the disease. A viral epidemic usually dies out as more and more people get infected, recover, and are then immune to the disease (Herd Immunity).

The most effective preventive measures are those aimed at preventing the general public from getting infected. These Public Health measures include isolation, quarantine, and social distancing. Lockdown is an extreme approach for implementing one of these measures. All these measures aim to break the chain of disease transmission. These terms should not be used interchangeably because they each have different aims and benefits.

Isolation removes an infected individual from the population. Isolation aims to reduce the chance of susceptible public getting exposed to cases. In the initial containment stages of an outbreak, these cases may be isolated in the hospitals. In the later mitigation stages of an outbreak, there may be a need to triage hospital admission based on the severity of COVID-19 rather than just the presence of disease. Those with mild disease should then self-isolate themselves.

Quarantine removes susceptible individuals who have been exposed to the disease and do not display any symptoms for 14 days from last exposure. For a quarantine to be useful, the people who may be incubating the disease must be effectively and efficiently identified and the person being quarantined has to comply with the order. Quarantined individuals are served orders by the Ministry of Health to stay away from the public. Public health officers then conduct home surveillance of these individuals for the period of the quarantine.

Isolation and quarantine are critical preventive measures during the containment phase of an outbreak. As an outbreak evolves, there will be new cases with no previous (epidemiological) link to prior cases, and third and subsequent generations of disease transmission occur. This community transmission of COVID-19 leads to the need for a broader community mitigation strategy. Social distancing is one such example. It is different from isolation and quarantine as it emphasizes a collective responsibility and empowers the public to reduce COVID-19 transmission.

Social distancing reduces COVID-19 transmission by increasing the physical distance between people and the frequency of group gatherings. The aim is to reduce the likelihood of the public encountering a case. The following measures may be utilised for social distancing:

1. encouraging workers to work from home;
2. reducing extracurricular activities and school assemblies;
3. temporary closure of schools;
4. temporarily migrating our education delivery system online;
5. discourage/ban large gatherings;
6. Encouraging take-aways and utilization of online food deliveries.

The suitability of the chosen social distancing measure depends on whether there are minimal, moderate, or substantial levels of community transmission.

A lockdown is a more extreme measure to prevent disease transmission. It is characterized by enforced curfews with the public only being allowed to leave their homes to buy groceries, seeking healthcare, for an emergency, or permitted work. The declaration of a Public Health Emergency or Disaster is different from that of a lockdown. The primary aim of an emergency or disaster declaration is to mobilize and distribute resources to where it is needed most.

Deciding on an appropriate preventive strategy is essential. The decision must balance the level of community transmission and impact of COVID-19 with the holistic cost of the prevention strategy. A lockdown, for example, appears on the surface to be the most effective preventive measure to reduce disease transmission. However, a lack of public buy-in and compliance will lead to it being ineffective in reducing disease transmission. Besides, there is a lot of direct and indirect negative cost associated with a lockdown. In an unprepared community, a lockdown may result in loss of economic output, increased psychological distress, and breakdown of social structures.

The numbers of COVID-19 cases is only going to rise. Many of us may get COVID-19, and a few of us (<15%) will have more severe symptoms that may require hospitalization. The public needs to accept that. There is a need for strong outbreak prevention measures, but the measures we choose should be appropriate and timely to ensure a healthy Rakyat. As an outbreak evolves, so does the appropriateness of a preventive measure.

Written by Dr Sanjay Rampal is a Public Health Medicine Specialist and Professor of Epidemiology at the Dept of Social and Preventive Medicine, University of Malaya. He is also Chair of the Public Health Society Malaysian Medical Association.