By Dr Auni Aslah bin Mat Daud

The government implemented a four-week Conditional Movement Control Order (CMCO) on all states in Peninsular Malaysia except Pahang, Perlis, and Kelantan from Nov 9 to Dec 6 due to the recent spike in the number of COVID-19 cases.

Regardless of what measures the government will implement in the fight against COVID-19, their success will largely depend on the cooperation of Malaysians, who are now into the ninth month of the MCO at various levels.

However, maintaining Standard Operating Procedures (SOPs), such as mask-wearing, hand washing and physical distancing on a timescale of months or even years, would require a great sacrifice and a very high level of compliance from the public.

Flattening-the-curve

It has been claimed that the third wave of COVID-19 cases in Malaysia is due to the public’s failure to adhere to the SOPs. While some experts attribute it to pandemic fatigue, this article discusses another possible factor - the mathematical misconceptions about flattening-the-curve (FTC).

You may have seen the FTC graph on social media or news outlets. It consists of a tall, narrow curve and a short, wide curve. The curve being flattened represents the projected number of cases over time. There is a line through the graph that shows the number of patients the healthcare system can treat. The tall curve goes above the line, which means there are too many patients at one time that the hospital beds or ventilators may not be enough for all the patients who need treatment. The flattened curve shows what happens if the spread of the virus slows down.

The roots of FTC trace back to a paper published in 2007 by the Centers for Disease Control and Prevention in the United States, which was a preview to a pandemic like COVID-19.

Today, the term has become a rallying cry in the fight against the COVID-19 pandemic, popularised by journalists and government leaders worldwide. FTC is a useful and succinct way of conveying the importance of intervention measures and SOPs to the public in taking the burden off the healthcare system. This will buy us time to devise more efficient and sustainable initiatives, enhance the capability of the healthcare system and, possibly, develop a vaccine.

First misconception

The first misconception is the notion that using the FTC approach, the same number of people may get infected, but will lengthen the duration of the pandemic.

However, using a susceptible-infected-recovered (SIR) model, a recent study shows that effective implementation of intervention measures can reduce the number of susceptible individuals and the peak number of cases, and eventually shorten the duration of the pandemic.

Therefore, we can decrease the number of COVID-19 cases and fatalities with public health measures, without prolonging the lockdown and other extreme measures, which comes with great social and economic repercussions.

Moreover, there are at least three other independent studies, which also found that FTC will eventually decrease the total number of infections, namely by Prof Michael Höhle, (Stockholm University, Sweden), Prof Ben Bolker and Prof Jonathan Dushoff (McMaster University, Canada) and Timothy Churches (Senior Research Fellow at the UNSW Medicine South Western Sydney Clinical School). These findings emphasise that the physical distancing and other measures in FTC are even more important than expected.

Mathematically speaking, the public health interventions do not just flatten the curve, they shrink it.

Second misconception

The second misconception is due to a typically missing part of the often-cited FTC graph; what will happen after the curve is flattened?

As many countries are loosening lockdowns and other measures, the public can be misled into thinking that the COVID-19 pandemic is ending, and our normal life will return once the graph is successfully flattened.

However, many studies have shown that even if the measures are successful in flattening the curve initially, the number of cases will oscillate like a sine wave. That is, viruses often come back after they subside. In other words, the duration of intervention measures may not be important, if the transmission rate return to normal when the measures are loosened and the mortality rate remains the same.

Easing the control measures, and in the absence of other interventions, the number of cases will increase exponentially again, unless a large majority of the population has developed immunity (either from recovered infection or an effective vaccine) or the infectious agent has been eliminated, without any possibility of reemergence.

This might explain the resurgence of COVID-19 cases in Malaysia for the past few weeks. As a solution, some researchers from Harvard University suggest intermittent physical distancing measures through 2022 to prevent the healthcare system from being overwhelmed.

To sum up, while an effective, targeted CMCO may contain the outbreak, a correct understanding of FTC will help to find the optimal duration and frequency of its implementation, to achieve a perfect balance between health, economy, and social wellbeing.

-- BERNAMA

Dr Auni Aslah bin Mat Daud is Senior Lecturer at Universiti Malaysia Terengganu and Fellow of the Institute of Mathematics and its Applications (FIMA), United Kingdom.