30 Mar 2020
Although scientists around the world are working at breakneck speed to research Covid-19, much remains unknown about the disease. Meanwhile, the number of cases and the death toll continue to rise rapidly. How do policymakers make public health decisions to effectively tackle a disease when information about it is limited?
Epidemiological modelling studies are increasingly gaining influence in guiding government response to rapidly evolving infectious disease outbreaks. Models allow public health decision-makers to take decisive action even when empirical data are scarce. Infectious disease modelling has been used to support public health decision-making in several major outbreaks such as H1N1 influenza in 2009, Ebola in 2014-2016 and Middle East Respiratory Syndrome (MERS) in 2015.
In the case of Covid-19, arguably no modelling study has been more influential than the one published by a team at the Imperial College London. The study modelled the potential impact of different strategies on Covid-19 outcomes for Britain and the United States. It suggested that even with intensive suppression strategies (measures short of a complete lockdown) Covid-19 will likely still cause high numbers of death and overwhelm Britain’s health system. One week after the release of the Imperial College report, the British government announced a strict lockdown after initially resisting such measures. In the United States, the Imperial College report has also influenced the White House to finally strengthen its response to Covid-19.
One of the major challenges that epidemiologists face in building their models is inadequate data. This forces infectious disease modellers to make assumptions that may be flawed. For example, existing models do not capture the development of biomedical interventions such as faster, easier tests to identify and isolate infections or an effective antiviral. Imperial College’s model, for example, did not consider the impact that rapid mass testing and contact tracing could have on reducing the number of new infections because at the time the model was being constructed, Britain did not yet have the capacity to do so.
Another limitation of these models is that they typically do not consider the economic implications of the public health interventions they recommend. The Imperial College’s report acknowledges this limitation.
Yet we cannot ignore the very real economic cost of measures such as the Movement Control Order (MCO) imposed in Malaysia, especially on segments of the population that are already underserved. The decision to extend the MCO until April 14 has been estimated to potentially result in 2.4 million people losing their jobs, with 67% of them being “unskilled workers”. Urban poor families living in PPRs (people’s housing projects) are likely to face further financial strain, as they are disproportionately more likely to lose their source of income and lose access to cheap food and goods through informal markets such as pasar malam (night markets) and pasar tani (agricultural markets) on which they are highly dependent. While existing government initiatives may help, they will likely not be enough.
This is not to suggest that economic considerations should triumph over public health issues; this is likely a false dichotomy. As ever, there is a need for scientists, public health experts, economists, academics and policymakers to work together to find solutions to resolve the current public health crisis in a way that minimises the potential economic impact.
Mass testing could be one of the most cost-effective public health interventions that governments could implement. Indeed, as noted by the director-general of the WHO, Tedros Adhanom, “Asking people to stay at home and shutting down population movement is buying time and reducing the pressure on health systems. But on their own, these measures will not extinguish epidemics…. Aggressive measures to find, isolate, test, treat and trace are not only the best and fastest way out of extreme social and economic restrictions, they’re also the best way to prevent them.”
Mass testing allows for early detection of infection in individuals so that these individuals can be isolated before they spread the infection to others. This strategy was crucial to South Korea’s containment of an outbreak of MERS in 2015. With Covid-19, South Korea again employed aggressive mass testing efforts followed with contact tracing and isolation, and so far has been one of a handful of countries to see a decline in the number of new infections.
Malaysia began preparing its own test kits against the Covid-19 virus as early as Jan 3 in anticipation of the outbreak reaching and spreading in Malaysia. By March 28, we had carried out 35,516 tests, approximately 1,000 tests per million inhabitants. This is a significant increase in a matter of days; on March 25, Malaysia had carried out just under 21,000 tests, or about 640 tests per million inhabitants. Health Ministry director-general Datuk Seri Dr Noor Hisham Abdullah has announced that by the first week of April, Malaysia will be able to increase its testing capacity to 16,500 tests a day.
For now, Malaysia is almost exclusively using test kits that detect the presence of the Covid-19 virus by using a technique called reverse transcription polymerase chain reaction (RT-PCR). These test kits are reliable but they typically take a few hours or up to a day to produce results and depend on laboratory equipment. Another type of test is available that detects the presence of antibodies that are produced by the immune system in response to the presence of viruses. These tests can produce results within minutes and can be done almost anywhere; however, antibodies are only produced after a few days of being infected by the virus. For this reason, the Health Ministry has chosen to not use these test kits for diagnosis.
However, these antibody-detection tests could serve a useful purpose for infectious disease researchers. At the moment, it is unknown how many of the population have actually acquired the Covid-19 infection. This is because there may be large segments of the population that are infected but have gone undetected because they are asymptomatic (not showing symptoms) or only have mild symptoms.
Unlike the RT-PCR tests that detect ongoing infections, antibody-based tests can tell who amongst us have been infected, with or without symptoms. Large-scale antibody detection testing would allow epidemiologists to understand actual infection rates and actual mortality rates so they can present a more accurate projection of the potential outcomes of Covid-19 and the effectiveness of different public health strategies.
Additionally, these tests could also potentially help identify those who have developed an immunity to the Covid-19 virus, who can then return to normal life, re-entering the workforce and jump-starting the economy, knowing they can no longer infect others.
In this war against Covid-19, the virus is the enemy, albeit an “invisible enemy” – but it does not have to be, as mass testing would let us know exactly where the virus is hiding. This would allow policymakers to devise strategies to catch the infections early enough so we can isolate and treat them before they spread to others and overwhelm our healthcare system, while minimising the social and economic fallout. If this pandemic is war, mass testing is one of the best weapons in our arsenal, and we would do well to invest more resources in deploying this strategy.
NAZIHAH MUHAMAD NOOR
The writer is a research associate at Khazanah Research Institute who holds an MA in Public Health and a BSc in Biomedical Science (Global Health)