Could wastewater surveillance protect Indonesia from the next pandemic?

The COVID-19 pandemic affected people and the economy in unprecedented ways. Mobility restrictions and the resulting economic slowdown dramatically increased unemployment rates and dragged millions of households below the poverty line.

Hospitalisation and mortality due to COVID-19 were high – the World Health Organisation (WHO) estimates 14.9 million excess deaths globally from the pandemic in 2020 and 2021. Other health conditions were also neglected due to the overwhelmingly unmet need for health services during the peak of the pandemic and the restrictions imposed during the response.

Unfortunately, there will be other pandemics in the future, possibly in our lifetime. Mitigating the effects of future pandemics depends on having a strong health system that can detect infectious diseases early enough to implement a swift and informed response. One of the best ways to do this is by developing a monitoring system capable of detecting disease transmission at the community level.

One promising option is Wastewater-Based Epidemiology (WBE) surveillance, a system that detects disease causing pathogens by testing samples from local wastewater systems. These systems are already operating in the United States – but are they feasible in the context of developing countries like Indonesia?

How do Wastewater-Based Epidemiology (WBE) surveillance systems work?

Individuals infected with a virus or bacteria, both with and without symptoms, shed fragments of the pathogens in their faeces, which are then disposed into the wastewater system. WBE surveillance systems periodically collect samples from specific wastewater points – such as water manholes, swimming pools, soil in public areas and river points adjacent to large population areas.

By analysing the concentration of pathogens in wastewater, the system can provide valuable insights on the prevalence of local infections, even among asymptomatic individuals who have not been tested. This information can be crucial for informing decisions about infection prevention and control measures.

WBE has already proven effective. In fact, it has been used to eradicate polio since the 1930s by providing early information on the disease’s spread. However, interest in WBE has surged in the wake of the COVID-19 pandemic.

The Centers for Disease Control and Prevention (CDC) in the United States have strengthened the WBE system to monitor the ongoing changes in COVID-19 cases. Other countries, like Singapore and Australia, have also adopted WBE surveillance in addition to individual-based testing methods like Rapid Antigen Testing (RAT) and Polymerase Chain Reaction (PCR) testing, to conduct extensive surveillance.

Do Wastewater-Based Epidemiology (WBE) systems have potential in Indonesia?

During the peak of the COVID-19 pandemic in 2021, teams from Universitas Gadjah Mada and the University of Melbourne did a study in Yogyakarta Province. The study found a high prevalence of COVID-19 virus fragments in the community wastewater samples, ranging from 34-43%.

We extended the aforementioned study by including a modelling-based cost-benefit analysis to determine whether the additional costs of implementing the WBE surveillance system are economically feasible.

The modelling study showed that WBE surveillance could potentially reduce COVID-19 virus transmission, depending on how much testing capacity can be ramped up and geographically targeted. For example, the model estimated a 10% infection reduction by doubling the daily testing rate, from the very low average number of 55 tests per 10,000 people with COVID-19 symptoms in 2021. This level of infection reduction could be achieved assuming that early outbreak warnings from the WBE system are followed by quarantine and isolation policies.

Taking into account the cost of setting up WBE and increased testing and quarantine, the simulation suggested a value of about $4,500 to 5,500 per DALY (Disability Adjusted Life Year) averted. DALY is a composite measure of health burden due to morbidity (due to infections) and premature death. This number is well under the common threshold of interventions to be deemed cost-effective which is about three times of a country GDP per capita (or about $13,000 in 2021).

Indonesia must be ready for the next pandemic

Disease surveillance systems are not a magic bullet. They can only effectively control the spread of disease when combined with other proven public health policies, such as community engagement, contact tracing and mobility restrictions.

However, a reliable early warning system is an essential component of any strong health system. The Covid-19 pandemic is a stark reminder of the importance of early detection systems. In 2021, an independent panel established by the World Health Organisation found the COVID-19 pandemic could have been prevented if an emergency had been declared earlier. Their report also called for the establishment of independent disease surveillance systems with the power to publish their findings.

Considering the inherent limitations of Indonesia’s current early warning system – which relies on expensive individual-based surveillance – integrating community-based surveillance could help save lives and identify healthcare efficiencies.

Incorporating WBE into public health monitoring strategies would not only enhance Indonesia’s ability to detect and respond to threats from COVID-19,  it could also help detect and inform responses to other infectious disease threats. This can help build the resilience of Indonesia’s health system and ensure Indonesia is better prepared for global health challenges in the future.