The COVID-19 pandemic, which has affected us all for the last nearly two years, has without doubt led to fantastic scientific research and breakthroughs, forging the path for new therapeutics and scientific collaborations. But there is an unsung scientific hero of the pandemic that perhaps gets less media attention than it deserves — wastewater-based epidemiology and surveillance. It’s a mucky subject, but I’m going to keep this blog post clean and focus on the science.
As the virus is discharged from infected people through coughs and sneezes, it also sheds through our other bodily functions. Wastewater monitoring is not a new concept; this type of surveillance has typically been conducted for monitoring drugs of abuse, and if you look to the academic researchers, there are many studies on wastewater surveillance for illicit drugs, other viruses such as norovirus and adenovirus, pesticides, and pharmaceuticals such as antibiotics.
In March 2021, the European Commission recommended that each member state put in place a wastewater-based epidemiology surveillance program and share report findings. With the goal of spotting outbreaks and creating an “unprecedented alliance between the European water sector, the public health sector and the scientific community, with the Commission’s Joint Research Centre providing the necessary scientific know-how and infrastructure, and acting as an innovation uptake accelerator. This scientific push has enabled the Commission to take swift action in support of EU Member States’ continuing efforts to stop the spread of COVID-19.”
Ultimately more data, more knowledge, more action.
While the COVID-19 pandemic has been the driver for this initiative, once in place the programs can be adapted to track other viruses as well as provide key indicators of public health.
One publication on wastewater surveillance data from Barcelona, Spain, would have predicted the initial outbreak by several weeks and also the onset of the second wave. The data also showed the effectiveness of lockdown measures, and by monitoring certain sewers, they were able to spot an outbreak and perform targeted population testing. This is a key factor in controlling spread by asymptomatic people. You will find similar results from Italy, France, Germany, the Netherlands and more, so without doubt, wastewater-based epidemiology has its place as a highly efficient and cost-effective way to monitor outbreaks.
The UK, although no longer a member of the EU, also has adopted a similar framework for monitoring SARS-CoV-2 in wastewater. A new laboratory was set up under the UK government’s surveillance program, led by the Joint Biosecurity Centre (JBC), as part of NHS Test and Trace, in collaboration with Defra (Department for Environment, Food and Rural affairs), the Environment Agency and other partners. They also state that expansion of the program could be beneficial by providing information on other infectious diseases.
Quantifying SARS-CoV-2 genome by RT-qPCR is the way to detect the virus, but there are other measures that must be accounted for, including normalization, which considers water flow, wastewater contributions, population size, effluent discharges plus other factors — including tourism — which could affect concentrations.
While understanding viral load as a key indicator is paramount, what about the relationship with other wastewater biomarkers such as ammonia and orthophosphate, urea and pH?
Is there a relationship between outbreaks and changes in these measures? What other ways can we normalize the data?
This question is the next step in wastewater epidemiology: How can you derive the full picture from all wastewater data? Could you eventually pick up on a potential outbreak with simple biomarker indicators rather than full genome testing?