How rainwater and sewage help fight a pandemic

One of the biggest challenges of the still ongoing pandemic is the rapid identification of mutated, unknown variants of COVID-19. As it turns out, sewage can be helpful in monitoring the spread of the virus! Or rather, the information that can be read from it.

Biological content monitoring

Monitoring wastewater for biological content has been a common practice for many years. However, the coronavirus pandemic has increased the importance of this type of activity. Detailed analyses of wastewater are increasingly being carried out to identify the viruses and pathogens present.

Indeed, microbiologists have discovered that sewage surveillance can be successfully used to detect the presence of coronavirus. This is a way of tracking the development of individual variants of the virus. This also makes it possible to identify completely new outbreaks and discover previously unknown strains.

Currently, in some countries, wastewater monitoring is one of the main sources of information on pandemic progress. Despite the complexity of the VOC analysis process, more and more entities are taking an active part in wastewater testing. This is not surprising. This is because it makes it possible to determine the dynamics of the virus and the effectiveness of the vaccination carried out in particular areas.

Wastewater – a valuable source of information for identification of mutations?

Two distinct approaches are used in the wastewater surveillance process:

• The first is based on procedures for sequencing the viral genome and searching for it in the analysed effluents.
• The second is based on polymerase chain reaction (PCR) by identifying the presence and amount of coronavirus RNA.

And it is this second method that allows the identification of mutations and their characteristics. Each mutation is assigned a unique code, which allows the information acquired to be organised. A few individual drops of contaminated water are usually enough to acquire variant data. At the same time, the methods used are incredibly effective. It is estimated that by analysing the obtained fragments of the genome, even small mutations can be identified (with a contribution to all infections of less than 1%).

Extending findings from tests

Analysis of biological fragments in wastewater provides data that were not possible to obtain with traditional coronavirus testing in patients.

An interesting experiment in this area was conducted in the Netherlands. Researchers compared around 1,000 clinical samples from patients with wastewater samples taken from the same locations.

Testing the contaminated water allowed for obtaining faster and more extensive data. Indeed, it turned out that the effluent sequences reveal mutations that were not recognised when clinical tests were performed. It is even speculated that these mutations may represent completely new, previously unknown variants of viruses – hence the lack of clear identification by traditional tests.

Such knowledge can be used successfully to prevent the spread of new mutations. Indeed, the data obtained from wastewater can provide an indication in the area of the direction of change and the potential risks involved. This is what happened in December 2020, when mutated variants were identified in wastewater. Just a few weeks later, it was these mutations that were seen in new variants of the virus.

Could the future be in wastewater?

Testing wastewater samples can determine the concentration of infected people in an area. Italian scientists even claim that the analysis of contaminated water can be an alternative to rapid screening tests. This is because it enables simultaneous analysis of data from a much larger number of people. And thus, the effectiveness of the carried out measures is higher.

Based on experience to date, Dutch Professor Medema recommends the development of technologies to monitor wastewater content. He sees a need to build a consortium including healthcare institutions, research institutes and water supply companies. Thanks to such cooperation, obtaining information on the course and development of virus transmission will be more efficient than ever.