How sewage could reveal the true scale of coronavirus outbreak?


During the first COVID-19 peak in the year 2020, one thing became evident – disaster preparedness in health institutions is really wanting. On a given day, hospitals are operating at their usual pace and capacity. Come the next day, the hospitals are overflowing with COVID-19 patients. 

Then do you ask yourself – how come the health authorities didn’t see this coming?  As it is expected, with the advancement in technology, at least there should be some system in place to detect such spread of a viral disease in the community before things get out of hand. 

The missing link must be wastewater. Experts have since proved that sewage can indeed reveal the true scale of the COVID-19 outbreak. Before discussing the dynamics of this system, it pays to understand why the outbreaks catch almost everyone unawares.

4 reasons why detection of coronavirus outbreak delays

1. There are still many unknowns

The SARS-CoV-2 virus is still fairly new. Even worse is when it started in China. The problem with a new disease like this is that you may be positive yet don’t know it. You may even show the symptoms but brush them off as just another cold. As such, you don’t take any precautions to avoid spreading the disease – such as social distancing and wearing a mask in public. In a matter of days, you realize you have infected dozens of people. 

2. Not everyone takes a test

Many countries have to face the fact that COVID-19 test kits are low in supply. Even if they wanted, it is impossible to test every person in a given area. As such, the confirmed cases may not be a true representation of the scale of the outbreak.

3. Asymptomatic people don’t see the need to get tested

A good number of people have coronavirus in their system but they show no symptoms – what we refer to as carriers. Such people don’t see the need to take the test. Without knowing whether they are positive or negative, they continue with life in the normal way and end up spreading the virus to scores of people they come into contact with.

4. Symptoms delay

It takes about 1 week from the time a person is infected with the virus to when symptoms start showing. And remember it can go up to 2 weeks for some people. Thus a COVID-19 outbreak can be present in the population without authorities knowing.

Sewage can give early warning signs of an outbreak

One way to address the issue of delayed detection of coronavirus outbreaks is through testing the presence of the SARS-CoV-2 virus in sewage. Most municipalities have toilet systems that connect to a central wastewater treatment plant. As a matter of fact, a single treatment plant may be representative of millions of people in the community. 

What needs to be done is first analyzing the average quantity of viral RNA that is passed out with the feces for a single patient. Next, the concentration of viral RNA in the sewage is determined through sampling and testing. Extrapolation is done to estimate the total viral RNA released by the entire population. This way, the number of people infected with coronavirus can be estimated.

Research has already shown that it takes only 3 days for the coronavirus to appear in human feces.  If wastewater surveillance is done on regular basis, it means that the health officials will know what proportion of the population is COVID-19 positive, way before symptoms start showing and people start seeking treatment at nearby health centers. 

Comparison of the concentration of the viral RNA for different hours, days, or weeks can clearly show whether the COVID-19 infections are increasing or declining, and at what rate. 

With such information, health authorities can prepare health facilities to accommodate as many patients as the analysis recommends – and thus they will not be overwhelmed. They can also use the information to impose total lockdowns on notorious hotspots before things get out of hand.  

Even when the rate of infection slows down and life returns to normal, routine surveillance of sewage should continue. The second or third coronavirus waves won’t catch health officials unawares.  

There is great potential in this system as it is not an entirely new concept. Sewage surveillance has previously been used to assess the status of viral diseases such as polio, measles, and norovirus. It is now upon governments and other relevant authorities to make good use of the wastewater surveillance method to timely map coronavirus outbreaks in order to do what is required to prevent loss of lives.