The World Health Organization declared COVID-19 a pandemic in March 2020. A year after the declaration, researchers, scientists, and innovators are still struggling to find effective ways to detect, contain, and treat COVID-19 outbreaks. The public health directives recommended preventive measures like social distancing, washing hands with soap frequently, and self-isolation for those who get exposed to the virus. Many countries are still requesting people to stay home and avoid trips outside their homes unless absolutely necessary.
Multiple pharmaceutical companies have announced success with creating vaccines. However, questions around the conditions for safe transport, costs, and effectiveness of these vaccines might delay the accessibility of vaccines to people around the world. The effectiveness of drugs against COVID-19 remains questionable. Antivirals such as Remdesivir made headlines when they were found to reduce the severity of COVID-19. Drugs for treatment have to be tested and approved before they are recommended for safe use. Often, they pose the same challenge as vaccines, restricting their availability to the public. So, in the future, buying over-the-counter medications for COVID-19 might become as common as buying personal care products. This may make COVID-19 common like the flu, but at present, the health fraternity has to concentrate its efforts on better prediction, containment, and control of outbreaks.
Scientists are studying the possibility of using COVID-19 detection from wastewater as an effective method to predict and prevent outbreaks in communities. To do this, wastewater is collected from wastewater treatment plants regularly and analyzed to find the number of COVID-19 viruses present in it. Companies that provide waste management services help in collecting and transporting wastewater safely to laboratories. The wastewater is sifted and processed prior to beginning the laboratory tests that identify COVID-19 ribonucleic acid (RNA) in the samples using polymerase chain reaction (PCR). Results from these wastewater treatment lab tests are then used to track the trends in COVID-19 activity in a community.
Reasons to Use This Method
Studies show that many people with COVID-19 shed viruses in their stools even before they begin showing any other symptoms. As people use the bathroom every day, these viruses are collected into the sewage treatment plants daily. The virus could also be collected from hands and bodies washed in sinks and showers. Therefore, wastewater treatment lab tests can be used to predict outbreaks by keeping an eye on the changes in viral levels in wastewater daily.
Looking at the number of people who tested positive in a day is another indicator that can be used to predict and control community spread. However, testing is an individual’s choice. People with mild or no symptoms might not get tested at all or prefer avoiding testing. Individual testing takes time as results can take a few days to process depending on how busy the testing center is. Therefore, the number of people who test positive daily only gives us the opportunity to look back at an active infection spreading in the community.
Collecting wastewater from sewage treatment plants daily is less intrusive and can be done daily without knocking on individual doors to collect samples. After wastewater treatment lab tests, the results are charted daily to find out communities where the virus is spreading rapidly. These tests can detect an uptick in COVID-19 infections up to one week before corresponding numbers show up in community testing. Therefore, wastewater treatment lab tests can be used as an early indicator of an increase in the number of COVID-19 infections in a region.
A rapid increase in severe Coronavirus infections can adversely affect the ability of hospitals to provide quality medical care to patients. Using wastewater treatment lab tests to predict outbreaks can help slow down and stop the spread in a community.
A Method Proven Over Time
In 1854, John Snow conducted experiments in England, where he tested water in areas affected by the cholera epidemic. His detailed investigations proved that contaminated water caused and continued spreading cholera in the community. He studied the epidemic in Soho district of London, and he found that contaminated water from the Broad Street pump was the cause of the epidemic. When the water handle was removed, new cases of cholera stopped in the district. In another instance, he studied water from water supply systems that drew water from two separate areas of the river, one of which was contaminated with sewage water. He proved that areas that received water from the contaminated portion of the river had a far bigger number of cholera infected people than those using the uncontaminated water source. His studies helped revolutionize residential and commercial plumbing and sanitation. As a result, in the next few decades, sewage drainage systems and water purification systems were built to prevent water-borne diseases.
In more recent times, researchers conducted a study in Sweden in 2013, where they investigated the presence of eight viruses in sewage water. The results from the wastewater treatment lab tests found a direct relation between the presence of viruses causing gastroenteritis in the collected wastewater and the number of reported infections. Noroviruses were detected in the sewage samples two to three weeks before patients were diagnosed with an infection. Over the years, study of pathogens in wastewater has been proven as an effective tool to detect infectious outbreaks early.
Variants in Wastewater
Viruses undergo mutations over time. Some of these variants become more prevalent than others in a region. Recently, COVID-19 variants of concern have emerged from UK, Brazil, and South Africa. These variants spread faster and quicker among people and can cause more severe illness. The effectiveness of vaccines against these variants is yet to be studied. So, even after receiving a vaccine shot, preventive measures will have to be maintained. Wastewater treatment lab tests can detect these variants of concern and this data can be used to make people aware of the increased risk.
For example, a recent study in the city of Houston found the UK variant of COVID-19 in most of its wastewater management plants. They also noticed that the variant was now found in more wastewater management plants in the past weeks. This indicates that the variant has been spreading rapidly in the city. At a time when the city is considering easing preventive mandates, this trend is alarming. Therefore, the city must continue to encourage its residents to continue wearing masks and keep up social distancing to slow down the spread of these variants.
Community Measures to Prevent Spread
Wastewater treatment lab tests have been proven to be a good indicator of the spread of COVID-19 in the community. The available data can be used to predict outbreaks. Data from studies have shown that wastewater samples show increased viruses at least one week prior to increased numbers in reported COVID-19 cases. As these results are an early indicator of possible community spread, this data can be used to predict outbreaks. Armed with this data, public health systems can use more targeted preventive measures to stop spread, such as running awareness campaigns in affected communities, offering door-to-door testing kits, encouraging testing, and asking affected people to self-isolate. With a head start in predictive data and estimated trends in the spread of infections, public health systems can work on replenishing dwindling health care equipment supplies like ventilators and personal protective equipment in areas that have the possibility of an outbreak.
Studies in England conducted using wastewater treatment lab tests indicate that COVID-19 was spreading in schools when data available through PCR tests indicated a downward trend in infections. This study took samples from the waste pipes of participating schools every five minutes for eight hours in a day. The data collected showed that while the wastewater treatment lab tests showed increasing numbers, the numbers from reported positive cases in the community caught up within a week. This information can be used to ramp up testing efforts in schools and providing child health care and support where required. However, it cannot be a good measure to use while making the decision to close a school. Data from wastewater treatment lab tests can only predict outbreaks since they analyze a sample from a vast pool of individuals. Testing wastewater cannot identify individuals or households with an active COVID-19 case. Hence, other methods like increased testing should be used to find exactly how many people are affected. More studies like contact tracing must be done to find out where and how COVID-19 infections are spreading.
In communities that have a high population density, outbreaks can be disastrous. In communities with high rise buildings and condominiums, wastewater treatment lab tests can help to warn residents and ramp up efforts to clean commonly used surfaces. COVID-19 can survive on surfaces for long periods when the conditions are favorable. So, if the possibility of an outbreak is detected, vigorous and regular cleaning of elevators, lobbies, and common areas must be encouraged in buildings.
Effectiveness of This Method
The use of wastewater treatment lab tests is better and more cost-effective than relying on nasal swab tests. The number of positive COVID-19 cases indicates how many people from those who opted to get a test, are positive. It is not a true indicator of the number of people who are infected by COVID-19. As these studies take samples daily and compare the number of viruses in the samples every day, the data from the study can be used to reliably determine whether a COVID-19 outbreak is occurring in a community.
Wastewater treatment lab tests can find COVID-19 viruses in a sample when one person in 10,000 people are affected. A few factors are known to yield variable results in the wastewater readings. These include the low levels of virus in stools, low number of infected individuals as compared to the total population, and breakdown of RNA materials in harsh wastewater conditions that may lead to lower readings. The strong correlation between the data emerging from wastewater treatment lab tests and data from other well-known measures to detect COVID-19.
In Australia, sewage is routinely tested to find the presence of COVID-19. Communities, where wastewater samples are found to have COVID-19 RNA, are placed on high-alert and people are encouraged to get tested. Areas that have active COVID-19 cases are mandated to restrict travel. Australia’s water research and sanitation group works together with researchers to detect and inform residents about the presence of COVID-19 viruses in the wastewater collected from their community. Over time, they developed skills and resources to regularly collect wastewater samples efficiently. Then they used wastewater treatment lab tests and analyzed the data. This was used as an early warning system to determine immediate measures required to control and curb outbreaks.
Depending on the severity of the data available, rules were amended. For example, if the tests found an unusually large number of viruses in a community, policies would be formed to restrict large gatherings and restrict travel to and from the affected areas. Innovative methods and technology are used for sample collection, data analysis and communication of the test results with residents in the communities where sewage water is tested for COVID-19. The pandemic has forced entire countries to lock down and shutter businesses for large periods of time. In these times, Australia has used creative methods like using predictive data to narrow down regions that can see an increase in infections and then closing down only those areas while other regions remain open for business. This has allowed to soften the blow that the pandemic has dealt small businesses. Australia’s pandemic response and infection control measures have won appreciation all over the world. As a result of their efforts, COVID-19 infections are absent in most provinces and the COVID-19 positive numbers in affected provinces are extremely low. Testing wastewater for the presence of COVID-19 has proven to be an effective method to predict COVID-19 community outbreaks all over the world, with fantastic infection control results in Australia. In the near future, wastewater testing to detect unknown infectious pathogens is expected to gain popularity and grab the attention of researchers worldwide.