The positivity rate of SARS-CoV-2 from the wastewater samples collected in Bengaluru city between 11 and 22 December was around 96 percent.
Some areas near Sarakki STP in South Bengaluru, the SARS-CoV-2 viral load is more than 30,000 copies per ml. (TIGS)
As the Covid-19 cases are increasing across the country, Bengaluru is witnessing a wave-like situation as noted by wastewater surveillance.
The positivity rate of SARS-CoV-2 from the samples collected from the wastewater in Bengaluru city between 11 and 22 December was around 96 percent. These samples were collected across 26 sewage treatment plants (STP).
Wastewater surveillance of viruses has been done by the Tata Institute of Genetics and Society (TIGS), Bengaluru, in collaboration with the BBMP.
The surveillance shows the viral load of SARS-CoV-2 — Covid-19 — in the wastewater that comes from the households of the community. For more information about how it works, read here.
Between 10 December and 15 December, the SARS-CoV-2 copies per ml were 2,000, now it has increased to more than 3,000 copies per ml. In some areas near Sarakki STP in South Bengaluru, the SARS-CoV-2 viral load is more than 30,000 copies per ml, TIGS reported.
Realtime SARSCoV2 viral load in sewershed sites wastewaters and reported COVID-19 cases – the viral load shows an increase.
There is no clinical testing data available since 8th Nov. pic.twitter.com/gzdEw5rdHH
— Tata Institute for Genetics and Society, India (@TIGS_India) December 23, 2023
“This indicates a rise in the viral load within wastewater, signifying an increasing number of individuals shedding the virus. The current substantial data reveals a persistent upward trend, dispelling any initial concerns of a false alarm,” Dr Rakesh Mishra, Director of TIGS, tells South First.
He adds that the trend remains consistent, approximately 1.5 times the previous pattern, indicating a continued increase in the number of people shedding the virus. This phenomenon is observed not only in Bengaluru but also in other locations, such as Hyderabad, and potentially across the country due to extensive travel via air and train, creating a rapid homogeneity.
According to Dr Mishra, the ongoing surge in cases suggests that a considerable number of people are actively shedding the virus.
“Whether or not individuals undergo testing, many are asymptomatic carriers, unaware of their infection status. The fact that not everyone falling ill reports their symptoms underscores the prevalence of asymptomatic cases,” he points out.
He adds that this situation parallels the pattern observed after the Omicron variant emerged in January and, later, a subsequent hidden peak that went untested but was detected through wastewater analysis.
Further, he adds that the current surge is likely attributed to the JN.1 variant, known for its heightened infectivity and ability to evade the immune system, making it more efficient in transmission.
“The interconnectedness of regions implies that what is happening in one area, like Bengaluru, is likely to unfold in other parts of the country sooner or later, given the high level of connectivity. This rapid spread is a key characteristic of Covid-19, making it one of the most infectious viruses,” says Dr Mishra.
Dr Mishra says that the actual number of reported cases is significantly lower than the true prevalence, as testing is often only conducted only when there is a specific reason.
“The emergence of the peak began around 3-4 weeks ago, with a gradual increase initially difficult to discern. The initial blip prompted caution, necessitating further observation to confirm whether the trend was upward or downward,” he says.
He further adds that last week served as an alarm, “Today’s updated plot reinforces the escalating trend, providing a clearer indication of the emerging peak,” says Dr Mishra.
“Many places have curtailed testing after fewer cases, but surveillance continues, maintaining vigilance during seemingly uneventful periods. Despite a prolonged baseline phase that might seem uneventful, ongoing surveillance is crucial because the virus persists, not eradicated entirely,” he adds.
This sustained monitoring strategy allows for the identification of peaks, like the current one, which is expected to extend for the next two to three weeks before a potential decline.
Dr Mishra says that the absence of noticeable symptoms underscores the importance of advising people to wear masks and avoid crowds, yet there is no need for panic or have widespread closures.
“While existing data, mainly from Europe, indicates that it primarily affects the upper respiratory tract and typically resolves within four days, continued vigilance is crucial. The variant’s potential to infect more people and the risk of acquiring additional mutations that could pose clinical challenges underscore the importance of ongoing monitoring,” says Dr Mishra.
Many states are issuing advisories, urging people to avoid crowded spaces and wear masks, especially those with underlying health conditions or older individuals. This precautionary approach is aimed at minimising the impact of potential clinical challenges that may arise if the virus undergoes further mutations.
Fortunately, the virus’s clinical impact is relatively mild, often manifesting as a mild cold or even presenting no symptoms at all.
“While this is a positive aspect, the challenge lies in the virus’s unstoppable and swift transmission, prompting travel restrictions as a measure to curb its spread. However, such restrictions may have limited effectiveness,” says Dr Mishra.
The overarching advice remains consistent: To mitigate the spread, individuals should avoid crowded places, wear masks, and take protective measures. “These precautions are considered more effective than imposing travel bans, which may yield more harm than benefit,” adds Dr Mishra.
Dr Mishra, who was also the former director at the Center for Cellular Microbiology (CCMB), Hyderabad, said that the new variant doesn’t pose a specific threat or problem and appears to be milder compared to previous ones. However, the long-term effects of Covid-19, particularly in terms of “long Covid”, remain poorly understood.
“Studies in India and globally are limited, and the complex interplay of factors, such as genetic makeup, makes it challenging to draw definitive conclusions. Long Covid requires ongoing monitoring and correlation with Covid cases over time to ascertain patterns and causation accurately,” he adds.
Regarding vaccines, Dr Mishra says that studies suggest effectiveness against the JN.1 variant, with current vaccines offering substantial protection. While breakthrough infections may occur, disease severity remains minimal in vaccinated individuals.
Immunocompromised individuals may benefit from additional vaccine doses and new vaccines, such as Genova’s mRNA vaccine against the Omicron subvariant, have been approved which might be helpful against this variant as well.
“Clinical decisions about additional vaccine doses, especially for older individuals with comorbidities or compromised immune systems, should be made in consultation with healthcare professionals. Options like the fourth dose of an mRNA vaccine can be considered based on clinical recommendations, and the availability of approved options ensures flexibility in vaccination strategies,” he adds.
Dr Mishra says that their surveillance programme extends beyond Covid, encompassing other pathogens and antimicrobial-resistant (AMR) entities as our focal points.
“While our understanding and precise quantification of Covid trends are well-established, other pathogens and AMR cases are currently detected, and we are in the process of correlating them with city or hospital data to gain clarity,” says Dr Mishra.
He adds that although they are not immediately able to provide specific information about the prevalence of common cold, flu, or other AMR infections in the population, they are actively working towards achieving this through wastewater analysis.
“The goal is to develop a comprehensive surveillance system that not only identifies the presence of various viruses and AMR signatures but also quantifies their prevalence and correlates them with actual cases,” he says.
While this level of specificity may take some time to standardise, their ongoing efforts in detecting and analysing wastewater samples will contribute to achieving this objective.
The ultimate aim is to be able to report on scenarios involving infectious diseases, similar to what we currently do for Covid, with a focus on providing accurate and timely information.
“As we continue to refine our quantification methods, we anticipate being able to offer more detailed insights into the prevalence of different pathogens in the community,” he adds.
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