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India is witnessing a steady rise in COVID-19 cases since May 2025. Just in the last fortnight, the country's active caseload has grown 18 times, going from 257 on May 19 to 4,866 on June 5. Although the infections are mild, 51 people have died of the infection in the country since the beginning of 2025; most of them had comorbidities, other ailments, cancer or were elderly.
It is unclear if the situation will snowball into a COVID-19 wave but clues from wastewater indicate a concern. The Council of Scientific & Industrial Research-National Chemical Laboratory (NCL) found the presence of the virus in wastewater samples from every sewage treatment plant in Pune, according to a news report in The Times of India.
It started with just one STP showing traces of SARS-CoV-2 on April 22, said NCL scientist Mahesh S Dharne to the newspaper. By May 6, samples from all the 10 STPs in the city tested positive for coronavirus through RT-PCR examination. This is indicative of the viral load in the entire community.
It is a matter of concern because wastewater surveillance has been considered an early warning for case spikes. Even in this instance, the scientist noted that the "viral load pattern" was similar to those observed before the infection surge picked up pace in the past.
Since the initial days of the pandemic, this method has been used to understand the viral load in a particular population. A person with coronavirus infection can shed viral material in faecal sampled up to 35 days. It is said that the virus can be excreted by symptomatic, asymptomatic and presymptomatic individuals, wrote Rajeshwari Sinha, Programme Manager, Food Safety and Toxins, Centre for Science and Environment, New Delhi in a Down To Earth story.
In the first half of 2020, sewage samples were tested in Hyderabad and the analysis showed that some 6 per cent of the city's population had the infection. The findings published in August 2020 showed that some 600,000 people in the city were 'potentially infected'. Most of them were asymptomatic, which is why the clinically identified cases and hospitalisations were much lower.
A study that analysed over 1,100 wastewater samples from the city during May 2022 and May 2023 had found that the population has a high case load although not as many cases were being report. This means the virus was being passed on undiagnosed, the researchers wrote, in something they termed a 'silent wave'. The findings were published in December 2024.
Moreover, the examination of wastewater also revealed virus lineages in circulation months ahead of their clinical identification, the authors added. "The BA.2.86.X was identified 103 days prior to its clinical detection in Pune, highlighting WBE's remarkable lead time."
Globally, SARS-CoV-2 infections have been on the rise since mid-February 2025, according to a situation report by the World Health Organization posted on May 28, 2025. The test positivity rate reached 11 per cent, highest since July 2024, the United Nations health organisation wrote. "This rise is primarily observed in countries in the Eastern Mediterranean, South-East Asia, and Western Pacific regions."
According to WHO data till May 18, 2025, the number of cases in the South-East Asia region was a lot higher than any other part of the world. In the seven days till May 18, the region had recorded 58,720 cases, while Europe had some 2,800 cases and the Americas 2,300.