The findings of the study posted on the ‘MedRxiv’ preprint server revealed that the number of infected people has been much higher than the reported cases. The team of researchers claimed that they detected COVID-19 variants in sewage water, months before the virus showed up in the clinical tests. The study conducted in Bengaluru revealed that the Omicron sub-variant BA.2.10.1 and BA.2.12 were detected in wastewater in January. 

In the study, the researchers analyzed 878 wastewater samples from January 1 to June 30. The analysis data showed that BA.2.10 was the most dominant lineage (14.83%), followed by BA.2 (10.49%), BA.1.1529 (5.1%), BA.2.12 (5%), and BA. 2.10.1(3.1%). They also detected the mutation of two recombinant lineages of BA.1.1 and BA.2-XM.

The study showed that the seven dominant lineages changed over time as percentages of BA.2, XM, and XQ started increasing whereas the percentages of BA.2.10, BA.2.10.1 decreased between Januarys to June. They also found that the BA.2 variants remained dominant in May, while its sub-lineage BA.2.12 was the most dominant infectious agent with a high viral load during the third wave in India.

(Source: https://health.economictimes.indiatimes.com/news/industry/covid-variants-found-in-sewage-even-before-surge-in-cases-study/93039909 )