Covid-19 (covid-19) continues to spread and mutate all over the world. Early detection of new mutated strains is conducive to timely public health interventions. U.S. researchers have newly discovered a method that can detect the covid-19 variant strain from wastewater in advance, which can give early warning of the epidemic of the new variant strain. With the discharge of people's daily life, the RNA (ribonucleic acid) of covid-19 will accumulate in the wastewater. At present, researchers in many countries around the world have developed methods to detect novel coronavirus in wastewater, but these methods mainly detect the virus content in current wastewater for estimating the community transmission of the virus. Scientists hope to further determine which mutant strains are spreading and the prevalence of transmission, but they have been plagued by low-quality data. Researchers from the University of California, San Diego and other institutions recently used nanotechnology to increase the amount of novel coronavirus RNA used for sequencing in wastewater samples, and developed a tool called "freyja" to identify mutant strains in wastewater samples. The research paper has been published in the British journal Nature recently. Researchers collected wastewater samples from local universities and surrounding communities to verify the accuracy of the method. They found that using new tools to detect wastewater samples can detect alpha and delta variant strains two weeks ahead of human testing methods such as clinical (nasopharyngeal) swabs. They also tested positive for the first infected person of Omicron strain in San Diego. About 10 days ago, they detected the strain in wastewater and traced the subtype Ba of Omicron strain 1. The spread among people surged. However, it is not clear whether this technology can be used to track the rapidly spreading Omicron virus subtype ba 4 and ba 5. Because they are difficult to distinguish. The researchers said that this new technology can be used to track the emerging covid-19 variant, early detect and identify the hidden transmission of the new variant, and accelerate the public health response. (Xinhua News Agency)