Researchers investigating mysterious COVID-19 mutations found signs of the virus in the city’s massive rat population — sparking concerns the disease could jump from the vermin to humans.

A new study by scientists at the University of Missouri and the USDA identified the virus in New York City rats and also found that some species of the notoriously disease-riddled animals are susceptible to the Alpha, Delta, and Omicron variants of COVID-19.

Along with the virus mutations, scientists also found rat DNA in the samples they were studying, which prompted Lenoch and her colleagues to look at the city’s rodent population as a possible source.

While the origins of the cryptic COVID-19 mutations in New York City’s sewers remain a mystery, scientists studying the coronavirus in wastewater have made recent advancements in their ability to trace such variations.