Hundreds of people have been hospitalized with a mysterious illness in southern India—and COVID-19 has been ruled out as the cause. According to BBC News, at least one person has died and more than 300 have been landed in hospitals by the sickness in the southern state of Andhra Pradesh. “The people who fell sick, especially the children, suddenly started vomiting after complaining of burning eyes. Some of them fainted or suffered bouts of seizures,” one medical official was quoted as saying. Patients’ blood samples didn’t show any sign of viral infection, victims have tested negative for COVID-19, and water contamination or air pollution have been ruled out by medical investigators. The hospitalizations couldn’t come at a worse time—India has world’s second-highest coronavirus caseload.