A staff member of Russia's Irkutsk Anti-Plague Institute of Siberia and the Far East has been diagnosed with pneumonia of unknown cause, while the epidemiological situation in Irkutsk Region and the cities concerned remains stable, the Russian Federal Service for the Oversight of Consumer Protection and Welfare said on Tuesday.

According to the agency, no microorganisms related to the patient's professional activities were detected in samples taken from her. The institute also confirmed that no accidents had occurred while the facility was carrying out work involving pathogenic microorganisms. An expert panel sent by the agency to the institute confirmed the findings.

Following the case, local authorities immediately implemented comprehensive epidemic prevention measures. No infectious disease cases have been reported among staff at the institute over the past 10 days.

WHO Director-General Tedros Adhanom Ghebreyesus said in a post on X that the patient was hospitalized with severe pneumonia and died on October 2. He said the WHO had been actively following the case since reports of the death first emerged. Russian health authorities informed the WHO that no plague cases had been reported recently in Irkutsk Region, and no high-threat pathogens had been detected among the patient's contacts.