Since the first media reports, @WHO has been actively following up on the reported death of a laboratory worker at the Irkutsk Antiplague Research Institute in Irkutsk oblast, Russian Federation. The individual died on 2 October 2026 after being hospitalised with severe pneumonia. Initial media reports suggested pneumonic plague following an alleged accidental laboratory exposure. In response to WHO’s verification request under the International Health Regulations, the Russian health authorities reported that no case of plague had recently been registered in Irkutsk oblast. They informed WHO that an epidemiological investigation had been conducted, preventive and control measures implemented, and identified contacts placed under medical observation and tested. They reported that no high-threat pathogens had been detected among the contacts and that medical observation of all identified contacts had been completed. WHO has remained in contact with the Russian health authorities and has offered technical support. WHO has requested further information to clarify the cause of the severe pneumonia, the pathogen that prompted the public health measures, and media reports of a second employee with pneumonia of undetermined cause. Timely, complete and transparent information sharing under the International Health Regulations is essential to clarify conflicting reports and enable an accurate assessment of potential public health risks.