The World Health Organization (WHO) has sought additional information from Russia regarding the death of a laboratory worker at the Irkutsk Anti-Plague Research Institute in Siberia, following concerns over a possible link to pneumonic plague. The cause of the worker’s death remains publicly unconfirmed, and Russian authorities have denied that a plague case was detected.

WHO Director-General Dr Tedros Adhanom Ghebreyesus said the organisation requires further information about the cause of the severe pneumonia, laboratory test results, the public health measures implemented and reports of a second employee with pneumonia of undetermined origin. WHO has emphasised that timely and transparent information-sharing is essential to assess potential public health risks accurately.

The 28-year-old worker, identified by media reports as Darya Shipilova, died on October 2, 2026, after being hospitalised with severe pneumonia. Initial reports raised concerns about pneumonic plague because she worked at a research institute that studies dangerous pathogens, including Yersinia pestis, the bacterium responsible for plague. However, no confirmed diagnosis of plague has been publicly established

Russian health authorities said approximately 200 people were initially placed under quarantine or medical observation following the incident. According to Russia’s public health watchdog, extensive testing found no plague cases among the deceased worker’s contacts and no evidence that her illness was caused by pathogens associated with her work. Reports also indicated that testing identified cases of COVID-19 and rhinovirus among contacts.

The WHO has continued seeking clarification under the International Health Regulations (IHR), which provide a framework for countries to notify and share information about public health events that may have international implications. The organisation has said its assessment will be updated as further information becomes available.

The incident has drawn international attention because pneumonic plague can spread through respiratory droplets and can become life-threatening without prompt treatment. However, the current case does not establish a confirmed plague outbreak, and the available information does not indicate sustained person-to-person transmission.

The WHO’s request highlights the importance of transparent reporting, laboratory verification and coordinated international surveillance when unexplained illnesses occur in facilities handling high-risk pathogens.