Key facts
- Russian health authorities have reported no recent plague case in Irkutsk Oblast and report a case of pneumonia of unknown aetiology in a laboratory employee.
- Russian health authorities reported that preventive measures, including epidemiological investigations, medical observation and testing of contacts have been implemented according to national legislation and are now completed; and no high-threat pathogen was detected in any of the identified contacts.
- Following WHO's request for further information, Russian health authorities reported that no laboratory biosafety or biosecurity incident had occurred in the laboratory where the case was employed and determined that the cause of death of the case was pneumonia of unknown aetiology.
- ECDC is actively monitoring this event and is in close contact with WHO EURO and other international stakeholders, including global CDCs, to obtain additional information as it becomes available.
- The available information on this event is not sufficient to draw a firm conclusion regarding the potential risk to the EU population. The assessment will be reviewed should additional information become available.
Overview
Update:
According to WHO’s Disease Outbreak News (DON) on pneumonia of undetermined aetiology in Russian Federation from 10 October 2026 and referring to information shared with WHO by the IHR NFP of the Russian Federation, the case presented with respiratory symptoms and was initially diagnosed with acute respiratory viral infection (ARVI) before she passed away.
Due to her employment at the Irkutsk Antiplague Research Institute (APRI), comprehensive control measures were immediately implemented upon receipt of the information of this case, in accordance with national sanitary legislation. Contacts were identified, placed under medical observation and tested for high threat pathogens.
As of 9 October, medical monitoring has been completed for all identified contacts, all of whom with no reported symptoms. More than 5 000 laboratory tests were performed in identified contacts. According to Russian authorities, the researcher and all identified contacts were tested for several pathogens, including influenza, SARS-CoV-2, plague, and streptococcus, also stating that no dangerous pathogenic microorganisms were identified. Russian authorities report that the researcher was vaccinated and possessed immunity to the hazardous infectious agents with which she worked. It is also reported that the researcher did not travel outside of Irkutsk in the two weeks prior to clinical presentation. Given that no pathogen was identified in the tests performed, Russian health authorities determined that the cause of death of the case was pneumonia of unknown aetiology.
Inspections were carried out at APRI by two commissions responsible for monitoring compliance with biological safety requirements, which reported that appropriate controls were maintained in work involving pathogenic microorganisms and did not identify any incidents or accidents involving pathogenic microorganisms. Preventive and anti-epidemic measures have been implemented and there are no epidemiological risks to the population of the city of Irkutsk or Irkutsk Oblast.
Background: On 2 October 2026, according to multiple media reports pending verification, authorities in Irkutsk Oblast, Russia, initiated emergency anti-epidemic measures following the death of a 28-year-old laboratory technician, employed at the Irkutsk Research Anti-Plague Institute of Siberia and the Far East. Russian authorities have officially classified the case as "pneumonia of unknown aetiology".
According to media reports, the patient allegedly experienced a laboratory incident on 25 September 2026, when she reportedly broke a tube containing Yersinia pestis while working with live biological material. These reports have not been confirmed. Russian health authorities have reported no recent plague case in Irkutsk Oblast. Following the alleged incident, she reportedly became unwell within several days and was admitted to Shelekhov District Hospital on 29 September 2026 with severe pneumonia. Initial clinical suspicion reportedly included severe COVID-19; however, her condition deteriorated rapidly, requiring intensive care and mechanical ventilation. She died during the night of 1-2 October 2026 in the intensive care unit of Shelekhov District Hospital.
On 2 October 2026, the Governor announced that a suspected case of a "particularly dangerous infection" was under investigation and confirmed that a full package of anti-epidemic measures had been initiated. An extraordinary meeting of the regional sanitary and anti-epidemic commission was convened with participation of Head of Rospotrebnadzor (the Federal Service for the Oversight of Consumer Protection and Welfare in Russia) and Chief State Sanitary Physician of the Russian Federation. An operational response plan was approved and contact tracing was initiated.
Public health measures included quarantine restrictions at Shelekhov District Hospital, suspension of admissions and discharges in affected departments, enhanced epidemiological investigations and medical monitoring of contacts. Russian media reported that approximately 189-200 contacts were placed under observation, including institute staff, healthcare workers, ambulance personnel and hospital patients. Identified contacts have been isolated in medical institutions, of which 114 patients are in one hospital, 63 in another, and another 12 people are kept in the anti-plague institute. The Governor stated that all identified contacts were under medical supervision and had negative laboratory test results at the time of reporting.
Additional precautionary measures reported by Russian and independent media included cancellation of public events in Irkutsk, mandatory mask use at some workplaces, quarantine of several healthcare facilities, including the Shelekhov hospital, were the deceased person was hospitalised, and isolation of contacts in designated hospitals.
On 4-5 October 2026, according to media reports, Rospotrebnadzor, reported that expanded laboratory investigations did not identify microorganisms associated with the deceased patient's professional activities. The agency stated that no laboratory accidents involving pathogenic microorganisms had been documented at the institute, no infectious disease clusters had been identified among staff, and the patient had been diagnosed with "pneumonia of unknown aetiology". Rospotrebnadzor further described the sanitary-epidemiological situation in Irkutsk and Shelekhov as stable.
On 6 October 2026, the World Health Organization's Director General reported that, in response to WHO's verification request, Russian health authorities reported no recent plague case in Irkutsk Oblast. They reported that preventive measures, including epidemiological investigations and medical observation and testing of contacts have been completed. Moreover, Russian health authorities reported no high-threat pathogen detected in any of the identified contacts.
For information, no autochthonous plague cases have been reported in the EU/EEA in the last decades. Please consult the ECDC factsheet for further information on this disease.
Sources: media source 1, media source 2, media source 3, media source 4, WHO's Director General post, WHO DON
ECDC assessment
The available information of this event (absence of a confirmed diagnosis, no identification of the causative agent, uncertainty regarding the source and mode of exposure) is not sufficient to draw a firm conclusion regarding the potential risk to the EU population. The assessment will be reviewed should additional information become available.