Situation at a glance
On 2 October 2026, WHO became aware through media reports of the death of an employee of the Irkutsk Antiplague Research Institute (APRI) of Siberia and the Far East, the Russian Federation.
According to these reports, the individual died on 2 October following hospitalization for severe pneumonia on 29 September, and pneumonic plague was suspected as the cause of death, following occupational exposure in laboratory settings.
Following requests for verification from WHO, the National Focal Point for the International Health Regulations (2005) (NFP) of the Russian Federation confirmed the death and informed WHO that no case of plague had been registered recently in Irkutsk Oblast, that preventive and control measures had been implemented in accordance with national sanitary legislation, and that the laboratory testing of contacts detected no high-threat pathogens.
The authorities also reported that no biosecurity incidents had occurred in the laboratory, contrary to reports in the media, and that there were no further case of severe pneumonia linked to this case.
The NFP informed WHO that the case and all contacts had been tested for a range of microorganisms, including high-threat pathogens.
Test results were negative for the tested high-threat pathogens.
All contacts had been medically followed up in healthcare facilities or at home, and all remained asymptomatic throughout.
Quarantine measures were instituted in the hospital where the patient was being treated.
Based on the information provided by NFP, WHO has not identified evidence of ongoing transmission associated with this event.
A key uncertainty remains the absence of a confirmed diagnosis in the deceased laboratory worker.
WHO will continue to monitor the situation and assess any potential public health implications as further information becomes available.
Description of the situation
On 2 October 2026, WHO became aware through media reports of the death of an employee of the Irkutsk APRI of Siberia and the Far East, Russian Federation.
The individual died on 2 October following hospitalization for severe pneumonia on 29 September.
On 3 October, 5 October, 6 October and 7 October, WHO contacted the Russian Federation health authorities to verify the information reported by media including a purported second case and in accordance with Articles 9 and 10 of the International Health Regulations (2005) (IHR), WHO also asked for further information to assess the potential international public health implications in accordance with Article 6 of the IHR.
On 2 October, a public statement issued by the Irkutsk branch of Rospotrebnadzor (RPN), a federal agency that works to provide oversight and control of wellbeing and consumer rights and protection in the Russian Federation, indicated that a “special sanitary-epidemiological expert commission” had been convened for the suspected case of high-threat pathogen.
Sanitary and epidemic control measures were put in place, including identifying contacts who were placed under medical observation.
Russian Federation authorities stated at the time that all contacts were without symptoms and with negative laboratory results for high-threat pathogens.
On 6 October, WHO received a response to its verification request from the NFP of the Russian Federation, stating that no case of plague has been registered recently in Irkutsk Oblast, and confirming that an epidemiological investigation had been conducted following the identification of a case of severe pneumonia in an employee of the Irkutsk APRI.
According to authorities, the individual initially presented with symptoms compatible with an acute respiratory viral infection.
After testing negative for a number of high-threat pathogens, the patient was determined to have died from pneumonia of undetermined etiology.
Russian authorities informed WHO of the following:
§ that preventive and control measures had been implemented in accordance with national sanitary legislation;
§ that the widest possible range of contacts were identified, placed under medical observation and tested for high-threat pathogens, and
§ that as of 9 October, no high-threat pathogens within the laboratory’s research portfolio had been detected in any of the contacts, and
§ their medical observation has been discontinued.
The authorities further reported that no laboratory biosafety or biosecurity incidents had occurred at the institute, as determined by two independent investigations and stated that media reports suggesting otherwise were inaccurate.
According to the Russian Federation authorities, the situation continues to be monitored.
Following subsequent requests for information from WHO on 7 and 8 October, the NFP of the Russian Federation provided further information.
According to their official report, the patient and all identified contacts were tested for a broad range of pathogens, including influenza, SARS-CoV-2, other respiratory infections, and bacterial infections (including plague and streptococcus).
All results were reportedly negative for high-threat pathogens, and only two cases of COVID-19, three cases of rhinovirus, one case of Haemophilus spp., and other opportunistic infections were identified among contacts.
The authorities further reported that the fatality was not due to plague infection, had been vaccinated against the high-threat pathogens with which the employee had worked occupationally.
The report also stated that the individual had not travelled outside of Irkutsk Oblast during the two weeks prior to symptom onset.
WHO has offered support in the areas of high-threat pathogens and laboratory biosafety and biosecurity to the public health authorities in the Russian Federation.
In response to further information about the public health measures put in place, Russian Federation authorities reported that given the patient’s occupation, precautionary public health measures were implemented, and a broad range of contacts were identified and placed under medical observation either in healthcare facilities or at home.
Medical observation, including daily laboratory testing, was conducted for seven days and has been completed for all identified contacts.
All contacts remained asymptomatic and tested negative for the pathogens under investigation.
The Russian Federation authorities informed WHO that, apart from the hospital where the case was admitted, no other healthcare facility was placed under quarantine or subjected to additional public health measures, contrary to media reports.
Public health response
The NFP of the Russian Federation publicly announced that the regional sanitary and anti-epidemic commission convened an extraordinary meeting on 2 October.
RPN, the responsible agency, approved an operational action plan of sanitary and anti-epidemic measures, in accordance with national legislation, including contact tracing and medical follow-up, laboratory testing of identified contacts, enhanced epidemiological investigation and risk assessment and implementation of precautionary infection prevention and control measures.
Five Rospotrebnadzor organizations, including three research institutions, were involved in the measures.
The preventive and anti-epidemic measures were implemented in accordance with the patient's professional activities.
No infectious disease-related health concerns were identified.
More than 5500 laboratory tests were conducted, and none detected high-consequence or dangerous pathogenic microorganisms.
Testing was performed using a broad range of established laboratory methods, including bacteriological, biological, mass spectrometric, and molecular genetic techniques.
No high-threat pathogens were detected among contacts, and all follow-up activities were completed without identifying additional cases.
WHO risk assessment
WHO’s rapid risk assessment is a systematic and continuous process that characterizes the risk posed by a public health event and informs measures to reduce its impact and prevent international spread.
A key uncertainty for this event is the absence of a confirmed diagnosis in the deceased laboratory worker.
According to information provided by the national authorities, testing did not identify plague or other tested high-threat pathogens, and the death has been classified as pneumonia of undetermined etiology.
However, WHO has not received information identifying the causative agent responsible for the fatal illness.
Given the absence of a confirmed diagnosis, WHO is not in a position to independently assess whether the duration of the reported monitoring period for contacts was sufficient to exclude all plausible causes of the fatal illness.
The occupational setting of the case remains an important consideration.
The deceased individual worked at an institution that handles high-consequence pathogens, and precautionary public health measures were reportedly implemented because of the individual's professional activities.
While the information provided by the authorities does not indicate infection with tested high-threat pathogens or identify additional linked cases, the source of the fatal illness remains undetermined.
A laboratory-associated exposure therefore cannot be fully excluded at this stage.
Based on the information provided by NFP, WHO has not identified evidence of ongoing transmission associated with this event.
However, confidence in the assessment remains limited by the absence of a confirmed etiological diagnosis, and the remaining uncertainty regarding the source and mode of exposure.
Additional clinical, epidemiological and laboratory information, including confirmation of the diagnosis in the deceased laboratory worker, is required to improve confidence in the assessment.
WHO will continue monitoring the situation and assess any potential public health implications as further information becomes available.
WHO advice
WHO encourages all States Parties to the IHR to actively engage with the WHO IHR Contact Points in their respective WHO Regional Office for timely event-related communications, including by applying, to that effect, the decision instrument contained in Annex 2 of the IHR, intended to inform the decision by national authorities to notify WHO (Article 6) or to consult with WHO (Article 8).
As the etiology of the fatal illness remains undetermined, further investigation of available clinical specimens and epidemiological information should continue, as appropriate.
Additional laboratory testing, including confirmatory testing by reference laboratories where needed, may assist in establishing the causative agent and refining the public health risk assessment.
Depending on seasonality and local epidemiology, States Parties may consider enhancing or strengthening community-based, event-based or sentinel surveillance for respiratory infections and strengthening testing capacities for respiratory pathogens.
Public health authorities may also encourage uptake of recommended vaccinations against seasonal influenza, COVID-19, pneumococcal diseases and other vaccine-preventable respiratory infections as appropriate.
Given that the reported event involved a laboratory worker and that initial media reports suggested a possible occupational exposure or laboratory-related incident, WHO recalls the importance of maintaining robust biosafety, biosecurity, and infection prevention and control practices in laboratories handling potentially hazardous biological agents. This recommendation is precautionary in nature and does not imply that a laboratory-associated infection or incident has been confirmed in this event.
Should an occupational exposure to biological hazards occur among personnel working in laboratory settings, regardless of the specific role or the nature of the clinical outcome, WHO recommends strict adherence to appropriate biosafety, biosecurity and infection prevention and control measures in accordance with established protocols.
These measures are intended to minimize the risk of occupational exposure to and unintended release of infectious agents and should be applied consistently as part of routine laboratory practice, without implying that a particular infection or clinical condition was necessarily acquired as a result of occupational exposure in the laboratory setting.
Based on the information currently available, WHO does not advise any restrictions on travel or trade related to this event.
WHO will continue monitoring the situation and updating its recommendations as additional information becomes available.
Further information
° Rospotrebnadzor: a full range of preventive measures has been completed in Irkutsk. Available here: https://www.rospotrebnadzor.ru/deyatelnost/epidemiological-surveillance/?ELEMENT_ID=33189
° Shelekhovsky District official website, Extraordinary meeting of the Regional Sanitary and Anti-Epidemic Commission. Available here: https://www.sheladm.ru/p/044cd85d94814bb99845ef58826e6adc
° Irkutsk region Governor. Available here: https://web.max.ru/-68185301813993
° Irkutsk Anti-Plague Research Institute of Siberia and Far East. Available here: https://irknipchi.ru/index_eng.htm
° World Health Organization (2020). Laboratory biosafety manual, 4th ed. World Health Organization. Available here: https://iris.who.int/handle/10665/337956.
° World Health Organization (2021). WHO guidelines for plague management: revised recommendations for the use of rapid diagnostic tests, fluoroquinolones for case management and personal protective equipment for prevention of post-mortem transmission. Available here: https://iris.who.int/handle/10665/341505.
° World Health Organization. Fact Sheet Plague. Available here: https://www.who.int/news-room/fact-sheets/detail/plague
Citable reference: World Health Organization (10 October 2026). Disease Outbreak News; Pneumonia of undetermined etiology in the Russian Federation. Available at: https://www/who.int/emergencies/disease-outbreak.news.item/2026-DON620
Source:
Link: https://www/who.int/emergencies/disease-outbreak.news.item/2026-DON620
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