Russia has not confirmed a cause of death for the 28-year-old woman lab worker, who died on 2 October, and the WHO says this leaves it unable to assess the risk of the event.
On 6 October Russia's National Focal Point told the WHO that no plague case was recorded in Irkutsk Oblast and that the worker died of pneumonia of undetermined etiology.
The WHO has seen no evidence of ongoing transmission, but says its confidence remains limited by the absence of a confirmed etiological diagnosis.
Wprost reports that around 200 people were placed under quarantine and observation, and Russian authorities say all tested contacts were negative for high-threat pathogens.

The World Health Organization released a disease outbreak report over the weekend of 10 and 11 October on the death of a 28-year-old woman lab worker at the Irkutsk Antiplague Research Institute in Siberia. The agency said Russia has yet to report a confirmed cause of death, which it called a key uncertainty that makes it impossible to assess the risk of the event or whether Russia's public health measures were adequate. According to Wprost, she was admitted to hospital on 29 September with symptoms of severe pneumonia and died on 2 October. The WHO has seen no evidence of ongoing transmission, but it wrote in its report:
“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.”
Wprost reports that WHO director-general Tedros Adhanom Ghebreyesus said the risk assessment is hampered because Russia has not provided complete information about the event.
On 2 October the Irkutsk branch of Rospotrebnadzor said a special sanitary-epidemiological expert commission had met over a suspected case of a high-threat pathogen, and that all contacts had tested negative for high-threat pathogens. Wprost reports that about 200 people were placed under quarantine and observation. On 6 October Russia's National Focal Point for the International Health Regulations told the WHO that no case of plague had been recorded in Irkutsk Oblast and that the worker died of pneumonia of undetermined etiology after tests for several high-threat pathogens came back negative. Russian officials also said no biological safety procedures were breached at her workplace, according to Wprost. Early local media reports had suggested she died of plague after a lab accident, possibly a broken test tube, a claim the official findings do not support.
The WHO says it learned of the death from media reports on 2 October and then requested information from Russian authorities on 3, 6, 7 and 8 October. The first Russian response came on 6 October, four days after the requests began. The sequence is set out below.
Donald Trump had said he would raise the plague with Vladimir Putin, but after their call on Friday, 9 October, he announced an agreement on Russian diesel imports to the United States instead. In a Guardian column, Devi Sridhar argued that the lack of transparency from Russian authorities makes the case unusual, given long-running concern about biological weapons research. Initial local media coverage described the institute as rumoured to be involved in such research, a claim no official source has confirmed. Ashish Jha, the former US White House Covid-19 response coordinator, wrote on social media that US intelligence assesses Russia's scientists continue developing biological weapons capabilities.
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The WHO says Russia has not confirmed a cause of death for a 28-year-old woman lab worker in Irkutsk and has seen no evidence of ongoing transmission. Russian authorities say no plague case was recorded in the region and point to pneumonia of undetermined cause.
AI text based on reports by Le Parisien, Ars Technica, The Telegraph and other publishers. Published .