The World Health Organisation (WHO) said it still does not know what caused the pneumonia that killed a Russian laboratory worker at an anti‑plague research centre in Siberia on October 2.
The UN health agency confirmed that no case of plague has been registered. Russian authorities reported that the worker and about 200 contacts were tested for high‑threat pathogens and all results were negative. None of the contacts showed symptoms, and no further linked cases of severe pneumonia have been identified.
In its first full Disease Outbreak News update since the case emerged, the WHO called for continued investigation and noted that the absence of a confirmed diagnosis in the deceased worker remains a key uncertainty. The agency urged additional clinical, epidemiological and laboratory information to improve confidence in the assessment.
Initial, unconfirmed reports suggested the death might have been linked to pneumonic plague, a severe form of pneumonia that can spread between people. Russian officials said the worker had been appropriately vaccinated and that no microorganisms linked to her work were found in her body. They also completed health checks on all contacts and provided full information to the WHO, following established procedures.
