Infectious disease

WHO says cause of Russian lab worker’s death remains unknown

WHO says more clinical, epidemiological and laboratory information is needed to confirm the lab worker’s diagnosis.

Reported by 2 outlets Monday, October 12, 2026

A gloved hand using a pipette in a laboratory
Photo: Public domain

The World Health Organization said it still does not know what caused a worker’s death at a Russian laboratory that studies plague and other illnesses. The Guardian reported that the worker was 28 and died after developing severe pneumonia. WHO cited initial, unconfirmed reports suggesting pneumonic plague.

Russian health officials had conducted more than 5,500 tests and found no evidence of dangerous pathogenic microorganisms, WHO said. The agency said further clinical, epidemiological and laboratory information, including confirmation of the worker’s diagnosis, is needed to improve confidence in its assessment. WHO called for the investigation to continue and referred to a purported second case. Russia has denied there was a second case.

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