A 28-year-old laboratory technician at an anti-plague research institute in Siberia has died from a severe pneumonia-like illness, prompting Russia to place nearly 200 people under medical observation.

Darya Shipilova worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East. She was hospitalized on September 29 and died on October 2.

Russia's health watchdog Rospotrebnadzor classified her diagnosis as "pneumonia of unknown etiology" and said no microorganisms linked to her work were found in her samples.

Local media reports said she fell ill after breaking a test tube, and regional officials indicated suspected pneumonic plague, though this is unconfirmed.

Governor Igor Kobzev said contacts tested so far remain asymptomatic and negative. About 189 people are in isolation across hospitals, reports said.

The White House is monitoring the case, and the WHO has asked Russia for more information on the cause of death.