The death of a young laboratory worker in Siberia has triggered a major health response in Russia, with reports of a possible plague exposure that officials have not confirmed. Daria Shipilova, 28, worked at the Irkutsk Anti-Plague Institute of Siberia and the Far East.

According to the regional outlet People of Baikal, Shipilova broke a test tube containing the pathogen behind pneumonic plague on September 25. She was admitted to a hospital in Shelekhov on September 29 with severe pneumonia and died during the night of October 1-2.

Authorities placed nearly 200 of her contacts under medical observation and quarantined parts of the hospital. Public gatherings in the Irkutsk region were cancelled, and a criminal case was opened into possible safety violations. Russia’s chief sanitary physician Anna Popova flew to Irkutsk.

On October 4, health watchdog Rospotrebnadzor said the cause was pneumonia of unknown origin, with no evidence of a laboratory accident. The two accounts have not been reconciled, and contacts have so far tested negative.