US Secretary of State Marco Rubio said the country is closely monitoring the case of the technician who died at a plague research centre in Siberia, with a risk of pneumonic plague, but no cause for alarm, according to the BBC.

Irkutsk’s governor announced the cause of death as “pneumonia of undetermined etiology” and said no microorganisms linked to her work had been found in her biological samples. Rospotrebnadzor inspected the Anti-Plague Institute of Siberia and the Far East and found no emergency situation there.