The World Health Organization announced on Saturday, October 18, that it is still unknown what caused a Russian worker to contract pneumonia and die this month at a research center for the fight against plague in Siberia.

This organization emphasized in publishing statements that no case of plague was recorded.

The World Health Organization said the Russian government surveillance agency reported that tests performed on this Irkutsk region lab worker and his contacts were negative for high-risk pathogens.

According to this organization, people in contact with him still have no symptoms and no other case of severe pneumonia related to this incident has been identified.

This laboratory worker fell ill and died on the 10th in a hurry, in a condition whose details have not been published. The incident caused authorities to quarantine about 200 people and raised public health concerns on social media.