The so-called 'Havana syndrome' was initially reported between 2016-2017 by US diplomats from embassies in Cuba and China, who complained about a number of mysterious symptoms, including dizziness, headache, nausea, vision and cognitive problems. Officials haven't yet determined the cause of the distress.

The US Department of State has initiated a probe into cases of 'Havana syndrome' recently reported by employees of the American embassy in Vienna, Austria, The Hill reported on Saturday.

“In coordination with our partners across the US government, we are vigorously investigating reports of possible unexplained health incidents among the US Embassy Vienna community,” the State Department said in a statement obtained by The Hill.

Earlier in the day, the New Yorker magazine first reported on health disorders experienced by some 20 diplomats and other officials in Vienna since US President Joe Biden took the office.

The first cases of the mysterious syndrome were reported in 2016 by members of the US diplomatic mission in Cuba. Later, similar incidents occurred among American diplomats in China. The victims reported various symptoms related, in part, to concussion – hearing loss, nausea, headaches and imbalance. Reports claim that the diplomats were not physically affected.