North American spies and diplomats stationed in Cuba between 2016 and 2018 reported a range of unexplained illnesses: headaches, dizziness, nausea, fatigue.
Some believed the symptoms were caused by sonic weaponry being used against the American agents by hostile parties.
But new studies by the National Institutes of Health in the United States of America have failed to find any evidence of brain injuries.
Dr Robert Bartholomew is the co-author of the 2020 book Havana Syndrome and speaks to Emile Donovan.
Robert Bartholomew, co-author of 'Havana Syndrome: Mass Psychogenic illness and the Real Story Behind the Embassy Mystery and Hysteria'. Photo: Auckland University