reported a possible case. tonight here, more on what this havana syndrome is, and here s abc s receive knstephanie ramos. reporter: tonight, vice president kamala harris has landed in vietnam after her flight was delayed over a, quote, possible anomalous health incident in hanoi.madamd you continue your trip? reporter: the reported incident affected a staffer at the u.s. mission in vietnam in recent days. allegedly an incident of havana syndrome the mysterious onset of symptoms like headache, earache, nausea and trouble seeing or balancing. cases were first reported by american personnel in havana, cuba, in 2016 and 2017. many of them diagnosed with traumatic brain injuries. since then, dozens of u.s. officials in multiple countries have reported symptoms. can you share more about the possible incident of havana syndrome that delayed the vice president s trip? while this is not a confirmed case at this point in time, we take any reported incident which was recent and was