Vice President Harris’s flight to Vietnam was delayed because the embassy in Hanoi was suffering from “Havana Syndrome”.
Havana Syndrome is an unexplained illness. The US embassy in Havana first reported it as headaches, fatigue, hearing and vision loss, severe and debilitating cognitive impairment, tinnitus, brain fog, vertigo, and loss of motor control. The Secret Service is investigating to see if The White House is a super spreader, and particularly if Joe Biden is suffering from Havana Syndrome.
As you can see, Harris’s case is a bit more advanced.