How 2 Flights to Europe May Have Spurred Spread of New Variant

A confounding array of Covid rules and lax enforcement of mask wearing may have sent on infected passengers on two KLM flights from South Africa to “who knows where.”

For the hundreds of passengers traveling from South Africa to Amsterdam on Friday, flight KL592 had all the trappings of international travel in the Covid era.

They came armed with paperwork proving their eligibility to fly, and check-in agents sifted through a bewildering assortment of requirements determined by final destination. Some countries, like the United States, required vaccinated travelers to show negative test results. Others didn’t. On the long flight, only some wore masks, passengers said, as flight attendants often let the slipping masks slide.

But while the flight was en route, and the passengers slept or watched their screens, everything changed on the ground.