Many countries have tightened their travel restrictions after a new coronavirus variant emerged in South Africa earlier this week.
The UK, Singapore and Japan are among those rushing to stricter quarantine measures.
Other countries have banned flights from South Africa and neighbouring countries.
Scientists still have much to learn about the variant, but say they are very worried about it.
A top health official calls it “the most significant variant” to date, but the UK didn’t confirm any cases to date.
“It is bad news, but it’s not doomsday,” an Oxford scientist tells the BBC.
Transport Secretary Grant Shapps says the UK is taking a “safety-first approach” in regard to the travel ban.
Countries including Germany, Italy, Israel and Singapore have also restricted travel.
The UK has recently imposed travel restrictions on six African countries over the new coronavirus variant.
The World Health Organization will hold a special meeting later today to discuss the variant.
The Delta variant became the dominant variant in most of the world over the summer.
The Delta variant is far more infectious than the previously dominant Alpha variant.
The variant is more transmissible than others and was first identified in India. But it has spread rapidly in the UK.
However, Portugal was the first European Union nation to announce that the Delta variant was now dominant on its territory.
According to the WHO, it is “well on its way” to accounting for a majority of worldwide cases of Covid-19.